X11 NONRECTANGULAR WINDOW SHAPE EXTENSION Version 1.0 MIT X Consortium Standard X Version 11, Release 5 Keith Packard X Consortium Laboratory for Computer Science Massachusetts Institute of Technology c Copyright 1989 by the Massachusetts Institute of Technol- ogy Permission to use, copy, modify, and distribute this docu- mentation for any purpose and without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. MIT makes no representations about the suitability for any purpose of the information in this document. This documentation is provided ``as is'' without express or implied warranty. 1. Overview This extension provides arbitrary window and border shapes within the X11 protocol. The restriction of rectangular windows within the X protocol is a significant limitation in the implementation of many styles of user interface. For example, many transient win- dows would like to display a ``drop shadow'' to give the illusion of 3 dimensions. As another example, some user interface style guides call for buttons with rounded corners; the full simulation of a nonrectangular shape, par- ticularly with respect to event distribution and cursor shape, is not possible within the core X protocol. As a final example, round clocks and nonrectangular icons are desirable visual addition to the desktop. This extension provides mechanisms for changing the visible shape of a window to an arbitrary, possibly disjoint, non- rectangular form. The intent of the extension is to supple- ment the existing semantics, not replace them. In particu- lar, it is desirable for clients which are unaware of the extension to still be able to cope reasonably with shaped windows. For example, window managers should still be able to negotiate screen real-estate in rectangular pieces. Toward this end, any shape specified for a window is clipped by the bounding rectangle for the window as specified by the window's geometry in the core protocol. An expected conven- tion would be that client programs expand their shape to fill the area offered by the window manager. 2. Description Each window (even with no shapes specified) is defined by two regions: the bounding region and the clip region. The bounding region is the area of the parent window which the window will occupy (including border). The clip region is the subset of the bounding region which is available for sub-windows and graphics. The area between the bounding region and the clip region is defined to be the border of the window. A non-shaped window will have a bounding region which is a rectangle spanning the window including its border; the clip region will be a rectangle filling the inside dimensions (not including the border). In this document, these areas are referred to as the default bounding region and the default clip region. For a window with inside size of width by height and border width bwidth, the default bounding and clip regions are the rectangles (relative to the window ori- gin): bounding.x = -bwidth bounding.y = -bwidth 1 X11 Nonrectangular Window Shape Extension bounding.width = width + 2 * bwidth bounding.height = height + 2 * bwidth clip.x = 0 clip.y = 0 clip.width = width clip.height = height This extension allows a client to modify either or both of the bounding or clip regions by specifying new regions which combine with the default regions. These new regions are called the client bounding region and the client clip region. They are specified relative to the origin of the window, and are always defined by offsets relative to the window origin (that is, region adjustments are not required when the window is moved). Three mechanisms for specifying regions are provided: a list of rectangles, a bitmap, and an existing bounding or clip region from a window. This is modeled on the specification of regions in graphics contexts in the core protocol, and allows a variety of different uses of the extension. When using an existing window shape as an operand in speci- fying a new shape, the client region is used, unless none has been set in which case the default region is used instead. The effective bounding region of a window is defined to be the intersection of the client bounding region with the default bounding region. Any portion of the client bounding region which is not included in the default bounding region will not be included in the effective bounding region on the screen. This means that window managers (or other geometry managers) used to dealing with rectangular client windows will be able to constrain the client to a rectangular area of the screen. Construction of the effective bounding region is dynamic; the client bounding region is not