XGetImage
Syntax
This function specifically supports rudimentary screen dumps.
XImage *XGetImage(display, d, x, y, width, height, plane_mask, format)
Display *display;
Drawable d;
int x, y;
unsigned int width, height;
unsigned long plane_mask;
int format;
Arguments
| display
| Specifies the connection to the X server.
|
| d
| Specifies the drawable.
|
x
y
| Specify the x and y coordinates, which are relative to the origin of the drawable and define the upper-left corner of the rectangle.
|
width
height
| Specify the width and height of the subimage, which define the dimensions of the rectangle.
|
| plane_mask
| Specifies the plane mask.
|
| format
| Specifies the format for the image.
You can pass
XYPixmap
or
ZPixmap .
|
Description
The
XGetImage()
function returns a pointer to an
XImage
structure.
This structure provides you with the contents of the specified rectangle of
the drawable in the format you specify.
If the format argument is
XYPixmap ,
the image contains only the bit planes you passed to the plane_mask argument.
If the plane_mask argument only requests a subset of the planes of the
display, the depth of the returned image will be the number of planes
requested.
If the format argument is
ZPixmap ,
XGetImage()
returns as zero the bits in all planes not
specified in the plane_mask argument.
The function performs no range checking on the values in plane_mask and ignores
extraneous bits.
XGetImage()
returns the depth of the image to the depth member of the
XImage
structure.
The depth of the image is as specified when the drawable was created,
except when getting a subset of the planes in
XYPixmap
format, when the depth is given by the number of bits set to 1 in plane_mask.
If the drawable is a pixmap,
the given rectangle must be wholly contained within the pixmap,
or a
BadMatch
error results.
If the drawable is a window,
the window must be viewable,
and it must be the case that if there were no inferiors or overlapping windows,
the specified rectangle of the window would be fully visible on the screen
and wholly contained within the outside edges of the window,
or a
BadMatch
error results.
Note that the borders of the window can be included and read with
this request.
If the window has backing-store, the backing-store contents are
returned for regions of the window that are obscured by noninferior
windows.
If the window does not have backing-store,
the returned contents of such obscured regions are undefined.
The returned contents of visible regions of inferiors
of a different depth than the specified window's depth are also undefined.
The pointer cursor image is not included in the returned contents.
If a problem occurs,
XGetImage()
returns NULL.
XGetImage()
can generate
BadDrawable ,
BadMatch ,
and
BadValue
errors.
Diagnostics
| BadDrawable
| A value for a Drawable argument does not name a
defined Window or Pixmap.
|
| BadMatch
| An
InputOnly
window is used as a Drawable.
|
| BadMatch
| Some argument or pair of arguments has the correct type and range but fails
to match in some other way required by the request.
|
| BadValue
| Some numeric value falls outside the range of values accepted by the request.
Unless a specific range is specified for an argument, the full range defined
by the argument's type is accepted. Any argument defined as a set of
alternatives can generate this error.
|
See also
XAddPixel(),
XCreateImage(),
XDestroyImage(),
XGetPixel(),
XInitImage(),
XPutImage(),
XPutPixel(),
XGetSubImage(),
"
Transferring Images between Client and Server".
Christophe Tronche, [email protected]
