NAME
XPutImage, XGetImage, XGetSubImage - transfer images
SYNTAX
int XPutImage(Display *display, Drawable d, GC gc, XImage *image, int
src_x, int src_y, int dest_x, int dest_y, unsigned int width,
unsigned int height);
XImage *XGetImage(Display *display, Drawable d, int x, int y, unsigned
int width, unsigned int height, unsigned long plane_mask, int
format);
XImage *XGetSubImage(Display *display, Drawable d, int x, int y,
unsigned int width, unsigned int height, unsigned long
plane_mask, int format, XImage *dest_image, int dest_x, dest_y);
ARGUMENTS
d Specifies the drawable.
dest_image
Specifies the destination image.
dest_x
dest_y Specify the x and y coordinates, which are relative to the
origin of the drawable and are the coordinates of the
subimage or which are relative to the origin of the
destination rectangle, specify its upper-left corner, and
determine where the subimage is placed in the destination
image.
display Specifies the connection to the X server.
format Specifies the format for the image. You can pass XYPixmap or
ZPixmap.
gc Specifies the GC.
image Specifies the image you want combined with the rectangle.
plane_mask
Specifies the plane mask.
src_x Specifies the offset in X from the left edge of the image
defined by the XImage structure.
src_y Specifies the offset in Y from the top edge of the image
defined by the XImage structure.
width
height Specify the width and height of the subimage, which define
the dimensions of the rectangle.
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.
DESCRIPTION
The XPutImage function combines an image with a rectangle of the
specified drawable. The section of the image defined by the src_x,
src_y, width, and height arguments is drawn on the specified part of
the drawable. If XYBitmap format is used, the depth of the image 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 of the image must match the depth of the drawable, or a
BadMatch error results.
If the characteristics of the image (for example, byte_order and
bitmap_unit) differ from what the server requires, XPutImage
automatically makes the appropriate conversions.
This function uses these GC components: function, plane-mask,
subwindow-mode, clip-x-origin, clip-y-origin, and clip-mask. It also
uses these GC mode-dependent components: foreground and background.
XPutImage can generate BadDrawable, BadGC, BadMatch, and BadValue
errors.
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.
The XGetSubImage function updates dest_image with the specified
subimage in the same manner as XGetImage. If the format argument is
XYPixmap, the image contains only the bit planes you passed to the
plane_mask argument. If the format argument is ZPixmap, XGetSubImage
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. As a convenience, XGetSubImage
returns a pointer to the same XImage structure specified by dest_image.
The depth of the destination XImage structure must be the same as that
of the drawable. If the specified subimage does not fit at the
specified location on the destination image, the right and bottom edges
are clipped. 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. If the window has backing-store, then 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. If a
problem occurs, XGetSubImage returns NULL.
XGetSubImage can generate BadDrawable, BadGC, BadMatch, and BadValue
errors.
DIAGNOSTICS
BadDrawable
A value for a Drawable argument does not name a defined
Window or Pixmap.
BadGC A value for a GContext argument does not name a defined
GContext.
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
Xlib - C Language X Interface