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