--- name: "Xmbuf" section: "3" platform: "linux" package: "libxext" version: "1.3.7-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/Xmbuf" --- # Xmbuf(3) X multibuffering functions ## NAME XmbufQueryExtension, XmbufGetVersion, XmbufCreateBuffers, XmbufDestroyBuffers, XmbufDisplayBuffers, XmbufGetWindowAttributes, XmbufChangeWindowAttributes, XmbufGetBufferAttributes, XmbufChangeBufferAttributes, XmbufGetScreenInfo, XmbufCreateStereoWindow - X multibuffering functions ## SYNTAX ``` #include Bool XmbufQueryExtension( Display *dpy, int *event_base_return, int *error_base_return); Status XmbufGetVersion( Display *dpy, int *major_version_return, int *minor_version_return); int XmbufCreateBuffers( Display *dpy, Window window, int count, int update_action, int update_hint, Multibuffer *buffers_update); void XmbufDestroyBuffers( Display *dpy, Window window); void XmbufDisplayBuffers( Display *dpy, int count, Multibuffer *buffers, int min_delay, int max_delay); Status XmbufGetWindowAttributes( Display *dpy, Window window, XmbufWindowAttributes *attributes); void XmbufChangeWindowAttributes( Display *dpy, Window window, unsigned long valuemask, XmbufSetWindowAttributes *attributes); Status XmbufGetBufferAttributes( Display *dpy, Multibuffer buffer, XmbufBufferAttributes *attributes); void XmbufChangeBufferAttributes( Display *dpy, Multibuffer buffer, unsigned long valuemask, XmbufSetBufferAttributes *attributes); Status XmbufGetScreenInfo( Display *dpy, Drawable drawable, int *nmono_return, XmbufBufferInfo **mono_info_return, int *nstereo_return, XmbufBufferInfo **stereo_info_return); Window XmbufCreateStereoWindow( Display *dpy, Window parent, int x, int y, unsigned int width, unsigned int height, unsigned int border_width, int depth, unsigned int class, /* InputOutput, InputOnly*/ Visual *visual, unsigned long valuemask, XSetWindowAttributes *attributes, Multibuffer *left_return, Multibuffer *right_return); ``` ## STRUCTURES *Events:* ``` typedef struct { int type; /* of event */ unsigned long serial; /* # of last request processed by server */ int send_event; /* true if this came from a SendEvent request */ Display *display; /* Display the event was read from */ Multibuffer buffer; /* buffer of event */ int state; /* see Clobbered constants above */ } XmbufClobberNotifyEvent; typedef struct { int type; /* of event */ unsigned long serial; /* # of last request processed by server */ int send_event; /* true if this came from a SendEvent request */ Display *display; /* Display the event was read from */ Multibuffer buffer; /* buffer of event */ } XmbufUpdateNotifyEvent; ``` *Per-window attributes that can be got:* ``` typedef struct { int displayed_index; /* which buffer is being displayed */ int update_action; /* Undefined, Background, Untouched, Copied */ int update_hint; /* Frequent, Intermittent, Static */ int window_mode; /* Mono, Stereo */ int nbuffers; /* Number of buffers */ Multibuffer *buffers; /* Buffers */ } XmbufWindowAttributes; ``` *Per-window attributes that can be set:* ``` typedef struct { int update_hint; /* Frequent, Intermittent, Static */ } XmbufSetWindowAttributes; ``` *Per-buffer attributes that can be got:* ``` typedef struct { Window window; /* which window this belongs to */ unsigned long event_mask; /* events that have been selected */ int buffer_index; /* which buffer is this */ int side; /* Mono, Left, Right */ } XmbufBufferAttributes; ``` *Per-buffer attributes that can be set:* ``` typedef struct { unsigned long event_mask; /* events that have been selected */ } XmbufSetBufferAttributes; ``` *Per-screen buffer info (there will be lists of them):* ``` typedef struct { VisualID visualid; /* visual usable at this depth */ int max_buffers; /* most buffers for this visual */ int depth; /* depth of buffers to be created */ } XmbufBufferInfo; ``` ## DESCRIPTION The application programming library for the *X11 Double-Buffering, Multi-Buffering, and Stereo Extension* contains the interfaces described below. With the exception of **XmbufQueryExtension**, if any of these routines are called with a display that does not support the extension, the ExtensionErrorHandler (which