mutated to obtain the effective bounding region. If a client bounding region is specified which extends beyond the current default bounding region, and the window is later enlarged, the effective bounding region will be enlarged to include more of the client bounding region. The effective clip region of a window is defined to be the intersection of the client clip region with both the default clip region and the client bounding region. Any portion of the client clip region which is not included in both the default clip region and the client bounding region will not be included in the effective clip region on the screen. Construction of the effective clip region is dynamic; the client clip region is not mutated to obtain the effective 2 X11 Nonrectangular Window Shape Extension clip region. If a client clip region is specified which extends beyond the current default clip region, and the win- dow or its bounding region is later enlarged, the effective clip region will be enlarged to include more of the client clip region if it is included in the effective bounding region. The border of a window is defined to be the difference between the effective bounding region and the effective clip region. If this region is empty, no border is displayed. If this region is non-empty, the border is filled using the border-tile or border-pixel of the window as specified in the core protocol. Note that a window with a nonzero border width will never be able to draw beyond the default clip region of the window. Also note that a zero border width does not prevent a window from having a border, since the clip shape can still be made smaller than the bounding shape. All output to the window, and visible regions of any subwin- dows, will be clipped to the effective clip region. The server must not retain window contents beyond the effective bounding region with backing store. The window's origin (for graphics operations, background tiling, and subwindow placement) is not affected by the existence of a bounding region or clip region. Areas which are inside the default bounding region but out- side the effective bounding region are not part of the win- dow; these areas of the screen will be occupied by other windows. Input events which occur within the default bound- ing region but outside the effective bounding region will be delivered as if the window was not occluding the event posi- tion. Events which occur in a nonrectangular border of a window will be delivered to that window, just as for events which occur in a normal rectangular border. An InputOnly window can have its bounding region set, but it is a error to attempt to set a clip region on an InputOnly window, or to specify its clip region as a source to a request in this extension. The server must accept changes to the clip region of a root window, but the server is permitted to ignore requested changes to the bounding region of a root window. If the server accepts bounding region changes, the contents of the screen outside the bounding region are implementation depen- dent. 3. Types The following types are used in the request and event defin- itions in subsequent sections. 3 X11 Nonrectangular Window Shape Extension SHAPE_KIND: SHAPE_OP: means that the region specified as an explicit source in the request is stored unaltered as the new destination client region. means that the source and destination regions are unioned together to produce the new destination client region. means that the source and destination regions are intersected together to produce the new destination client region. means that the source region is subtracted from the destination region to produce the new destination region. means that the destination region is subtracted from the source region to produce the new destination region. 4. Requests => majorVersion: CARD16 minorVersion: CARD16 This request can be used to ensure that the server ver- sion of the SHAPE extension is usable by the client. This document defines major version one (1), minor ver- sion zero (0). dest: WINDOW destKind: SHAPE_KIND op: SHAPE_OP xOff, yOff: INT16 rectangles: LISTofRECTANGLES ordering: {UnSorted, YSorted, YXSorted, YXBanded} Errors: This request specifies an array of rectangles, relative to the origin of the window plus the specified offset (xOff and yOff) which together define a region. This region is combined (as specified by the operator op) with the existing client region (specified by destKind) of the destination window, and the result is stored as the specified client region of the destination window. Note that the list of rectangles can be empty, specify- ing an empty region; this is not the same