RFC 1013 - X Window System Protocol, version 11: Alpha update April 1987
(Formats: TXT)


Network Working Group                                Robert W. Scheifler
Request for Comments: 1013                                     June 1987
X WINDOW SYSTEM PROTOCOL, VERSION 11 Alpha Update April 1987 Copyright (c) 1986, 1987 Massachusetts Institute of Technology X Window System is a trademark of M.I.T. Status of this Memo This RFC is distributed to the Internet community for information only. It does not establish an Internet standard. The X window system has been widely reviewed and tested. The internet community is encouraged to experiment with it. Distribution of this memo is unlimited (see copyright notice on page 2). M.I.T. [Page 1] RFC 1013 June 1987 Permission to use, copy, modify, and distribute this document for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice are retained, and that the name of M.I.T. not be used in advertising or publicity pertaining to this document without specific, written prior permission. M.I.T. makes no representations about the suitability of this document or the protocol defined in this document for any purpose. It is provided "as is" without express or implied warranty. Author: Robert W. Scheifler Laboratory for Computer Science 545 Technology Square, Room 418 Cambridge, MA 02139 Contributors: Dave Carver (Digital HPW) Branko Gerovac (Digital HPW) Jim Gettys (MIT/Project Athena, Digital) Phil Karlton (Digital WSL) Scott McGregor (Digital SSG) Ram Rao (Digital UEG) David Rosenthal (Sun) Dave Winchell (Digital UEG) Implementors of initial server who provided useful input: Susan Angebranndt (Digital) Raymond Drewry (Digital) Todd Newman (Digital) Invited reviewers who provided useful input: Andrew Cherenson (Berkeley) Burns Fisher (Digital) Dan Garfinkel (HP) Leo Hourvitz (Next) Brock Krizan (HP) David Laidlaw (Stellar) Dave Mellinger (Interleaf) Ron Newman (MIT) John Ousterhout (Berkeley) Andrew Palay (ITC CMU) Ralph Swick (MIT) Craig Taylor (Sun) Jeffery Vroom (Stellar) This document does not attempt to provide the rationale or pragmatics required to fully understand the protocol or to place it in perspective within a complete system. Knowledge of X Version 10 will certainly aid in understanding this document. M.I.T. [Page 2] RFC 1013 June 1987 The protocol contains many management mechanisms that are not intended for normal applications. Not all mechanisms are needed to build a particular user interface. It is important to keep in mind that the protocol is intended to provide mechanism, not policy. This document does not attempt to define precise formats or bit encodings. ------------------------------------------------------------------- M.I.T. [Page 3] RFC 1013 June 1987 SECTION 1. TERMINOLOGY Access control list X maintains a list of hosts from which client programs may be run. By default, only programs on the local host may use the display, plus any hosts specified in an initial list read by the server. This "access control list" can be changed by clients on the local host. Some server implementations may also implement other authorization mechanisms. Active grab A grab is "active" when the pointer or keyboard is actually owned by the single grabbing client. Ancestors If W is an inferior of A, then A is an "ancestor" of W. Atom An "atom" is a unique id corresponding to a string name. Atoms are used to identify properties, types, and selections. Backing store When a server maintains the contents of a window, the off-screen saved pixels are known as a "backing store". Bit gravity When a window is resized, the contents of the window are not necessarily discarded. It is possible to request the server (though no guarantees are made) to relocate the previous contents to some region of the window. This attraction of window contents for some location of a window is known as "bit gravity". Bitmap A "bitmap" is a pixmap of depth one. Button grabbing Buttons on the pointer may be passively "grabbed" by a client. When the button is pressed, the pointer is then actively grabbed by the client. Byte order For image (pixmap/bitmap) data, byte order is defined by the server, and clients with different native byte ordering must swap bytes as necessary. For all other parts of the protocol, the byte order is defined by the client, and the server swaps bytes as necessary. Children The "children" of a window are its first-level subwindows. M.I.T. [Page 4] RFC 1013 June 1987 Client An application program connects to the window system server by some interprocess communication (IPC) path, such as a TCP connection or a shared memory buffer. This program is the window system server. More precisely, the client is the IPC path itself; a program with multiple paths open to the server is viewed as multiple clients by the protocol. Resource lifetimes are controlled by connection lifetimes, not by program lifetimes. Clipping regions In a graphics context, a bitmap or list of rectangles can be specified to restrict output to a particular region of the window. The image defined by the bitmap or rectangles is called a "clipping region". Color cell An entry in a colormap is known as a "color cell". An entry contains three values specifying red, green and blue intensities. These values are always viewed as 16 bit unsigned numbers, with zero being minimum intensity. The values are scaled by the server to match the display hardware. The components of a cell are coincident with components of other cells in DirectColor and TrueColor colormaps. Colormap A "colormap" consists of a set of color cells. A pixel value indexes the color map to produce intensities to be displayed. Depending on hardware limitations, one or more colormaps may be installed at one time, such that windows associated with those maps display with true colors. Connection The IPC path between the server and client program is known as a "connection". A client program typically (but not necessarily) has one connection to the server over which requests and events are sent. Containment A window "contains" the pointer if the window is viewable and the hotspot of the cursor is within a visible region of the window or a visible region of one of its inferiors. The border of the window is included as part of the window for containment. The pointer is "in" a window if the window contains the pointer but no inferior contains the pointer. Coordinate system The coordinate system has X horizontal and Y vertical, with the origin [0, 0] at the upper left. Coordinates are discrete, and in terms of pixels. Each window and pixmap has M.I.T. [Page 5] RFC 1013 June 1987 its own coordinate system. For a window, the origin is at the inside upper left, inside the border. Cursor A "cursor" is the visible shape of the pointer on a screen. It consist of a hot spot, a source bitmap, a shape bitmap, and a pair of colors. The cursor defined for a window controls the visible appearance when the pinter is in that window. Depth The "depth" of a window or pixmap is number of bits per pixel it has. The depth of a gcontext is the depth of the root of the gcontext. Device Keyboards, mice, tablets, track-balls, button boxes, etc. are all collectively known as input "devices". The core protocol only deals with two devices, "the keyboard" and "the pointer". Drawable Both windows and pixmaps may be used as sources and destinations in graphics operations. These are collectively known as "drawables". However, an InputOnly window cannot be used as a source or destination in a graphics operation. Event Clients are informed of information asynchronously via "events". These events may be either asynchronously generated from devices, or generated as side effects of client requests. Events are grouped into types; events are never sent to a client by the server unless the client has specificially asked to be informed of that type of event, but other clients can force events to be sent to other clients. Events are typically reported relative to a window. Event mask Events are requested relative to a window. The set of event types a client requests relative to a window described using an "event mask". Event sychronization There are certain race conditions possible when demultiplexing device events to clients (in particular deciding where pointer and keyboard events should be sent when in the middle of window management operations). The event synchronization mechanism allows synchronous processing of device events. M.I.T. [Page 6] RFC 1013 June 1987 Event propagation Device-related events "propagate" from the source window to ancestor windows until some client has expressed interest in handling that type of event, or until the event is discarded explicitly. Event source The smallest window containing the pointer is the "source" of a device related event. Exposure event Servers do not guarantee to preserve the contents of windows when windows are obscured or reconfigur contents of regions of windows have been lost. Extension Named "extensions" to the core protocol can be defined to extend the system. Extension to output requests, resources, and event types are all possible, and expected. Font A "font" is an array of glyphs (typically characters). The protocol does no translation or interpretation of character sets. The client simply indicates values used to index the glyph array. A font contains additional metric information to determine inter-glyph and inter-line spacing. Glyph A "glyph" is an image, typically of a character, in a font. Grab Keyboard keys, the keyboard, pointer buttons, the pointer, and the server can be "grabbed" for exclusive use by a client. In general, these facilities are not intended to be used by normal applications, but are intended for various input and window managers to implement various styles of user interfaces. Graphics context Various information for graphics output is stored in "GC"'s, such as foreground pixel, background pixel, line width, clipping region, etc. Hotspot A cursor has an associated "hot spot" which defines a point in the cursor that corresponds to the coordinates reported for the pointer. Identifier Each resource has an "identifier", a unique value associated with it that clients use to name the resource. An identifier M.I.T. [Page 7] RFC 1013 June 1987 can be used over any connection to name the resource. Inferiors The "inferiors" of a window are all of the subwindows nested below it: the children, the children's children, etc. Input focus The "input focus" is nominally where keyboard input goes. Keyboard events are by default sent to the client expressing interest on the window the pointer is in. This is said to be a "real estate driven" input focus. It is also possible to attach the keyboard input to a specific window; events will then be sent to the appropriate client independent of the pointer position. Input manager Control over keyboard input is typically provided by an "input manager" client. InputOnly window A window that cannot be used for graphics requests. InputOnly windows are "invisible", and can be used to control such things as cursors, input event generation, and grabbing. InputOutput window The "normal" kind of opaque