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Converting XImage to PNG
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XPutImage(3) XLIB FUNCTIONS XPutImage(3) 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 for- mat); 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 rectan- gle. 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 back- ing-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 prob- lem 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 XYP- ixmap, 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 back- ing-store, the returned contents of such obscured regions are undefined. The returned contents of visible regions of inferiors of a dif- ferent 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 argu- ment, 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 X Version 11 libX11 1.2.1 XPutImage(3)
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