can be set with **XSetExtensionErrorHandler** and functions the same way as **XSetErrorHandler**) will be called and the function will then return. **XmbufQueryExtension** returns **True** if the multibuffering/stereo extension is available on the given display. If the extension exists, the value of the first event code (which should be added to the event type constants **MultibufferClobberNotify** and **MultibufferUpdateNotify** to get the actual values) is stored into *event\_base\_return* and the value of the first error code (which should be added to the error type constant **MultibufferBadBuffer** to get the actual value) is stored into *error\_base\_return*. **XmbufGetVersion** gets the major and minor version numbers of the extension. The return value is zero if an error occurs or non-zero if no error happens. **XmbufCreateBuffers** requests that *count* buffers be created with the given *update\_action* and *update\_hint* and be associated with the indicated *window*. The number of buffers created is returned (zero if an error occurred) and *buffers\_update* is filled in with that many Multibuffer identifiers. **XmbufDestroyBuffers** destroys the buffers associated with the given *window*. **XmbufDisplayBuffers** displays the indicated buffers their appropriate windows within *max\_delay* milliseconds after *min\_delay* milliseconds have passed. No two buffers may be associated with the same window or else a Match error is generated. **XmbufGetWindowAttributes** gets the multibuffering attributes that apply to all buffers associated with the given *window*. The list of *attributes* returned may be freed with **XFree**. Returns non-zero on success and zero if an error occurs. **XmbufChangeWindowAttributes** sets the multibuffering attributes that apply to all buffers associated with the given window. This is currently limited to the *update\_hint*. **XmbufGetBufferAttributes** gets the attributes for the indicated buffer. Returns non-zero on success and zero if an error occurs. **XmbufChangeBufferAttributes** sets the *attributes* for the indicated *buffer*. This is currently limited to the *event\_mask*. **XmbufGetScreenInfo** gets the parameters controlling how mono and stereo windows may be created on the screen of the given *drawable*. The numbers of sets of visual and depths are returned in *nmono\_return* and *nstereo\_return*. If *nmono\_return* is greater than zero, then *mono\_info\_return* is set to the address of an array of **XmbufBufferInfo** structures describing the various visuals and depths that may be used. Otherwise, *mono\_info\_return* is set to NULL. Similarly, *stereo\_info\_return* is set according to *nstereo\_return*. The storage returned in *mono\_info\_return* and *stereo\_info\_return* may be released by **XFree**. If no errors are encountered, non-zero will be returned. **XmbufCreateStereoWindow** creates a stereo window in the same way that **XCreateWindow** creates a mono window. The buffer ids for the left and right buffers are returned in *left\_return* and *right\_return*, respectively. If an extension error handler that returns is installed, **None** will be returned if the extension is not available on this display. ## PREDEFINED VALUES Update\_action field: ``` MultibufferUpdateActionUndefined MultibufferUpdateActionBackground MultibufferUpdateActionUntouched MultibufferUpdateActionCopied ``` Update\_hint field: ``` MultibufferUpdateHintFrequent MultibufferUpdateHintIntermittent MultibufferUpdateHintStatic ``` Valuemask fields: ``` MultibufferWindowUpdateHint MultibufferBufferEventMask ``` Mono vs. stereo and left vs. right: ``` MultibufferModeMono MultibufferModeStereo MultibufferSideMono MultibufferSideLeft MultibufferSideRight ``` Clobber state: ``` MultibufferUnclobbered MultibufferPartiallyClobbered MultibufferFullyClobbered ``` Event stuff: ``` MultibufferClobberNotifyMask MultibufferUpdateNotifyMask MultibufferClobberNotify MultibufferUpdateNotify MultibufferNumberEvents MultibufferBadBuffer MultibufferNumberErrors ``` ## BUGS This manual page needs more work. ## SEE ALSO *Extending X for Double Buffering, Multi-Buffering, and Stereo*