window, used for both input and output. Key grabbing Keys on the keyboard may be passively "grabbed" by a client. When the key is pressed, the keyboard is then actively grabbed by the client. Keyboard grabbing A client can actively "grab" control of the keyboard, and key events will be sent to that client rather than the client the events would normally have been sent to. Mapping A window is said to be "mapped" if a map call has been performed on it. Unmapped windows are never viewable or visible. Modifier keys Shift, Control, Meta, Super, Hyper, ALT, Compose, Apple, CapsLock, ShiftLock, and similar keys are called "modifier" keys. Obscures Window A "obscures" window B if both are viewable InputOutput windows and A is higher in the global stacking M.I.T. [Page 8] RFC 1013 June 1987 order, and the rectangle defined by the outside edges of intersects the rectangle defined by the outside edges of B. Note the (fine) distinction with "occludes". Also note that window borders are included in the calculation. Occludes Window A "occludes" window B if both are mapped and A is higher in the global stacking order, and the rectangle defined by the outside edges of A intersects the rectangle defined by the outside edges of B. Note the (fine) distinction with "obscures". Also note that window borders are included in the calculation. Padding Some padding bytes are inserted in the data stream to maintain alignment of the protocol requests on natural boundaries. This increases ease of portability to some machine architectures. Parent window If C is a child of P, then P is the "parent" of C. Passive grab Grabbing a key or button is a "passive" grab. The grab activates when the key or button is actually pressed. Pixel value A "pixel" is an N-bit value, where N is the number of bit planes used in a particular window or pixmap. For a window, a pixel value indexes a colormap to derive an actual color to be displayed. Pixmap A "pixmap" is a three dimensional array of bits. A pixmap is normally thought of as a two dimensional array of pixels, where each pixel can be a value from 0 to (2^N)-1, where N is the depth (z axis) of the pixmap. A pixmap can also be thought of as a stack of N bitmaps. Plane mask Graphics operations can be restricted to only affect a subset of bit planes of a destination. A "plane mask" is a bit mask describing which planes are to be modified, and is stored in a graphics context. Pointer The "pointer" is the pointing device attached to the cursor, and tracked on the screens. Pointer grabbing A client can actively "grab" control of the pointer, and M.I.T. [Page 9] RFC 1013 June 1987 button and motion events will be sent to that client rather than the client the events would normally have been sent to. Pointing device A "pointing device" is typically a mouse or tablet, or some other device with effective dimensional motion. There is only one visible cursor is defined by the core protocol, and it tracks whatever pointing device is attached as the pointer. Property Windows may have associated "properties", consisting of a name, a type, a data format, and some data. The protocol places no interpretation on properties, they are intended as a general-purpose naming mechanism for clients. For example, clients might share information such as resize hints, program names, and icon formats with a window manager via properties. Property list The "property list" of a window is the list of properties that have been defined for the window. Redirecting control Window managers (or client programs) may wish to enforce window layout policy in various ways. When a client attempts to change the size or position of a window, the operation may be "redirected" to a specified client, rather than the operation actually being performed. Reply Information requested by a client program is sent back to the client with a "reply". Both events and replys are multipexed on the same connection. Most requests do not generate replies. Request A command to the server is called a "request". It is a single block of data sent over a connection. Resource Windows, pixmaps, cursors, fonts, graphics contexts, and colormaps are known as "resources". They all have unique identifiers associated with them for naming purposes. The lifetime of a resource is bounded by the lifetime of the connection over which the resource was created. Root The "root" of a pixmap or gcontext is the same as the root of whatever drawable was used when the pixmap or gcontext was created. The "root" of a window is the root window M.I.T. [Page 10] RFC 1013 June 1987 under which the window was created. Root window Each screen has a "root window" covering it. It cannot be reconfigured or unmapped, but otherwise acts as a full fledged window. A root window has no parent. Save set The "save set" of a client is a list of other client's windows which, if they are inferiors of one of the client's windows at connection close, should not be destroyed, and which should be remapped if it is unmapped. Save sets are typically used by window managers to avoid lost windows if the manager should terminate abnormally. Screen A server may provide several independent "screens", which typically have physically independent monitors. This would be the expected configuration when there is only a single keyboard and pointer shared among the screens. Server The "server" provides the basic windowing mechanism. It handles IPC connections from clients, demultipexes graphics requests onto the screens, and multiplexes input back to the appropriate clients. Server grabbing The server can be "grabbed" by a single client for exclusive use. This prevents processing of any requests from other client connections until the grab is complete. This is typically only a transient state for such things as rubber-banding and pop-up menus, or to execute requests indivisibly. Sibling Children of the same parent window are known as "sibling" windows. Stacking order Sibling windows may "stack" on top of each other. Windows above both obscure and occlude lower windows. This is similar to paper on a desk. The relationship between sibling windows is known as the "stacking order". Stipple A "stipple pattern" is a bitmap that is used to tile a region to serve as an additional clip mask for a fill operation with the foreground color. M.I.T. [Page 11] RFC 1013 June 1987 Tile A pixmap can be replicated in two dimensions to "tile" a region. The pixmap itself is also known as a "tile". Timestamp A time value, expressed in milliseconds, typically since the last server reset. Timestamp values wrap around (after about 49.7 days). The server, given its current time is represented by timestamp T, always interprets timestamps from clients by treating half of the timestamp space as being earlier in time than T, and half of the timestamp space as being later in time than T. One timestamp value (named CurrentTime) is never generated by the server; this value is reserved for use in requests to represent the current server time. Type A type is an arbitrary atom used to identify the interpretation of property data. Types are completely uninterpreted by the server; they are solely for the benefit of clients. Unviewable A window is "unviewable" if it is mapped but some ancestor is unmapped. Viewable A window is "viewable" if it and all of its ancestors are mapped. This does not imply that any portion of the window is actually visible. Visible A region of a window is "visible" if someone looking at the screen can actually "see" it: the window is viewable and the region is not occluded by any other window. Window gravity When windows are resized, subwindows may be repositioned automatically relative to some position in the window. This attraction of a subwindow to some part of its parent is known as "window gravity". Window manager Manipulation of windows on the screen, and much of the user interface (policy) is typically provided by a "window manager" client. XYFormat The data for a pixmap is said to be in "XYFormat" if it is organized as a set of bitmaps representing individual bit planes. M.I.T. [Page 12] RFC 1013 June 1987 ZFormat The data for a pixmap is said to be in "ZFormat" if it is organized as a set of pixel values in scanline order. SECTION 2. PROTOCOL FORMATS Request Format Every request contains an 8-bit "major" opcode, and a 16-bit length field expressed in units of 4 bytes. Every request consists of 4 bytes of header containing the major opcode, the length field, and a data byte) followed by zero or more additional bytes of data; the length field defines the total length of the request, including the header. The length field in a request must equal the minimum length required to contain the request; if the specified length is smaller or larger than the required length, an error is enerated. Unused bytes in a request are not required to be zero. Major opcodes 128 through 255 are reserved for extensions. Extensions are intended to contain multiple requests, so extension requests typically have an additional minor opcode encoded in the "spare" data byte in the request header, but the placement and interpretation of this minor opcode, and all other fields in extension requests, are not defined by the core protocol. Every request is implicitly assigned a sequence number, starting with one,used in replies, errors, and events. Reply Format Every reply contains a 32-bit length field expressed in units of 4 bytes. Every reply consists of 32 bytes, followed by zero or more additional bytes of data, as specified in the length field. Unused bytes within a reply are not guaranteed to be zero. Every reply also contains the least significant 16 bits of the sequence number of the corresponding request. Error Format Error reports are 32 bytes long. Every error includes an 8-bit error code. Error codes 128 through 255 are reserved for extensions. Every error also includes the major and minor opcodes of the failed request, and the least significant 16 bits of the sequence number of the request. For the following errors (see Section 5), the failing resource id is also returned: Colormap, Cursor, Drawable, Font, GContext, IDChoice, Pixmap, and Window. For Atom errors, the failing atom is returned. For Value errors, the failing value is returned. Other core errors return no additional data. Unused bytes within an error are not guaranteed to be zero. Event Format Events are 32 bytes long. Unused bytes within an event are not M.I.T. [Page 13] RFC 1013 June 1987 guaranteed to be zero. Every event contains an 8-bit type code. The most significant bit in this code is set if the event was generated from a SendEvent request. Event codes 64 through 127 are reserved for extensions, although the core protocol does not define a mechanism for selecting interest in such events. Every core event (with the exception of KeymapNotify) also contains the least significant 16 bits of the sequence number of the last request issued by the client that was (or is currently being) processed by the server. SECTION 3. SYNTAX The syntax {...