as passing to If known by the client, ordering relations on the rec- tangles can be specified with the ordering argument. This may provide faster operation by the server. The meanings of the ordering values are the same as in the core protocol request. If an incorrect ordering is specified, the server may generate a error, but it is 4 X11 Nonrectangular Window Shape Extension not required to do so. If no error is generated, the graphics results are undefined. Except for the rectan- gles should be nonintersecting, or the resulting region will be undefined. means that the rectangles are in arbitrary order. means that the rectangles are nonde- creasing in their Y origin. additionally constrains order in that all rectangles with an equal Y origin are nondecreasing in their X origin. additionally con- strains by requiring that, for every possible Y scan- line, all rectangles that include that scanline have identical Y origins and Y extents. dest: WINDOW destKind: SHAPE_KIND op: SHAPE_OP xOff, yOff: INT16 source: PIXMAP or None Errors: The source in this request is a 1-bit deep pixmap, or If source is the specified client region is removed from the window causing the effective region to revert to the default region. The ShapeNotify event generated by this request and subsequent ShapeQueryExtents will report that a client shape has not been specified. If a valid pixmap is specified, it is converted to a region, with bits set to one included in the region and bits set to zero excluded, and an offset from the win- dow origin as specified by xOff and yOff. The result- ing region is then combined (as specified by the opera- tor op) with the existing client region (indicated by destKind) of the destination window, and the result is stored as the specified client region of the destina- tion window. The source pixmap and destination window must have been created on the same screen or else a error results. dest: WINDOW destKind: SHAPE_KIND op: SHAPE_OP xOff, yOff: INT16 source: WINDOW sourceKind: SHAPE_KIND Errors: The client region, indicated by sourceKind, of the source window is offset from the window origin by xOff and yOff and combined with the client region, indicated by destKind, of the destination window. The result is stored as the specified client region of the 5 X11 Nonrectangular Window Shape Extension destination window. The source and destination windows must be on the same screen or else a error results. dest: WINDOW destKind: SHAPE_KIND xOff, yOff: INT16 Errors: The client region, indicated by destKind, is moved relative to its current position by the amounts xOff and yOff. dest: WINDOW => boundingShaped: BOOL clipShaped: BOOL xBoundingShape: INT16 yBoundingShape: INT16 widthBoundingShape: CARD16 heightBoundingShape: CARD16 xClipShape: INT16 yClipShape: INT16 widthClipShape: CARD16 heightClipShape: CARD16 Errors: The boundingShaped and clipShaped results are if the corresponding client regions have been specified, else they are The x, y, width, and height values define the extents of the client regions, when a client region has not been specified, the extents of the corresponding default region are reported. window: WINDOW enable: BOOL Errors: Specifying enable as causes the server to send the requesting client a event whenever the bounding or clip region of the specified window is altered by any client. Specifying enable as causes the server to stop sending such events. window: WINDOW 6 X11 Nonrectangular Window Shape Extension => enable: BOOL Errors: If enable is then events for the window are generated for this client. window: WINDOW kind: SHAPE_KIND => rectangles: LISTofRECTANGLE ordering: {UnSorted, YSorted, YXSorted, YXBanded} Errors: A list of rectangles describing the region indicated by kind, and the ordering of those rectangles, is returned. The meaning of the ordering values is the same as in the request. 5. Events window: WINDOW kind: SHAPE_KIND shaped: BOOL x, y: INT16 width, height: CARD16 time: TIMESTAMP Whenever the client bounding or clip shape of a window is modified, a event is sent to each client which has used to request it. kind indicates which client region (bounding or clip) has been modified. shaped is when the window has a client shape of type kind, and is when the window no longer has a client shape of this type. x, y, width and height indicate the extents of the current shape. When shaped is these will indicate the extents of the default region. The timestamp indicates the server time when the shape was changed. 6. Encoding Please refer to the X11 Protocol Encoding document as this document uses conventions established there. The name of this extension is ``SHAPE''. 