1XShm(3)                           X FUNCTIONS                          XShm(3)
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NAME

6       XShmQueryExtension,   XShmQueryVersion,  XShmPixmapFormat,  XShmAttach,
7       XShmDetach  XShmCreateImage,   XShmPutImage,   XShmGetImage,   XShmCre‐
8       atePixmap, XShmGetEventBase - X Shared Memory extension functions
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SYNTAX

11       #include <X11/Xlib.h>
12       #include <sys/ipc.h>
13       #include <sys/shm.h>
14       #include <X11/extensions/XShm.h>
15
16       Bool XShmQueryExtension(
17            Display *display);
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19       Bool XShmQueryVersion(
20            Display *display;
21            int *major, *minor;
22            Bool *pixmaps);
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24       int XShmPixmapFormat(
25            Display *display);
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27       Bool XShmAttach(
28            Display *display;
29            XShmSegmentInfo *shminfo);
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31       Bool XShmDetach(
32            Display *display;
33            XShmSegmentInfo *shminfo);
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36       XImage *XShmCreateImage (
37            Display *display;
38            Visual *visual;
39            unsigned int depth;
40            int format;
41            char *data;
42            XShmSegmentInfo *shminfo;
43            unsigned int width, height);
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45       Bool XShmPutImage(
46            Display *display;
47            Drawable d;
48            GC gc;
49            XImage *image;
50            int src_x, src_y, dest_x, dest_y;
51            unsigned int width, height;
52            bool send_event);
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54       Bool XShmGetImage (
55            Display *display;
56            Drawable d;
57            XImage *image;
58            int x, y;
59            unsigned long plane_mask);
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61       Pixmap XShmCreatePixmap(
62               Display *display;
63               Drawable d;
64               char *data;
65            XShmSegmentInfo *shminfo;
66            unsigned int width, height, depth);
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68       Status XShmGetEventBase(
69            Display *display);
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STRUCTURES

72       Events:
73       typedef struct {
74           int type;               /* of event */
75           unsigned long serial;   /* # of last request processed by server*/
76           Bool send_event;        /* true if this came from a SendEvent request*/
77           Display *display;       /* Display the event was read from */
78           Drawable drawable;      /* drawable of request */
79           int major_code;         /* ShmReqCode */
80           int minor_code;         /* X_ShmPutImage */
81           ShmSeg shmseg;          /* the ShmSeg used in the request*/
82           unsigned long offset;   /* the offset into ShmSeg used in the request*/
83       } XShmCompletionEvent;
84
85       a structure of type XShmSegmentInfo :
86
87       typedef struct {
88           ShmSeg shmseg;      /* resource id */
89           int shmid;          /* kernel id */
90           char *shmaddr;      /* address in client */
91           Bool readOnly;      /* how the server should attach it */
92       } XShmSegmentInfo;
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DESCRIPTION

96       XShmQueryExtension  checks  to  see if the shared memory extensions are
97       available for the specified display.
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99       XShmQueryVersion returns the version numbers of the extension implemen‐
100       tation.  Shared  memory  pixmaps  are supported if the pixmaps argument
101       returns true.
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103       XShmAttach tells the server to attach to your shared memory segment. If
104       all  goes well, you will get a non-zero status, back and your XImage is
105       ready for use.
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107       XShmDetach tells the server to detach from your shared memory segment.
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109       XShmPutImage combines an image in memory with a shape of the  specified
110       drawable.  If  XYBitmap  format  is  used,  the depth must be one, or a
111       ``BadMatch'' error results. The foreground pixel in the GC defines  the
112       source  for the one bits in the image, and the background pixel defines
113       the source for the zero bits. For XYPixmap and ZPixmap, the depth  must
114       match the depth of the drawable, or a ``BadMatch'' error results.
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116       XShmGetImage reads image data into a shared memory XImage where display
117       is the display of interest, drawable is the source drawable,  image  is
118       the  destination  XImage,  x and y are offsets within the drawable, and
119       plane_mask defines which planes are to be read.
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121       XShmCreateImage allocates the memory needed for an XImage structure for
122       the specified display but does not allocate space for the image itself.
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124       XShmPixmapFormat  gets  the  format for the server. If your application
125       can deal with the server pixmap data format, a  shared  memory  segment
126       and shminfo structure are created.
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128       XShmCreatePixmap  points to a pixmap which you can manipulate in all of
129       the usual ways, with the added bonus of being able to edit its contents
130       directly through the shared memory segment.
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132       XShmGetEventBase gets the completion event value.
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SEE ALSO

135       MIT-SHM - The MIT Shared Memory Extension
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139X Version 11                     libXext 1.3.4                         XShm(3)
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