} encloses a set of alternatives. The syntax [...] encloses a set of structure components. In general, TYPEs are in upper case and AlternativeValues are capitalized. Requests in Section 10 are described in the following format: RequestName arg1: type1 ... argN: typeN => result1: type1 ... resultM: typeM Errors: kind1, ..., kindK Description. If no => is present in the description, then the request has no reply (it is asynchronous), although errors may still be reported. Events in Section 12 are described in the following format: EventName value1: type1 ... valueN: typeN Description. M.I.T. [Page 14] RFC 1013 June 1987 SECTION 4. COMMON TYPES LISTofFOO A type name of the form LISTofFOO means a counted list of elements of type FOO; the size of the length field may vary (it is not necessarily the same size as a FOO), in some cases may be implicit, and is not fully specified in this document. BITMASK and LISTofVALUE The types BITMASK and LISTofVALUE are somewhat special. Various requests contain arguments of the form: value-mask: BITMASK value-list: LISTofVALUE used to allow the client to specify a subset of a heterogeneous collection of "optional" arguments. The value-mask specifies which arguments are to be provided; each such argument is assigned a unique bit position. The representation of the BITMASK will typically contain more bits than there are defined arguments; unused bits in the value-mask must be zero (or the server generates a Value error). The value-list contains one value for each one bit in the mask, from least to most significant bit in the mask. Each value is represented with 4 bytes, but the actual value occupies only the least significant bytes as required; the values of the unused bytes do not matter. Or Types A type of the form "T1 or ... or Tn" means the union of the indicated types; a single-element type is given as the element without enclosing braces. DEVICE: 32-bit id (<class,model,manufacturer,unit> 8 bits each) WINDOW: 32-bit id PIXMAP: 32-bit id CURSOR: 32-bit id FONT: 32-bit id GCONTEXT: 32-bit id COLORMAP: 32-bit id DRAWABLE: WINDOW or PIXMAP ATOM: 32-bit id (top 3 bits guaranteed to be zero) VISUALID: 32-bit id (top 3 bits guaranteed to be zero) VALUE: 32-bit quantity (used only in LISTofVALUE) INT8: 8-bit signed integer INT16: 16-bit signed integer INT32: 32-bit signed integer CARD8: 8-bit unsigned integer CARD16: 16-bit unsigned integer CARD32: 32-bit unsigned integer M.I.T. [Page 15] RFC 1013 June 1987 TIMESTAMP: CARD32 BITGRAVITY: {Forget, Static, NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast} WINGRAVITY: {Unmap, Static, NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast} BOOL: {True, False} EVENT: {KeyPress, KeyRelease, OwnerGrabButton, ButtonPress, ButtonRelease, EnterWindow, LeaveWindow, PointerMotion, PointerMotionHint, Button1Motion, Button2Motion, Button3Motion, Button4Motion, Button5Motion, ButtonMotion Exposure, VisibilityChange, StructureNotify, ResizeRedirect, SubstructureNotify, SubstructureRedirect, FocusChange, PropertyChange, ColormapChange, KeymapState} POINTEREVENT: {ButtonPress, ButtonRelease, EnterWindow, LeaveWindow, PointerMotion, PointerMotionHint, Button1Motion, Button2Motion, Button3Motion, Button4Motion, Button5Motion, ButtonMotion KeymapState} DEVICEEVENT: {KeyPress, KeyRelease, ButtonPress, ButtonRelease, PointerMotion, Button1Motion, Button2Motion, Button3Motion, Button4Motion, Button5Motion, ButtonMotion} KEYCODE: CARD8 BUTTON: CARD8 KEYMASK: {Shift, CapsLock, Control, Mod1, Mod2, Mod3, Mod4, Mod5} BUTMASK: {Button1, Button2, Button3, Button4, Button5} KEYBUTMASK: KEYMASK or BUTMASK STRING8: LISTofCARD8 STRING16: LISTofCHAR2B CHAR2B: [byte1, byte2: CARD8] POINT: [x, y: INT16] RECTANGLE: [x, y: INT16, width, height: CARD16] ARC: [x, y: INT16, width, height: CARD16, angle1, angle2: INT16] HOST: [family: {Internet, NS, ECMA, Datakit, DECnet} address: LISTofCARD8] The [x,y] coordinates of a RECTANGLE specify the upper left corner. M.I.T. [Page 16] RFC 1013 June 1987 The primary interpretation of "large" characters in a STRING16 is that they are composed of two bytes used to index a 2-D matrix; hence the use of CHAR2B rather than CARD16. This corresponds to the JIS/ISO method of indexing two-byte characters. It is expected that most "large" fonts will be defined with two-byte matrix indexing. For large fonts constructed with linear indexing, a CHAR2B can be interpreted as a 16-bit number by treating byte1 as the most significant byte; this means that clients should always transmit such 16-bit character values most significant byte first, as the server will never byte-swap CHAR2B quantities. The length, format, and interpretation of a HOST address are specific to the family. SECTION 5. ERRORS In general, when a request terminates with an error, the request has no side effects (i.e., there is no partial execution). The only requests for which this is not true are ChangeWindowAttributes, ChangeGC, PolyText8, PolyText16, FreeColors, StoreColors, and ChangeKeyboardControl. The following error codes can be returned by the various requests: Access An attempt to grab a key/button combination already grabbed by another client. An attempt to free a colormap entry not allocated by the client. An attempt to store into a read-only or an unallocated colormap entry. An attempt to modify the access control list from other than the local (or otherwise authorized) host. An attempt to select an event type, that at most one client can select at a time, when another client has already selected it. Alloc The server failed to allocate the requested resource. Note that this only covers allocation errors at a very coarse level, and is not intended to (nor can it in practice hope to) cover all cases of a server running out of allocation space in the middle of service. M.I.T. [Page 17] RFC 1013 June 1987 The semantics when a server runs out of allocation space are left unspecified. Atom A value for an ATOM argument does not name a defined ATOM. Colormap A value for a COLORMAP argument does not name a defined COLORMAP. Cursor A value for a CURSOR argument does not name a defined CURSOR. Drawable A value for a DRAWABLE argument does not name a defined WINDOW or PIXMAP. Font A value for a FONT or <FONT or GCONTEXT> argument does not name a defined FONT. GContext A value for a GCONTEXT argument does not name a defined GCONTEXT. IDChoice The value chosen for a resource identifier is either not included in the range assigned to the client, or is already in use. Implementation The server does not implement some aspect of the request. A server which generates this error for a core request is deficient. As such, this error is not listed for any of the requests, but clients should be prepared to receive such errors, and handle or discard them. Length The length of a request is shorter or longer than that required to minimally contain the arguments. Match An InputOnly window is used as a DRAWABLE. Some argument (or pair of arguments) has the correct type and range, but fails to "match" in some other way required by the request. Name A font or color of the specified name does not exist. M.I.T. [Page 18] RFC 1013 June 1987 Pixmap A value for a PIXMAP argument does not name a defined PIXMAP. Property The requested property does not exist for the specified window. Request The major or minor opcode does not specify a valid request. Value Some numeric value falls outside the range of values accepted by the request. Unless a specific range is specified for an argument, the full range defined by the argument's type is accepted. Any argument defined as a set of alternatives can generate this error. Window A value for a WINDOW argument does not name a defined WINDOW. Note: the Atom, Colormap, Cursor, Drawable, Font, GContext, Pixmap, and Window errors are also used when the argument type is extended by union with a set of fixed alternatives, e.g.,<Window or PointerRoot or None>. SECTION 6. KEYBOARDS Keycodes are always in the inclusive range [8,255]. For keyboards with both left-side and right-side modifier keys (e.g., Shift and Control), the mask bits in the protocol always define the OR of the keys. If electronically distinguishable, they can have separate up/down events generated, and clients that want to distinguish can track the individual states manually. <As part of the core we need to define a universal association between keycaps and keycodes. A keycap is the graphical information imprinted on a keyboard key, e.g., "$ 4", "T", "+ =".> SECTION 7. POINTERS Buttons are always numbered starting with one. SECTION 8. PREDEFINED ATOMS Predefined atoms are not strictly necessary, and may not be useful in all environments, but will eliminate many InternAtom requests in most applications. The core protocol imposes no semantics on these names, M.I.T. [Page 19] RFC 1013 June 1987 except as they are used in FONTPROP structures (see QueryFont). Note that upper/lower case matters. BITMAP ICON_SIZE RGB_GREEN_MAP COMMAND ITALIC_ANGLE RGB_RED_MAP COPYRIGHT MAX_SPACE SECONDARY CUT_BUFFER0 MIN_SPACE SIZE_HINTS CUT_BUFFER1 NAME STRIKEOUT_ASCENT CUT_BUFFER2 NORMAL_HINTS STRIKEOUT_DESCENT CUT_BUFFER3 NORM_SPACE STRING CUT_BUFFER4 PIXMAP SUBSCRIPT_X CUT_BUFFER5 POINT_SIZE SUBSCRIPT_Y CUT_BUFFER6 PRIMARY SUPERSCRIPT_X CUT_BUFFER7 QUAD_WIDTH SUPERSCRIPT_Y DEFAULT_CHAR RECTANGLE UNDERLINE_POSITION END_SPACE RESIZE_HINT UNDERLINE_THICKNESS FACE_NAME RESOLUTION WEIGHT FAMILY_NAME RGB_BEST_MAP WINDOW FONT_ASCENT RGB_BLUE_MAP WM_HINTS FONT_DESCENT RGB_COLOR_MAP X_HEIGHT ICON RGB_DEFAULT_MAP ZOOM_HINTS ICON_NAME SECTION 9. CONNECTION SETUP For remote clients, the X protocol can be built on top of any reliable byte stream. For TCP connections, displays on a given host a numbered starting from 0, and the server for display N listens and accepts connections on port 6000+N. The client must send an initial byte of data to identify the byte order to be employed. The value of the byte must be octal 102 or 154. The value 102 (ASCII uppercase B) means values are transmitted most significant byte first, and value 154 (ASCII lowercase l) means values are transmitted least significant byte first. Except where explicitly noted in the protocol, all 16-bit and 32-bit quantities sent by the client must be transmitted with this byte order, and all 16-bit and 32-bit quantities returned by the server will be transmitted with this byte order. Following the byte-order byte, the following information is sent by the client at connection setup: protocol-major-version: CARD16 protocol-minor-version: CARD16 authorization-protocol-name: STRING8 authorization-protocol-data: STRING8 The version numbers indicate what version of the protocol the client expects the server to implement. See below for an M.I.T. [Page 20] RFC 1013 June 1987 explanation. The authorization name indicates what authorization protocol the client expects the server to use, and the data is specific to that protocol. Specification of valid authorization mechanisms is not part of the core X protocol. It is hoped that eventually one authorization protocol will be agreed upon. In the mean time, a server that implements a different protocol than the client expects, or a server that only implements the host-based mechanism, will simply ignore this information. Received by the client at connection setup: success: BOOL protocol-major-version: CARD16 protocol-minor-version: CARD16 length: CARD16 Length is the amount of additional data to follow, in units of 4 bytes. The version numbers are an escape hatch in case future revisions of the protocol are necessary. In general, the major version would increment for incompatible changes, and the minor version would increment for small upward compatible changes. Barring changes, the major version will be eleven, and the minor version will be zero. The protocol version numbers returned indicate the protocol the server actually supports. This might not equal the version sent by the client. The server can (but need not) refuse connections from clients that offer a different version than the server supports. A server can (but need not) support more than one version simultaneously. Additional data received if authorization fails: reason: STRING8 Additional data received if authorization is accepted: vendor: STRING8 release-number: CARD32 resource-id-base, resource-id-mask: CARD32 image-byte-order: {LSBFirst, MSBFirst} bitmap-format-scanline-unit: {8, 16, 32} bitmap-format-scanline-pad: {8, 16, 32} bitmap-format-bit-order: {LeastSignificant, MostSignificant} pixmap-formats: LISTofFORMAT roots: LISTofSCREEN keyboard: DEVICE pointer: DEVICE motion-buffer-size: CARD32 maximum-request-length: CARD16 where FORMAT: [depth: CARD8, M.I.T. [Page 21] RFC 1013 June 1987 bits-per-pixel: {4, 8, 16, 24, 32} scanline-pad: {8, 16, 32}] SCREEN: [root: WINDOW device: DEVICE width-in-pixels, height-in-pixels: CARD16 width-in-millimeters,height-in-millimeters:CARD16 allowed-depths: LISTofDEPTH root-depth: CARD8 root-visual: VISUALID default-colormap: COLORMAP white-pixel, black-pixel: CARD32 min-installed-maps, max-installed-maps: CARD16 backing-stores: {Never, WhenMapped, Always} save-unders: BOOL current-input-masks: SETofEVENT] DEPTH: [depth: CARD8 visuals: LISTofVISUALTYPE] VISUALTYPE: [visual-id: VISUALID class: {StaticGray, StaticColor, TrueColor,GrayScale, PseudoColor, DirectColor} red-mask, green-mask, blue-mask: CARD32 bits-per-rgb-value: CARD8 colormap-entries: CARD16] Per server information: The vendor string gives some indentification of the owner of the server implementation. The semantics of the release-number is controlled by the vendor. The resource-id-mask contains a single contiguous set of bits (at least 18); the client allocates resource ids by choosing a value with (only) some subset of these bits set, and ORing it with resource-id-base. Only values constructed in this way can be used to name newly created resources over this connection. Resource ids never have the top 3 bits set. The client is not restricted to linear or contiguous allocation of resource ids. Once an id has been freed, it can be reused, but this should not be necessary. An id must be unique with respect to the ids of all other resources, not just other resources of the same type. Although the server is in general responsible for byte swapping data to match the client, images are always transmitted and received in formats (including byte order) specified by the server. The byte order for images is given by image-byte-order, and applies to each scanline unit in XYFormat (bitmap) format, and to each pixel value in ZFormat. A bitmap is represented in scanline order. Each scanline is padded to a multiple of bits as given by bitmap-format-scanline-pad. The M.I.T. [Page 22] RFC 1013 June 1987 pad bits are of arbitrary value. The scanline is quantized in multiples of bits as given by bitmap-format-scanline-unit. Within each unit, the leftmost bit in the bitmap is either the least or most significant bit in the unit, as given by bitmap-format-bit-order. If a pixmap is represented in XYFormat, each plane is represented as a bitmap, and the planes appear from most to least significant in bit order. For each pixmap depth supported by some screen, pixmap-formats lists the ZFormat used to represent images of that depth. In ZFormat, the pixels are in scanline order, left to right within a scanline. The number of bits used to hold each pixel is given by bits-per-pixel, and may be larger than strictly required by the depth. When the bits-per-pixel is 4, the order of nibbles in the byte is the same as the image byte-order. Each scanline is padded to a multiple of bits as given by scanline-pad. How a pointing device roams the screens is up to the server implementation, and is transparent to the protocol. No geometry among screens is defined. The server may retain the recent history of pointer motion, and to a finer granularity than is reported by MotionNotify events. Such history is available via the GetPointerMotions request. The approximate size of the history buffer is given by motion-buffer-size. Maximum-request-length specifies the maximum length of a request, in 4-byte units, accepted by the server; i.e., this is the maximum value that can appear in the length field of a request. Requests larger than this generate a Length error, and the server will read and simply discard the entire request. Maximum-request-length will always be at least 4096 (i.e., requests of length up to and including 16384 bytes will be accepted by all servers). Per screen information: The allowed-depths specifies what pixmap and window depths are supported. Pixmaps are supported for each depth listed, and windows of that depth are supported if at least one visual type is listed for the depth. A pixmap depth of one is always supported and listed, but windows of depth one might not be supported. A depth of zero is never listed, but zero-depth InputOnly windows are always supported. Root-depth and root-visual specify the depth and visual type of the root window. Width-in-pixels and height-in-pixels specify the size of the root window (which cannot be changed). The class of the root window is always InputOutput. Width-in-millimeters and height-in-millimeters can be used to determine the physical size and the aspect ratio. M.I.T. [Page 23] RFC 1013 June 1987 The default-colormap is the one initially associated with the root window. Clients with minimal color requirements creating windows of the same depth as the root may want to allocate from this map by default. Black-pixel and white-pixel can be used in implementing a "monochrome" application. These pixel values are for permanently allocated entries in the default-colormap; the actual RGB values may be settable on some screens. The border of the root window is initially a pixmap filled with the black-pixel. The initial background of the root window is a pixmap filled with some unspecified two-color pattern using black-pixel and white-pixel. Min-installed-maps specifies the number of maps that can be guaranteed to installed simultaneously (with InstallColormap), regardless of the number of entries allocated in each map. Max-installed-maps specifies the maximum number of maps that might possibly be installed simultaneously, depending on their allocations. For the typical case of a single hardware colormap, both values will be one. Backing-stores indicates when the server supports backing stores for this screen, although it may be storage limited in the number of windows it can support at once. If save-unders is True, then the a server can support the save-under mode in CreateWindow and ChangeWindowAttributes, although again it may be storage limited. The current-input-events is what GetWindowAttributes would return for the all-event-masks for the root window. Per visual-type information: A given visual type might be listed for more than one depth, or for more than one screen. For PseudoColor, a pixel value indexes a colormap to produce independent RGB values; the RGB values can be changed dynamically. GrayScale is treated the same as PseudoColor, except which primary drives the screen is undefined, so the client should always store the same value for red, green, and blue in colormaps. For DirectColor, a pixel value is decomposed into separate RGB subfields, and each subfield separately indexes the colormap for the corresponding value; The RGB values can be changed dynamically. TrueColor is treated the same as DirectColor, except the colormap has predefined read-only RGB values, which are server-dependent, but provide (near-)linear ramps in each primary. StaticColor is treated the same as PseudoColor, except the colormap has predefined read-only RGB values, which are server-dependent. StaticGray is treated the same as StaticColor, except the red, M.I.T. [Page 24] RFC 1013 June 1987 green, and blue values are equal for any single pixel value, resulting in shades of gray. StaticGray with a two-entry colormap can be thought of as "monochrome". The red-mask, green-mask, and blue-mask are only defined for DirectColor and TrueColor; each has one contiguous set of bits, with no intersections. The bits-per-rgb-value specifies the log base 2 of the approximate number of distinct color values (individually) of red, green, and blue. Actual RGB values are always passed in the protocol within a 16-bit spectrum. The colormap-entries defines the number of available colormap entries in a newly created colormap. For DirectColor and TrueColor, this will usually be the size of an individual pixel subfield. SECTION 10. REQUESTS CreateWindow wid, parent: WINDOW class: {InputOutput, InputOnly, CopyFromParent} depth: CARD8 visual: VISUALID or CopyFromParent x, y: INT16 width, height, border-width: CARD16 value-mask: BITMASK value-list: LISTofVALUE Errors: IDChoice, Window, Pixmap, Colormap, Cursor, Match, Value, Alloc Creates an unmapped window, and assigns the identifier wid to it. A class of CopyFromParent means the class is taken from the parent. A depth of zero for class InputOutput or CopyFromParent means the depth is taken from the parent. A visual of CopyFromParent means the visual type is taken from the parent. For class InputOutput, the visual type and depth must be a combination supported for the screen (else a Match error); the depth need not be the same as the parent, but the parent must not be of class InputOnly (else a Match error). For class InputOnly, the depth must be zero (else a Match error), and the visual must be one supported for the screen (else a Match error), but the parent may have any depth and class. The server essentially acts as if InputOnly windows do not exist for the purposes of graphics requests, exposure M.I.T. [Page 25] RFC 1013 June 1987 processing, and VisibilityNotify events. An InputOnly window cannot be used as a drawable (as a source or destination for graphics requests). InputOnly and InputOutput windows act identically in other respects (properties, grabs, input control, and so on). The window is placed on top in the stacking order with respect to siblings. The x and y coordinates are relative to the parent's origin, and specify the position of the upper left outer corner of the window (not the origin). The width and height specify the inside size, not including the border, and must be non-zero. The border-width for an InputOnly window must be zero (else a Match error). The value-mask and value-list specify attributes of the window that are to be explicitly initialized. The