7 X11 Nonrectangular Window Shape Extension New types SHAPE_KIND 0 Bounding 1 Clip SHAPE_OP 0 Set 1 Union 2 Intersect 3 Subtract 4 Invert Requests 1 CARD8 opcode 1 0 shape opcode 2 1 request length => 1 1 Reply 1 unused 2 CARD16 sequence number 4 0 length 2 CARD16 major version 2 CARD16 minor version 20 unused 1 CARD8 opcode 1 1 shape opcode 2 4+2n request length 1 SHAPE_OP operation 1 SHAPE_KIND destination kind 1 ordering 0 UnSorted 1 YSorted 2 YXSorted 3 YXBanded 1 unused 4 WINDOW destination window 2 INT16 x offset 2 INT16 y offset 8n LISTofRECTANGLE rectangles 1 CARD8 opcode 1 2 shape opcode 2 5 request length 1 SHAPE_OP operation 1 SHAPE_KIND destination kind 2 unused 4 WINDOW destination window 2 INT16 x offset 2 INT16 y offset 4 PIXMAP source bitmap 0 None 1 CARD8 opcode 1 3 shape opcode 2 5 request length 1 SHAPE_OP operation 1 SHAPE_KIND destination kind 1 SHAPE_KIND source kind 1 unused 4 WINDOW destination window 2 INT16 x offset 2 INT16 y 8 X11 Nonrectangular Window Shape Extension offset 4 WINDOW source window 1 CARD8 opcode 1 4 shape opcode 2 4 request length 1 SHAPE_KIND destination kind 3 unused 4 WINDOW destination window 2 INT16 x offset 2 INT16 y offset 1 CARD8 opcode 1 5 shape opcode 2 2 request length 4 WINDOW destination window => 1 1 Reply 1 unused 2 CARD16 sequence number 4 0 reply length 1 BOOL bounding shaped 1 BOOL clip shaped 2 unused 2 INT16 bounding shape extents x 2 INT16 bounding shape extents y 2 CARD16 bounding shape extents width 2 CARD16 bounding shape extents height 2 INT16 clip shape extents x 2 INT16 clip shape extents y 2 CARD16 clip shape extents width 2 CARD16 clip shape extents height 4 unused 1 CARD8 opcode 1 6 shape opcode 2 3 request length 4 WINDOW destination window 1 BOOL enable 3 unused 1 CARD8 opcode 1 6 shape opcode 2 2 request length 4 WINDOW destination window => 1 1 Reply 1 BOOL enabled 2 CARD16 sequence number 4 0 reply length 24 unused 1 CARD8 opcode 1 7 shape opcode 2 3 request length 4 WINDOW window 1 SHAPE_KIND source kind 9 X11 Nonrectangular Window Shape Extension 3 unused => 1 1 Reply 1 ordering 0 UnSorted 1 YSorted 2 YXSorted 3 YXBanded 2 CARD16 sequence number 4 2n reply length 4 CARD32 nrects 20 unused 8n LISTofRECTANGLE rectangles Events 1 CARD8 type (0 + extension event base) 1 SHAPE_KIND shape kind 2 CARD16 sequence number 4 WINDOW affected window 2 INT16 x value of extents 2 INT16 y value of extents 2 CARD16 width of extents 2 CARD16 height of extents 4 TIMESTAMP server time 1 BOOL shaped 11 unused 7. C language Binding The C routines provide direct access to the protocol and add no additional semantics. The include file for this extension is The defined shape kinds are and The defined region operations are and Bool XShapeQueryExtension (display, event_base, error_base) Display *display; int *event_base; /* RETURN */ int *error_base; /* RETURN */ Returns if the specified display supports the SHAPE extension else If the extension is supported, *event_base is set to the event number for events and *error_base would be set to the error number for the first error for this extension. As no errors are defined for this version of the extension, the value returned here is not defined (nor useful). Status XShapeQueryVersion (display, major_version, minor_version) Display *display; int *major_version, *minor_version; /* RETURN */ If the extension is supported, the major and minor ver- sion numbers of the extension supported by the display 10 X11 Nonrectangular Window Shape Extension are set and a non-zero value is returned. Otherwise the arguments are not set and 0 is returned. XShapeCombineRegion (display, dest, dest_kind, x_off, y_off, region, op) Display *display; Window dest; int dest_kind, op, x_off, y_off; REGION *region; Converts the specified region into a list of rectangles and calls XShapeCombineRectangles (display, dest, dest_kind, x_off, y_off, rectangles, n_rects, op, ordering) Display *display; Window dest; int dest_kind, n_rects, op, x_off, y_off, ordering; XRectangle *rectangles; If the extension is supported, performs a CombineRec- tangles operation, otherwise the request is ignored. XShapeCombineMask (display, dest, dest_kind, x_off, y_off, src, op) Display *display; Window dest; int dest_kind, op, x_off, y_off; Pixmap src; If the extension is supported, performs a CombineMask operation, otherwise the request is ignored. XShapeCombineShape (display, dest, dest_kind, x_off, y_off, src, src_kind, op) Display *display; Window dest, src; int dest_kind, src_kind, op, x_off, y_off; If the extension is supported, performs a CombineShape operation, otherwise the request is ignored. XShapeOffsetShape (display, dest, dest_kind, x_off, y_off) Display *display; Window dest; int dest_kind, x_off, y_off; If the extension is supported, performs an OffsetShape operation, otherwise the request is ignored. Status XShapeQueryExtents (display, window, bounding_shaped, x_bounding, y_bounding, w_bounding, h_bounding, clip_shaped, x_clip, y_clip, w_clip, h_clip) Display *display; 11 X11 Nonrectangular Window Shape Extension Window window; Bool *bounding_shaped, *clip_shaped; /* RETURN */ int *x_bounding, *y_bounding, *x_clip, *y_clip; /* RETURN */ unsigned int *w_bounding, *h_bounding, *w_clip, *h_clip; /* RETURN */ If the extension is supported, x_bounding, y_bounding, w_bounding, h_bounding are set to the extents of the bounding shape, and x_clip, y_clip, w_clip, h_clip are set to the extents of the clip shape. For unspecified client regions, the extents of the corresponding default region are used. If the extension is supported a non-zero value is returned, otherwise 0 is returned. XShapeSelectInput (display, window, mask) Display *display; Window window; unsigned long mask; To make this extension more compatible with other interfaces, although only one event type can be selected via the extension, this C interface provides a general mechanism similar to the standard Xlib binding for window events. A mask value has been defined, which is the only valid bit in mask which may be speci- fied. The structure for this event is defined as fol- lows: typedef struct { int type; /* of event */ unsigned long serial;/* # of last request processed by server */ Bool send_event; /* true if this came frome a SendEvent request */ Display *display; /* Display the event was read from */ Window window; /* window of event */ int kind; /* ShapeBounding or ShapeClip */ int x, y; /* extents of new region */ unsigned width, height; Time time; /* server timestamp when region changed */ Bool shaped; /* true if the region exists */ } XShapeEvent; unsigned long XShapeInputSelected (display, window) Display *display Window window; 12 X11 Nonrectangular Window Shape Extension This returns the current input mask for extension events on the specified window; the value returned if is selected for is otherwise it returns zero. If the extension is not supported, 0 is returned. XRectangle * XShapeGetRectangles (display, window, kind, count, ordering) Display *display; Window window; int kind; int *count; /* RETURN */ int *ordering; /* RETURN */ If the extension is not supported, NULL is returned. Otherwise, a list of rectangles describing the region specified by kind is returned. 8. Glossary bounding region The area of the parent window which this window will occupy. This area is divided into two parts: the border and the interior. clip region The interior of the window, as a subset of the bounding region. This region describes the area which will be painted with the window background when the window is cleared, will contain all graphics output to the win- dow, and will clip any subwindows. default bounding region The rectangular area, as described by the core protocol window size, which covers the interior of the window and its border. default clip region The rectangular area as described by the core protocol window size which covers the interior of the window and excludes the border. client bounding region The region associated with a window which is directly modified via this extension when specified by Shape- Bounding. This region is used in conjunction with the default bounding region to produce the effective bound- ing region. client clip region The region associated with a window which is directly modified via this extension when specified by 13 X11 Nonrectangular Window Shape Extension ShapeClip. This region is used in conjunction with the default clip region and the client bounding region to produce the effective clip region. effective bounding region The actual shape of the window on the screen, including border and interior (but excluding the effects of over- lapping windows). When a window has a client bounding region, the effective bounding region is the intersec- tion of the default bounding region and the client bounding region. Otherwise, the effective bounding region is the same as the default bounding region. effective clip region The actual shape of the interior of the window on the screen (excluding the effects of overlapping windows). When a window has a client clip region or a client bounding region, the effective clip region is the intersection of the default clip region, the client clip region (if any) and the client bounding region (if any). Otherwise, the effective clip region is the same as the default clip region. 14