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NAME

       XShmQueryExtension,   XShmQueryVersion,  XShmPixmapFormat,  XShmAttach,
       XShmDetach      XShmCreateImage,      XShmPutImage,       XShmGetImage,
       XShmCreatePixmap,   XShmGetEventBase   -   X  Shared  Memory  extension
       functions

SYNTAX

       #include <X11/Xlib.h>
       #include <sys/ipc.h>
       #include <sys/shm.h>
       #include <X11/extensions/XShm.h>

       Bool XShmQueryExtension(
            Display *display);

       Bool XShmQueryVersion(
            Display *display;
            int *major, *minor;
            Bool *pixmaps);

       int XShmPixmapFormat(
            Display *display);

       Bool XShmAttach(
            Display *display;
            XShmSegmentInfo *shminfo);

       Bool XShmDetach(
            Display *display;
            XShmSegmentInfo *shminfo);

       XImage *XShmCreateImage (
            Display *display;
            Visual *visual;
            unsigned int depth;
            int format;
            char *data;
            XShmSegmentInfo *shminfo;
            unsigned int width, height);

       Bool XShmPutImage(
            Display *display;
            Drawable d;
            GC gc;
            XImage *image;
            int src_x, src_y, dest_x, dest_y;
            unsigned int width, height;
            bool send_event);

       Bool XShmGetImage (
            Display *display;
            Drawable d;
            XImage *image;
            int x, y;
            unsigned long plane_mask);

       Pixmap XShmCreatePixmap(
               Display *display;
               Drawable d;
               char *data;
            XShmSegmentInfo *shminfo;
            unsigned int width, height, depth);

       Status XShmGetEventBase(
            Display *display);

STRUCTURES

       Events:
       typedef struct {
           int type;               /* of event */
           unsigned long serial;   /* # of last request processed by server*/
           Bool send_event;        /* true if this came from a SendEvent request*/
           Display *display;       /* Display the event was read from */
           Drawable drawable;      /* drawable of request */
           int major_code;         /* ShmReqCode */
           int minor_code;         /* X_ShmPutImage */
           ShmSeg shmseg;          /* the ShmSeg used in the request*/
           unsigned long offset;   /* the offset into ShmSeg used in the request*/
       } XShmCompletionEvent;

       a structure of type XShmSegmentInfo :

       typedef struct {
           ShmSeg shmseg;      /* resource id */
           int shmid;          /* kernel id */
           char *shmaddr;      /* address in client */
           Bool readOnly;      /* how the server should attach it */
       } XShmSegmentInfo;

DESCRIPTION

       XShmQueryExtension checks to see if the shared  memory  extensions  are
       available for the specified display.

       XShmQueryVersion   returns   the   version  numbers  of  the  extension
       implementation. Shared memory pixmaps  are  supported  if  the  pixmaps
       argument returns true.

       XShmAttach tells the server to attach to your shared memory segment. If
       all goes well, you will get a non-zero status, back and your XImage  is
       ready for use.

       XShmDetach tells the server to detach from your shared memory segment.

       XShmPutImage  combines an image in memory with a shape of the specified
       drawable. If XYBitmap format is used, the  depth  must  be  one,  or  a
       ``BadMatch''  error results. The foreground pixel in the GC defines the
       source for the one bits in the image, and the background pixel  defines
       the  source for the zero bits. For XYPixmap and ZPixmap, the depth must
       match the depth of the drawable, or a ``BadMatch'' error results.

       XShmGetImage reads image data into a shared memory XImage where display
       is  the  display of interest, drawable is the source drawable, image is
       the destination XImage, x and y are offsets within  the  drawable,  and
       plane_mask defines which planes are to be read.

       XShmCreateImage allocates the memory needed for an XImage structure for
       the specified display but does not allocate space for the image itself.

       XShmPixmapFormat gets the format for the server.  If  your  application
       can  deal  with  the server pixmap data format, a shared memory segment
       and shminfo structure are created.

       XShmCreatePixmap points to a pixmap which you can manipulate in all  of
       the usual ways, with the added bonus of being able to edit its contents
       directly through the shared memory segment.

       XShmGetEventBase gets the completion event value.

SEE ALSO

       MIT-SHM - The MIT Shared Memory Extension



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