possible values are: background-pixmap: PIXMAP or None or ParentRelative background-pixel: CARD32 border-pixmap: PIXMAP or CopyFromParent border-pixel: CARD32 bit-gravity: BITGRAVITY win-gravity: WINGRAVITY backing-store: {NotUseful, WhenMapped, Always} backing-bit-planes: CARD32 backing-pixel: CARD32 save-under: BOOL event-mask: SETofEVENT do-not-propagate-mask: SETofDEVICEEVENT override-redirect: BOOL colormap: COLORMAP or CopyFromParent cursor: CURSOR or None The default values, when attributes are not explicitly initialized, are: background-pixmap: None border-pixmap: CopyFromParent bit-gravity: Forget win-gravity: NorthWest backing-store: NotUseful backing-bit-planes: all ones backing-pixel: zero save-under: False event-mask: {} (empty set) do-not-propagate-mask: {} (empty set) override-redirect: False colormap: CopyFromParent cursor: None M.I.T. [Page 26] RFC 1013 June 1987 Only the following attributes are defined for InputOnly windows: win-gravity, event-mask, do-not-propagate-mask, and cursor. It is a Match error to specify any other attributes for InputOnly windows. If background-pixmap is given, it overrides the default background-pixel. The background pixmap and the window must have the same root and the same depth (else a Match error). Any size pixmap can be used, although some sizes may be faster than others. If background None is specifed, the window has no defined background. If background ParentRelative is specified, the parent's background is used, but the window must have the same depth as the parent (else a Match error); if the parent has background None, then the window will also have background None. A copy of the parent's background is not made; the parent's background is reexamined each time the window background is required. If background-pixel is given, it overrides the default and any background-pixmap given, and a pixmap of undefined size filled with background-pixel is used for the background. For a ParentRelative background, the background tile origin always aligns with the parent's background tile origin; otherwise the background tile origin is always the window origin. When regions of the window are exposed and the server has not retained the contents, the server automatically tiles the regions with the window's background unless the window has a background of None, in which case the previous screen contents are simply left in place. Exposure events are then generated for the regions, even if the background is None. The border tile origin is always the same as the background tile origin. If border-pixmap is given, it overrides the default border-pixel. The border pixmap and the window must have the same root and the same depth (else a Match error). Any size pixmap can be used, although some sizes may faster than others. If CopyFromParent is given, the parent's border pixmap is copied (subsequent changes to the parent do not affect the child), but the window must have the same depth as the parent (else a Match error). If border-pixel is given, it overrides the default and any border-pixmap given, and a pixmap of undefined size filled with border-pixel is used for the border. Output to a window is always clipped to the inside of the window, so that the border is never affected. The bit-gravity defines which region of the window should be retained if the window is resized, and win-gravity defines how the window should be repositioned if the parent is M.I.T. [Page 27] RFC 1013 June 1987 resized; see ConfigureWindow. A backing-store of WhenMapped advises the server that maintaining contents of obscured regions when the window is mapped would be beneficial. A backing-store of Always advises the server that maintaining contents even when the window is unmapped would be beneficial. Note that, even if the window is larger than its parent, the server should maintain complete contents, not just the region within the parent boundaries. If the server maintains contents, Exposure events will not be generated, but the server may stop maintaining contents at any time. A value of NotUseful advises the server that maintaining contents is unnecessary, although a server may still choose to maintain contents. Backing-bit-planes indicates (with one bits) which bit planes of the window hold dynamic data that must be preserved in backing-stores. Backing-pixel specifies what value to use in planes not covered by backing-bit-planes. The server is free to only save the specified bit planes in the backing-store, and regenerate the remaining planes with the specified pixel value. If save-under is True, the server is advised that, when this window is mapped, saving the contents of windows it obscures would be beneficial. The event-mask defines which events the client is interested in for this window (or, for some event types, inferiors of the window). The do-not-propagate-mask defines which events should not be propagated to ancestor windows when no client has the event type selected in this window. Override-redirect specifies whether map and configure request on this window should override a SubstructureRedirect on the parent, typically to inform a window manager not to tamper with the window. The colormap specifies the colormap, that best reflects the "true" colors of the window. Servers capable of supporting hardware colormaps may use this information, and window managers may use it for InstallColormap requests. The colormap must have the same visual type as the window (else a match error). If CopyFromParent is specified, the parents's colormap is copied (subsequent changes to the parent do not affect the child), but the window must have the same visual type as the parent (else a Match error) an the parent must not have a colormap of None (else a Match error). M.I.T. [Page 28] RFC 1013 June 1987 If a cursor is specified, it will be used whenever the pointer is in the window. If None is specified, the parent's cursor will be used when the pointer is in the window, and any change in the parent's cursor will cause an immediate change in the display cursor. This request generates a CreateNotify event. The background and border pixmaps and the cursor may be freed immediately if no further explicit references to them are to be made. Subsequent drawing into the background or border pixmap has an undefined effect on the window state; the server might or might not make a copy of the pixmap. ChangeWindowAttributes window: WINDOW value-mask: BITMASK value-list: LISTofVALUE Errors: Window, Pixmap, Colormap, Cursor, Match, Value, Access The value-mask and value-list specify which attributes are to be changed. The values and restrictions are the same as for CreateWindow. Changing the background does not cause the window contents to be changed. Setting the border, or changing the background such that border tile origin changes, causes the border to be repainted. Changing the background of a root window to None or ParentRelative restores the default background pixmap. Changing the border of a root window to CopyFromParent restores the default border pixmap. Changing the back-store of an obsecured window to WhenMapped or Always, or changing the backing-bit-planes, backing-pixel, or save-under of a mapped window, may have no immediate effect. Multiple clients can select input on the same window; their event-masks are disjoint. When an event is generated it will be reported to all interested clients. However, at most one client at a time can select for SubstructureRedirect, at most one client at a time can select for ResizeRedirectr, and at most one client at a time can select for ButtonPress. There is only one do-not-propagate-mask for a window, not one per client. M.I.T. [Page 29] RFC 1013 June 1987 Changing the colormap of a window (i.e., defining a new map, not changing the contents of the existing map) generates a ColormapNorify event. Changing the colormap os a visible window may have no immediate effect on the screen; see InstallColormap. Changing the cursor of a root window to None restores the default cursor. The order in which attributes are verified and altered is server dependent. If an error is generated, a subset of the attributes may have been altered. GetWindowAttributes window: WINDOW => visual: VISUALID class: {InputOutput, InputOnly} bit-gravity: BITGRAVITY win-gravity: WINGRAVITY backing-store: {NotUseful, WhenMapped, Always} backing-bit-planes: CARD32 backing-pixel: CARD32 save-under: BOOL colormap: COLORMAP or None map-is-installed: BOOL map-state: {Unmapped, Unviewable, Viewable} all-event-masks, your-event-mask: SETofEVENT do-not-propagate-mask: SETofDEVICEEVENT override-redirect: BOOL Errors: Window Returns current attributes of the window. All-event-masks is the inclusive-OR of all event masks selected on the window by clients. Your-event-mask is the event mask selected by the querying client. DestroyWindow window: WINDOW Errors: Window If the argument window is mapped, an UnmapWindow request is performed automatically. The window and all inferiors are then destroyed, and a DestroyNotify event is generated for each window, in order from the argument window downwards, with unspecified order among siblings at each level. Normal exposure processing on formerly obscured windows is performed. M.I.T. [Page 30] RFC 1013 June 1987 If the window is a root window, this request has no effect. DestroySubwindows window: WINDOW Errors: Window Performs a DestroyWindow on all children of the window, in bottom to top stacking order. ChangeSaveSet window: WINDOW mode: {Insert, Delete} Errors: Window, Match, Value Adds or removes the specified window from the client's "save-set". The window must have been created by some other client (else a Match error). The use of the save-set is described in Section 11. Windows are removed automatically from the save-set by the server when they are destroyed. ReparentWindow window, parent: WINDOW x, y: INT16 Errors: Window, Match If the window is mapped, an UnmapWindow request is performed automatically first. The window is then removed from its current position in the hierarchy, and is inserted as a child of the specified parent. The x and y coordinates are relative to the parent's origin, and specify the new position of the upper left outer corner of the window. The window is placed on top in the stacking order with respect to siblings. A ReparentNotify event is then generated. The override-redirect attribute of the window is passed on in this event; a value of True indicates that a window manager should not tamper with this window. Finally, if the window was originally mapped, a MapWindow request is performed automatically. Normal exposure processing on formerly obscured windows is performed. The server might not generate exposure events for regions from the initial unmap that are immediately obscured by the final map. A Match error is generated if the new parent is not on the same screen as the old parent, or if the new parent is the M.I.T. [Page 31] RFC 1013 June 1987 window itself or an inferior of the window, or if the window has a ParentRelative background and the new parent is not the same depth as the window. MapWindow window: WINDOW Errors: Window If the window