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XCOMPOSITE(3) libXcomposite XCOMPOSITE(3) NAME Xcomposite - X Composite Extension library SYNOPSIS #include <X11/extensions/Xcomposite.h> Bool XCompositeQueryExtension(Display *dpy, int *event_base_return, int *error_base_return); Status XCompositeQueryVersion(Display *dpy, int *major_version_return, int *minor_version_return); int XCompositeVersion(void); void XCompositeRedirectWindow(Display *dpy, Window window, int update); void XCompositeRedirectSubwindows(Display *dpy, Window window, int update); void XCompositeUnredirectWindow(Display *dpy, Window window, int update); void XCompositeUnredirectSubwindows(Display *dpy, Window window, int update); XserverRegion XCompositeCreateRegionFromBorderClip(Display *dpy, Window window); Pixmap XCompositeNameWindowPixmap(Display *dpy, Window window); Window XCompositeGetOverlayWindow(Display *dpy, Window window); void XCompositeReleaseOverlayWindow(Display *dpy, Window window); DESCRIPTION The composite extension provides several related mechanisms: Per-hierarchy storage The rendering of an entire hierarchy of windows is redirected to off-screen storage. The pixels of that hierarchy are available whenever it is viewable. Storage is automatically reallocated when the top level window changes size. Contents beyond the geometry of the top window are not preserved. Automatic shadow update When a hierarchy is rendered off-screen, the X server provides an automatic mechanism for presenting those contents within the parent window. The implementation is free to make this update lag behind actual rendering operations by an unspecified amount of time. This automatic update mechanism may be disabled so that the parent window contents can be completely determined by an external application. Composite Overlay Window Version 0.3 of the protocol adds the Composite Overlay Window, which provides compositing managers with a surface on which to draw without interference. This window is always above normal windows access the XID of this window is via the CompositeGetOverlayWindow request. Initially, the Composite Overlay Window is unmapped. Parent window clipping Version 0.4 of the protocol modifies the semantics of parent window clipping in the presence of manual redirected children. With this version, the area in the parent covered by manual redirected children is left in the parent clip list instead of being removed as in older versions. Per-hierarchy storage may be created for individual windows or for all children of a window. Manual shadow update may be selected by only a single application for each window; manual update may also be selected on a per-window basis or for each child of a window. Detecting when to update may be done with the Damage extension. The off-screen storage includes the window contents, its borders and the contents of all descendants. ARGUMENTS display Pointer to the Display structure returned from XOpenDisplay for the connection to the X server. event_base_return Pointer to integer where the base value for Composite Extension events will be stored. error_base_return Pointer to integer where the base value for Composite Extension errors will be stored. major_version_return Pointer to integer where the major version of the Composite Extension supported by the X server will be stored. minor_version_return Pointer to integer where the minor version of the Composite Extension supported by the X server will be stored. window Specifies the window ID to operate on. update Specifies the mode for updating the window contents. Must be either CompositeRedirectAutomatic or CompositeRedirectManual. FUNCTIONS XCompositeQueryExtension XCompositeQueryExtension determines if the Composite Extension is available on the given display. It returns True if the extension is supported, otherwise False. If the extension is present, the base values for events and errors are returned, and can be used to decode incoming event and error values. XCompositeQueryVersion XCompositeQueryVersion determines if the X Server supports a client violates this rule, the effects of all subsequent XComposite calls that it makes are undefined. XCompositeVersion XCompositeVersion returns the version of the X Composite library. The version number is encoded as: (major * 10000) + (minor * 100) + revision For example, version 1.4.6 would be encoded as the integer 10406. XCompositeRedirectWindow XCompositeRedirectWindow requests the X server to direct the hierarchy starting at window to off-screen storage. The update argument specifies whether the contents are mirrored to the parent window automatically or not. Only one client at a time may specify an update type of CompositeRedirectManual, another attempt will result in a BadAccess error. When all clients enabling redirection terminate, the redirection will automatically be disabled. The root window may not be redirected. Doing so results in a BadMatch error. Specifying an invalid window id will result in a BadWindow error. XCompositeRedirectSubwindows XCompositeRedirectSubwindows requests the X server to redirect hierarchies starting at all current and future children of window as in XCompositeRedirectWindow. If update is CompositeRedirectManual, then painting of the window background during window manipulation and ClearArea requests is inhibited. XCompositeUnredirectWindow XCompositeUnredirectWindow requests the X server to terminate redirection of window. If the specified window was not selected for redirection by the current client, a BadValue error results. XCompositeUnredirectSubwindows XCompositeUnredirectWindow requests the X server to terminate redirection of all children of window. If the specified window was not selected for sub-redirection by the current client, a BadValue error results. XCompositeCreateRegionFromBorderClip XCompositeCreateRegionFromBorderClip creates a region containing the "usual" border clip value; that is the area of the window clipped against siblings and the parent. This region can be used to restrict rendering to suitable areas while updating only a single window. The region is copied at the moment the request is executed; future changes to the window hierarchy will not be reflected in this region. XCompositeNameWindowPixmap XCompositeNameWindowPixmap creates and returns a pixmap id that The X server must support at least version 0.2 of the Composite Extension for XCompositeNameWindowPixmap. XCompositeGetOverlayWindow XCompositeGetOverlayWindow returns the window ID of the Composite Overlay Window for the screen specified by the argument window. This function notifies the X server that the client wishes to use the Composite Overlay Window of this screen. If this Composite Overlay Window has not yet been mapped, it is mapped by this request. The Composite Overlay Window for a particular screen will be unmapped when all clients who have called this function have either called XCompositeReleaseOverlayWindow for that screen, or terminated their connection to the X server. The X server must support at least version 0.3 of the Composite Extension for XCompositeGetOverlayWindow. XCompositeReleaseOverlayWindow This request specifies that the client is no longer using the Composite Overlay Window on the screen specified by the argument window. A screen's Composite Overlay Window is unmapped when there are no longer any clients using it. The X server must support at least version 0.3 of the Composite Extension for XCompositeReleaseOverlayWindow. AUTHORS Keith Packard <keithp@keithp.com> Extension specification and implementation Deron Johnson <deron.johnson@sun.com> Overlay Window specification and implementation <pubdate>23 April 2007</pubdate> XCOMPOSITE(3)