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XShm(3)                                          X FUNCTIONS                                         XShm(3)



NAME
       XShmQueryExtension, XShmQueryVersion, XShmPixmapFormat, XShmAttach, XShmDetach XShmCreateImage, XShm-PutImage, XShmPutImage,
       PutImage, 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);

       Status XShmPixmapFormat(
            Display *display);

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

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


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

       Status 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);

       Status 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 dis-play. display.
       play.

       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  ``Bad-Match'' ``BadMatch''
       Match'' 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



X Version 11                                    libXext 1.0.5                                        XShm(3)