is already mapped, this request has no effect. If the override-redirect attribute of the window is False and some other client has selected SubstructureRedirect on the parent, then a MapRequest event is generated, but the window remains unmapped. Otherwise, the window is mapped and a MapNotify event is generated. If the window is now viewable and its contents had been discarded, then the window is tiled with its background (if no background is defined the existing screen contents are not altered) and one or more exposure events are generated. If a backing-store has been maintained while the window was unmapped, no exposure events are generated. If a backing-store will now be maintained, a full-window exposure is always generated; otherwise only visible regions may be reported. Similar tiling and exposure take place for any newly viewable inferiors. MapSubwindows window: WINDOW Errors: Window Performs a MapWindow request on all unmapped children of the window, in top to bottom stacking order. UnmapWindow window: WINDOW Errors: Window If the window is already unmapped, this request has no effect. Otherwise, the window is unmapped and an UnmapNotify event is generated. Normal exposure processing on formerly obscured windows is performed. UnmapSubwindows window: WINDOW Errors: Window M.I.T. [Page 32] RFC 1013 June 1987 Performs an UnmapWindow request on all mapped children of the window, in bottom to top stacking order. ConfigureWindow window: WINDOW value-mask: BITMASK value-list: LISTofVALUE Errors: Window, Match, Value Changes the configuration of the window. The value-mask and value-list specify which values are to be given. The possible values are: x: INT16 y: INT16 width: CARD16 height: CARD16 border-width: CARD16 sibling: WINDOW stack-mode: {Above, Below, TopIf, BottomIf, Opposite} The x and y coordinates are relative to the parent's origin, and specify the position of the upper left outer corner of the window. The width and height specify the inside size, not including the border, and must be non-zero. It is a Match error to attempt to make the border-width of an InputOnly window non-zero. If the override-redirect attribute of the window is False and some other client has selected SubstructureRedirect on the parent, then a ConfigureRequest event is generated, and no further processing is performed. Otherwise, the following is performed. If some other client has selected ResizeRedirect on the window and the width or height of the window is being changed, then a ResizeRequest event is generated, and the current width and height are used instead in the following. The geometry of the window is changed as specified and the window is restacked among siblings as described below, and a ConfigureNotify event is generated. If the width or height of the window has actually changed, then children of the window are affected as described below. Exposure processing is performed on formerly obscured windows. Changing the width or height of the window causes its contents to be moved or lost, depending on the bit-gravity of M.I.T. [Page 33] RFC 1013 June 1987 the window, and causes children to be reconfigured, depending on their win-gravity. For a change of width and height of W and H, we define the [x, y] pairs: NorthWest: [0, 0] North: [W/2, 0] NorthEast: [W, 0] West: [0, H/2] Center: [W/2, H/2] East: [W, H/2] SouthWest: [0, H] South: [W/2, H] SouthEast: [W, H] When a window with one of these bit-gravities is resized, the corresponding pair defines the change in position of each pixel in the window. When a window with one of these win-gravities has its parent window resized, the corresponding pair defines the change in position of the window within the parent. When a window is so repositioned, a GravityNotify event is generated. A gravity of Static indicates that the contents or origin should not move relative to the origin of the root window. If the change in size of the window is coupled with a change in position of [X, Y], then for bit-gravity the change in position of each pixel is [-X, -Y], and for win-gravity the change in position of a child when its parent is so resized is [-X, -Y]. Note that Static gravity still only takes effect when the width or height of the window is changed, not when the window is simply moved. A bit-gravity of Forget indicates that the window contents are always discarded after a size change; the window is tiled with its background (if no background is defined, the existing screen contents are not altered) and one or more exposure events are generated. A server may also ignore the specified bit-gravity and use Forget instead. A win-gravity of Unmap is like NorthWest, but the child is also unmapped when the parent is resized, and an UnmapNotify event is generated. If a sibling and a stack-mode is specified, the window is restacked as follows: Above: window is placed just above sibling Below: window is placed just below sibling TopIf: if sibling occludes window, then window is placed at the top of the stack BottomIf: if window occludes sibling, then window is M.I.T. [Page 34] RFC 1013 June 1987 placed at the bottom of the stack Opposite: if sibling occludes window, then window is placed at the top of the stack, else if window occludes sibling, then window is placed at the bottom of the stack If a stack-mode is specified but no sibling is specified, the window is restacked as follows: Above: window is placed at the top of the stack Below: window is placed at the bottom of the stack TopIf: if any sibling occludes window, then window is placed at the top of the stack BottomIf: if window occludes any sibling, then window is placed at the bottom of the stack Opposite: if any sibling occludes window, then window is placed at the top of the stack, else if window occludes any sibling, then window is placed at the bottom of the stack It is a Match error if a sibling is specified without a stack-mode, or if the window is not actually a sibling. Note that the computations for BottomIf, TopIf, and Opposite are performed with respect to the window's final geometry (as controlled by the other arguments to the request), not its initial geometry. CirculateWindow window: WINDOW direction: {RaiseLowest, LowerHighest} Errors: Window, Value If some other client has selected SubstructureRedirect on the window, then a CirculateRequest event is generated, and no further processing is performed. Otherwise, the following is performed, and then a CirculateNotify event is generated if the window is actually restacked. For RaiseLowest, raises the lowest mapped child (if any) that is occluded by another child to the top of the stack. For LowerHighest, lowers the highest mapped child (if any) that occludes another child to the bottom of the stack. Exposure processing is performed on formerly obscured windows. GetGeometry drawable: DRAWABLE => root: WINDOW depth: CARD8 M.I.T. [Page 35] RFC 1013 June 1987 x, y: INT16 width, height, border-width: CARD16 Errors: Drawable Returns the root and (current) geometry of the drawable. Depth is the number of bits per pixel for the object. X, y, and border-width will always be zero for pixmaps. For a window, the x and y coordinates specify the upper left outer corner of the window relative to its parent's origin, and the width and height specify the inside size (not including the border). It is legal to pass an InputOnly window as a drawable to this request. QueryTree window: WINDOW => root: WINDOW parent: WINDOW or None children: LISTofWINDOW Errors: Window Returns the root, the parent, and children of the window. The children are listed in bottom-to-top stacking order. InternAtom name: STRING8 only-if-exists: BOOL => atom: ATOM or None Errors: Value, Alloc Returns the atom for the given name. If only-if-exists is False, then the atom is created if it does not exist. The string should use the ASCII encoding, and upper/lower case matters. The lifetime of an atom is not tied to the interning client. Atoms remained defined until server reset (see Section 11). GetAtomName atom: ATOM => name: STRING8 Errors: Atom M.I.T. [Page 36] RFC 1013 June 1987 Returns the name for the given atom. ChangeProperty window: WINDOW property, type: ATOM format: {8, 16, 32} mode: {Replace, Prepend, Append} data: LISTofINT8 or LISTofINT16 or LISTofINT32 Errors: Window, Atom, Value, Match, Alloc Alters the property for the specified window. The type is uninterpreted by the server. The format specifies whether the data should be viewed as a list of 8-bit, 16-bit, or 32-bit quantities, so that the server can correctly byte-swap as necessary. If mode is Replace, the previous property value is discarded. If the mode is Prepend or Append, then the type and format must match the existing property value (else a Match error); if the property is undefined, it is treated as defined with the correct type and format with zero-length data. For Prepend, the data is tacked on to the beginning of the existing data, and for Append it is tacked on to the end of the existing data. Generates a PropertyNotify event on the window. The lifetime of a property is not tied to the storing client. Properties remain until explicitly deleted, or the window is destroyed, or until server reset (see Section 11). The maximum size of a property is server dependent. DeleteProperty window: WINDOW property: ATOM Errors: Window, Atom Deletes the property from the specified window if the property exists. Generates a PropertyNotify event on the window unless the property does not exist. GetProperty window: WINDOW property: ATOM type: ATOM or AnyPropertyType long-offset, long-length: CARD32 delete: BOOL => M.I.T. [Page 37] RFC 1013 June 1987 type: ATOM format: {8, 16, 32} bytes-after: CARD32 value: LISTofINT8 or LISTofINT16 or LISTofINT32 Errors: Window, Atom, Property, Match, Value If the specified property does not exist for the specifed window, a Property error is generated. Otherwise, if type AnyPropertyType is specified, (part of) the property is returned regardless of its type; if a type is specified, (part of) the property is returned only if its type equals the specified type (else a Match error). The actual type and format of the property are returned. Define the following values: N = actual length of the stored property in bytes (even if the format is 16 or 32) I = 4 * long-offset T = N - I L = MINIMUM(T, 4 * long-length) A = N - (I + L) The returned value starts at byte index I in the property (indexing from 0), and its length in bytes is L. It is a Value error if long-offset is given such that L is negative. The value of bytes-after is A, giving the number of trailing unread bytes in the stored property. If delete is True and bytes-after is zero, the property is also deleted from the window and a PropertyNotify event is generated on the window. RotateProperties window: WINDOW delta: INT8 properties: LISTofATOM Errors: Window, Atom, Match If the property names in the list are viewed as being numbered starting from zero, and there are N property names in the list, then the value associated with property name I becomes the value associated with property name (I + delta) mod N, for all I from zero to N - 1. The effect is to rotate the