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