XShm(3)                    X FUNCTIONS                    XShm(3)



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

SYNTAX
       #include 
       #include 
       #include 
       #include 

       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, width, height;
            int format;
            char *data;
            XShmSegmentInfo *shminfo);

       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 display.

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

       XShmAttach  tells the server to attach to your shared mem-
       ory 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'' 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 manipu-
       late 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 1.0.4                   XShm(3)