states by delta places around the virtual ring of property names (right for positive delta, left for negative delta). A PropertyNotify event is generated for each property, in the order listed. M.I.T. [Page 38] RFC 1013 June 1987 If an atom occurs more than once in the list or no property with that name is defined for the window, a Match error is generated. If an Atom or Match error is generated, no properties are changed. ListProperties window: WINDOW => atoms: LISTofATOM Errors: Window Returns the atoms of properties currently defined on the window. SetSelectionOwner selection: ATOM owner: WINDOW or None time: TIMESTAMP or CurrentTime Error: Atom, Window Changes the owner and last-change time of the specifed selection. The request has no effect if the specified time is earlier than the current last-change time of the specified selection or is later than the current server time; otherwise, the last-change time is set to the specified time, with CurrentTime replaced by the current server time. If the new owner is not the same as the current owner of the selection, and the current owner is a window, then the current owner is sent a SelectClear event. If the owner of a selection is a window, and the window is later destroyed, the owner of the selection automatically reverts to None, but the last-change time is not affected. The selection atom is uninterpreted by the server. Selections are global to the server. GetSelectionOwner selection: ATOM => owner: WINDOW or None Errors: Atom Returns the current owner of the specified selection, if any. ConvertSelection selection, target: ATOM M.I.T. [Page 39] RFC 1013 June 1987 property: ATOM or None requestor: WINDOW time: TIMESTAMP or CurrentTime Error: Atom, Window If the specified selection is owned by a window, the server sends a SelectionRequest event to the owner. If no owner for the specified selection exists, the server generates a SelectionNotify event to the requestor with property None. The arguments are passed on unchanged in either event. SendEvent destination: WINDOW or PointerWindow or InputFocus propagate: BOOL event-mask: SETofEVENT event: <normal-event-format> Errors: Window, Value If PointerWindow is specified, destination is replaced with the window that the pointer is in. If InputFocus is specified, then if the focus window contains the pointer, destination is replaced with the window that the pointer is in, and otherwise destination is replaced with the focus window. If propagate is False, then the event is sent to every client selecting on destination any of the event types in event-mask. If propagate is True and no clients have selected on destination any of the event types in event-mask, then destination is replaced with the closest ancestor of destination for which some client has selected a type in event-mask and no intervening window has that type in its do-not-propagate-mask. If no such window exists, or if the window is an ancestor of the focus window and InputFocus was originally specified sent to any clients. Otherwise, the event is reported to every client selecting on the final destination any of the types specified in event-mask. The event code must be one of the core events, or one of the events defined by an extension, so that the server can correctly byte swap the contents as necessary. The contents of the event are otherwise unaltered and unchecked by the server except to force on the most significant bit of the event code. M.I.T. [Page 40] RFC 1013 June 1987 Active grabs are ignored for this request. GrabPointer grab-window: WINDOW owner-events: BOOL event-mask: SETofPOINTEREVENT pointer-mode, keyboard-mode: {Synchronous, Asynchronous} confine-to: WINDOW or None cursor: CURSOR or None time: TIMESTAMP or CurrentTime => status: {Success, AlreadyGrabbed, Frozen, InvalidTime, NotViewable} Errors: Cursor, Window, Value Actively grabs control of the pointer. Further pointer events are only reported to the grabbing client. The request overrides any active pointer grab by this client. Event-mask is always augmented to include ButtonPress and ButtonRelease. If owner-events is False, all generated pointer events are reported with respect to grab-window, and are only reported if selected by event-mask. If owner-events is True, then if a generated pointer event would normally be reported to this client, it is reported normally; otherwise the event is reported with respect to the grab-window, and is only reported if selected by event-mask. For either value of owner-events, unreported events are simply discarded. Pointer-mode controls further processing of pointer events, and keyboard-mode controls further processing of keyboard events. If the mode is Asynchronous, event processing continues normally; if the device is currently frozen by this client, then processing of events for the device is resumed. If the mode is Synchronous, the device (as seen via the protocol) appears to freeze, and no further events for that device are generated by the server until the grabbing client issues a releasing AllowEvents request. Actual device changes are not lost while the device is frozen; they are simply queued for later processing. If a cursor is specified, then it is displayed regardless of what window the pointer is in. If no cursor is specified, then when the pointer is in grab-window or one of its subwindows, the normal cursor for that window is displayed, and otherwise the cursor for grab-window is displayed. M.I.T. [Page 41] RFC 1013 June 1987 If a confine-to window is specified, then the pointer will be restricted to stay contained in that window. The confine-to window need have no relationship to the grab-window. If the pointer is not initially in the confine-to window, then it is warped automatically to the closest edge (and enter/leave events generated normally) just before the grab activates. If the confine-to window is subsequently reconfigured, the pointer will be warped automatically as necessary to keep it contained in the window. This request generates EnterNotify and LeaveNotify events. The request fails with status AlreadyGrabbed if the pointer is actively grabbed by some other client. The request fails with status Frozen if the pointer is frozen by an active grab of another client. The request fails with status NotViewable if grab-window or confine-to window is not viewable. The request fails with status InvalidTime if the specified time is earlier than the last-pointer-grab time or later than the current server time; otherwise the last-pointer-grab time is set to the specified time, with CurrentTime replaced by the current server time. UngrabPointer time: TIMESTAMP or CurrentTime Releases the pointer if this client has it actively grabbed (from either GrabPointer or GrabButton or from a normal button press), and releases any queued events. The request has no effect if the specified time is earlier than the last-pointer-grab time or is later than the current server time. This request generates EnterNotify and LeaveNotify events. An UngrabPointer is performed automatically if the event window or confine-to window for an active pointer grab becomes not viewable. GrabButton modifiers: SETofKEYMASK or AnyModifier button: BUTTON or AnyButton grab-window: WINDOW owner-events: BOOL event-mask: SETofPOINTEREVENT pointer-mode, keyboard-mode: {Synchronous, Asynchronous} confine-to: WINDOW or None cursor: CURSOR or None M.I.T. [Page 42] RFC 1013 June 1987 Errors: Cursor, Window, Value, Access This request establishes a passive grab. In the future, if the specified button is pressed when the specified modifier keys are down (and no other buttons or modifier keys are down), and grab-window contains the pointer, and the confine-to window (if any) is viewable, and these constraints are not satisfied for any ancestor, then the pointer is actively grabbed as described in GrabPointer, the last-pointer-grab time is set to the time at which the button was pressed (as transmitted in the ButtonPress event), and the ButtonPress event is reported. The interpretation of the remaining arguments is as for GrabPointer. The active grab is terminated automatically when all buttons are released (independent of the state of modifier keys). A modifiers of AnyModifier is equivalent to issuing the request for all possible modifier combinations. A button of AnyButton is equivalent to issuing the request for all possible buttons. An Access error is generated if some other client has already issued a GrabButton with the same button/key combination on the same window. When using AnyModifier or AnyButton, the request fails completely (no grabs are established) if there is a combination. The request has no effect on an active grab. UngrabButton modifiers: SETofKEYMASK or AnyModifier button: BUTTON or AnyButton grab-window: WINDOW Errors: Window Releases the passive button/key combination on the specified window if it was grabbed by this client. A modifiers of AnyModifier is equivalent to issuing the request for all possible modifier combinations. A button of AnyButton is equivalent to issuing the request for all possible buttons. Has no effect on an active grab. ChangeActivePointerGrab event-mask: SETofPOINTEREVENT cursor: CURSOR or None time: TIMESTAMP or CurrentTime Errors: Cursor M.I.T. [Page 43] RFC 1013 June 1987 Changes the specified dynamic parameters if the pointer is actively grabbed by the client and the specified time is no earlier than the last-pointer-grab time and no later than the current server time. The interpretation of event-mask and cursor are as in GrabPointer. The event-mask is always augmented to include ButtonPress and ButtonRelease. Has no effect on the passive parameters of a GrabButton. GrabKeyboard grab-window: WINDOW owner-events: BOOL pointer-mode, keyboard-mode: {Synchronous, Asynchronous} time: TIMESTAMP or CurrentTime => status: {Success, AlreadyGrabbed, Frozen, InvalidTime, NotViewable} Errors: Window, Value Actively grabs control of the keyboard. Further key events are reported only to the grabbing client. The request overrides any active keyboard grab by this client. If owner-events is False, all generated key events are reported with respect to grab-window. If owner-events is True, then if a generated key event would normally be reported to this client, it is reported normally; otherwise the event is reported with respect to the grab-window. Both KeyPress and KeyRelease events are always reported, independent of any event selection made by the client. Pointer-mode controls further processing of pointer events, and keyboard-mode controls further processing of keyboard events. If the mode is Asynchronous, event processing continues normally; if the device is currently frozen by this client, then processing of events for the device is resumed. If the mode is Synchronous, the device (as seen via the protocol) appears to freeze, and no further events for that device are generated by the server until the grabbing client issues a releasing AllowEvents request. Actual device changes are not lost while the device is frozen; they are simply queued for later processing. This request generates FocusIn and FocusOut events. The request fails with status AlreadyGrabbed if the keyboard is actively grabbed by some other client. The M.I.T. [Page 44] RFC 1013 June 1987 request fails with status Frozen if the keyboard is frozen by an active grab of another client. The request fails with status NotViewable if grab-window is not viewable. The request fails with status InvalidTime if the specified time is earlier than the last-keyboard-grab time or later than the current server time; otherwise the last-keyboard-grab time is set to the specified time, with CurrentTime replaced by the current server time. UngrabKeyboard time: TIMESTAMP or CurrentTime Releases the keyboard if this client has it actively grabbed (from either GrabKeyboard or GrabKey), and releases any queued events. The request has no effect if the specified time is earlier than the last-keyboard-grab time or is later than the current server time. This request generates FocusIn and FocusOut events. An UngrabKeyboard is performed automatically if the event window for an active keyboard grab becomes not viewable. GrabKey key: KEYCODE or AnyNonModifier modifiers: SETofKEYMASK or AnyModifier grab-window: WINDOW owner-events: BOOL pointer-mode, keyboard-mode: {Synchronous, Asynchronous} Errors: Window, Value, Access This request establishes a passive grab on the keyboard. In the future, if the specified key (which can itself be a modifier key) is pressed when the specified modifier keys are down (and no other modifier keys are down), and the KeyPress event would be generated in grab-window or one of its inferiors, and these constraints are not satisfied for any ancestor, then the keyboard is actively grabbed as described in GrabKeyboard, the last-keyboard-grab time is transmitted in set to the time at which the key was pressed (as in the KeyPress event), and the KeyPress event is reported. The interpretation of the remaining arguments is as for GrabKeyboard. The active grab is terminated automatically when the specified key has been released (independent of the state of the modifier keys). A modifiers of AnyModifier is equivalent to issuing the request for all possible modifier combinations. A key of AnyNonModifier is equivalent to issuing the request for M.I.T. [Page 45] RFC 1013 June 1987 all possible non-modifier key codes. An Access error is generated if some other client has issued a GrabKey with the same key combination on the same window. When using AnyModifier or AnyNonModifier, the request fails completely (no grabs are established) if there is a conflicting grab for any combination. UngrabKey key: KEYCODE or AnyNonModifier modifiers: SETofKEYMASK or AnyModifier grab-window: WINDOW Errors: Window Releases the key combination on the specified window if it was grabbed by this client. A modifiers of AnyModifier is equivalent to issuing the request for all possible modifier combinations. A key of AnyNonModifier is equivalent to issuing the request for all possible non-modifier key codes. Has no effect on an active grab. AllowEvents mode: {AsyncPointer, SyncPointer, ReplayPointer, AsyncKeyboard, SyncKeyboard, ReplayKeyboard} time: TIMESTAMP or CurrentTime Errors: Value Releases some queued events if the client has caused a device to freeze. The request has no effect if the specified time is earlier than the last-grab time of the most recent active grab for the client, or if the specified time is later than the current server time. For AsyncPointer, if the pointer is frozen by the client, pointer event processing continues normally. If the pointer is frozen twice by the client on behalf of two separate grabs, AsyncPointer "thaws" for both. AsyncPointer has no effect if the pointer is not frozen by the client, but the pointer need not be grabbed by the client. For SyncPointer, if the pointer is frozen and actively grabbed by the client, pointer event processing continues normally until the next ButtonPress or ButtonRelease event is reported to the client, at which time the pointer again appears to freeze. However if the reported event causes the pointer grab to be released, then the pointer does not freeze. SyncPointer has no effect if the pointer is not frozen by the client, or if the pointer is not grabbed by M.I.T. [Page 46] RFC 1013 June 1987 the client. For ReplayPointer, if the pointer is actively grabbed by the client and is frozen as the result of an event having been sent to the client (either from the activation of a GrabButton, or from a previous AllowEvents with mode SyncPointer, but not from a GrabPointer), then the pointer grab is released and that event is completely reprocessed, but this time ignoring any passive grabs at or above (towards the root) the grab-window of the grab just released. The request has no effect if the pointer is not grabbed by the client, or if the pointer is not frozen as the result of an event. For AsyncKeyboard, if the keyboard is frozen by the client, keyboard event processing continues normally. If the pointer is frozen twice by the client on behalf of two separate grabs, AsyncPointer "thaws" for both. AsyncKeyboard has no effect if the keyboard is not frozen by the client, but the keyboard need not be grabbed by the client. For SyncKeyboard, if the keyboard is frozen and actively grabbed by the client, keyboard event processing continues normally until the next KeyPress or KeyRelease event is reported to the client, at which time the keyboard again appears to freeze. However if the reported event causes the keyboard grab to be released, then the keyboard does not freeze. SyncKeyboard has no effect if the keyboard is not frozen by the client, or if the keyboard is not grabbed by the client. For ReplayKeyboard, if the keyboard is actively grabbed by the client and is frozen as the result of an event having been sent to the client (either from the activation of a GrabKey, or from a previous AllowEvents with mode SyncKeyboard, but not from a GrabKeyboard), then the keyboard grab is released and that event is completely reprocessed, but this time ignoring any passive grabs at or above (towards the root) the grab-window of the grab just released. The request has no effect if the keyboard is not grabbed by the client, or if the keyboard is notfrozen as the result of an event. AsyncPointer, SyncPointer, and Replay Pointer have no effect on processing of keyboard events. AsyncKeyboard, SyncKeyboard, and ReplayKeyboard have no effect on processing of pointer events. It is possible for both a pointer grab and a keyboard grab to be active simultaneously (by the same or different M.I.T. [Page 47] RFC 1013 June 1987 clients). If a device is frozen on behalf of either grab, no event processing is performed for the device. It is possible for a single device to be frozen due to both grabs. In this case, the freeze must be released on behalf of both grabs before events can again be processed. GrabServer Disables processing of requests and close-downs on all other connections (than the one this request arrived on). UngrabServer Restarts processing of requests and close-downs on other connections. QueryPointer window: WINDOW => root: WINDOW child: WINDOW or None same-screen: BOOL root-x, root-y, win-x, win-y: INT16 mask: SETofKEYBUTMASK Errors: Window The root window the pointer is currently on, and pointer coordinates relative to the root's origin, are returned. If same-screen is False, then the pointer is not on the same screen as the argument window, and child is None and win-x and win-y are zero. If same-screen is True, then win-x and win-y are the pointer coordinates relative to the argument window's origin, and child is the child containing the pointer, if any. The current state of the modifier keys and the buttons are also returned. GetMotionEvents start, stop: TIMESTAMP or CurrentTime window: WINDOW => events: LISTofTIMECOORD where TIMECOORD: {x, y: CARD16 time: TIMESTAMP} Error: Window Returns all events in the motion history buffer that fall between the specified start and stop times (inclusive) and that have coordinates that lie within (including M.I.T. [Page 48] RFC 1013 June 1987 borders) the specified window at its present placement. The x and y coordinates are reported relative to the origin of the window. TranslateCoordinates src-window, dst-window: WINDOW src-x, src-y: INT16 => same-screen: BOOL child: WINDOW or None dst-x, dst-y: INT16 Errors: Window The src-x and src-y coordinates are taken relative to src-window's origin, and returned as dst-x and dst-y coordinates relative to dst-window's origin. If same-screen is False, then src-window and dst-window are on different screens, and dst-x and dst-y are zero. If the coordinates are contained in a mapped child of dst-window, then that child is returned. WarpPointer src-window: WINDOW or None dst-window: WINDOW src-x, src-y: INT16 src-width, src-height: CARD16 dst-x, dst-y: INT16 Errors: Window Moves the pointer to [dst-x, dst-y] relative to dst-window's origin. If src-window is None, the move is independent of the current pointer position, but if a window is specified, the move only takes place if the pointer is currently contained in a visible portion of the specified rectangle of the src-window. The src-x and src-y coordinates are relative to src-window's origin. If src-height is zero, it is replaced with the current height of src-window minus src-y. If src-width is zero, it is replaced with the current width of src-window minus src-x. This request cannot be used to move the pointer outside the confine-to window of an active pointer grab; an attempt will only move the pointer as far as the closest edge of the confine-to window. M.I.T. [Page 49] RFC 1013 June 1987 SetInputFocus focus: WINDOW or PointerRoot or None revert-to: {Parent, PointerRoot, None} time: TIMESTAMP or CurrentTime Errors: Window, Value Changes the input focus and the last-focus-change time. The request has no effect if the specified time is earlier than the current last-focus-change time or is later than the current server time; otherwise, the last-focus-change time is set to the specified time, with CurrentTime replaced by the current server time. If None is specified as the focus, all keyboard events are discarded until a new focus window is set. In this case, therevert-to argument is ignored. If a window is specified as the focus, it becomes the keyboard's focus window. If a generated keyboard event would normally be reported to this window or one of its inferiors, the event is reported normally; otherwise, the event is reported with respect to the focus window. If PointerRoot is specified as the focus, the focus window is dynamically taken to be the root window of whatever screen the pointer is on at each keyboard event. In this case, the revert-to argument is ignored. This request generates FocusIn and FocusOut events. If the focus window becomes not viewable, the new focus window depends on the revert-to argument. If revert-to is Parent, the focus reverts to the parent (or the closest viewable ancestor) and the new revert-to value is take to be None. If revert-to is PointerRoot or None, the focus reverts to that value. When the focus reverts, FocusIn and FocusOut events are generated, but the last-focus-change time is not affecte