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X11R7.4 - man page for xcreateimage (x11r4 section 3)

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XCreateImage(3) 			  XLIB FUNCTIONS			  XCreateImage(3)

NAME
       XInitImage, XCreateImage, XGetPixel, XPutPixel, XSubImage, XAddPixel, XDestroyImage -
       image utilities

SYNTAX
       Status XInitImage(XImage *image);

       XImage *XCreateImage(Display *display, Visual *visual, unsigned int depth, int format, int
	      offset, char *data, unsigned int width, unsigned int height, int bitmap_pad, int
	      bytes_per_line);

       unsigned long XGetPixel(XImage *ximage, int x, int y);

       int XPutPixel(XImage *ximage, int x, int y, unsigned long pixel);

       XImage *XSubImage(XImage *ximage, int x, int y, unsigned int subimage_width, unsigned int
	      subimage_height);

       int XAddPixel(XImage *ximage, long value);

       int XDestroyImage(XImage *ximage);

ARGUMENTS
       bitmap_pad
		 Specifies the quantum of a scanline (8, 16, or 32).  In other words, the start
		 of one scanline is separated in client memory from the start of the next scan-
		 line by an integer multiple of this many bits.

       bytes_per_line
		 Specifies the number of bytes in the client image between the start of one scan-
		 line and the start of the next.

       data	 Specifies the image data.

       depth	 Specifies the depth of the image.

       display	 Specifies the connection to the X server.

       format	 Specifies the format for the image.  You can pass XYBitmap, XYPixmap, or
		 ZPixmap.

       height	 Specifies the height of the image, in pixels.

       offset	 Specifies the number of pixels to ignore at the beginning of the scanline.

       pixel	 Specifies the new pixel value.

       subimage_height
		 Specifies the height of the new subimage, in pixels.

       subimage_width
		 Specifies the width of the new subimage, in pixels.

       value	 Specifies the constant value that is to be added.

       visual	 Specifies the Visual structure.

       width	 Specifies the width of the image, in pixels.

       ximage	 Specifies the image.

       x
       y	 Specify the x and y coordinates.

DESCRIPTION
       The XInitImage function initializes the internal image manipulation routines of an image
       structure, based on the values of the various structure members.  All fields other than
       the manipulation routines must already be initialized.  If the bytes_per_line member is
       zero, XInitImage will assume the image data is contiguous in memory and set the
       bytes_per_line member to an appropriate value based on the other members; otherwise, the
       value of bytes_per_line is not changed.	All of the manipulation routines are initialized
       to functions that other Xlib image manipulation functions need to operate on the type of
       image specified by the rest of the structure.

       This function must be called for any image constructed by the client before passing it to
       any other Xlib function.  Image structures created or returned by Xlib do not need to be
       initialized in this fashion.

       This function returns a nonzero status if initialization of the structure is successful.
       It returns zero if it detected some error or inconsistency in the structure, in which case
       the image is not changed.

       The XCreateImage function allocates the memory needed for an XImage structure for the
       specified display but does not allocate space for the image itself.  Rather, it initial-
       izes the structure byte-order, bit-order, and bitmap-unit values from the display and
       returns a pointer to the XImage structure.  The red, green, and blue mask values are
       defined for Z format images only and are derived from the Visual structure passed in.
       Other values also are passed in.  The offset permits the rapid displaying of the image
       without requiring each scanline to be shifted into position.  If you pass a zero value in
       bytes_per_line, Xlib assumes that the scanlines are contiguous in memory and calculates
       the value of bytes_per_line itself.

       Note that when the image is created using XCreateImage, XGetImage, or XSubImage, the
       destroy procedure that the XDestroyImage function calls frees both the image structure and
       the data pointed to by the image structure.

       The basic functions used to get a pixel, set a pixel, create a subimage, and add a con-
       stant value to an image are defined in the image object.  The functions in this section
       are really macro invocations of the functions in the image object and are defined in
       <X11/Xutil.h>.

       The XGetPixel function returns the specified pixel from the named image.  The pixel value
       is returned in normalized format (that is, the least significant byte of the long is the
       least significant byte of the pixel).  The image must contain the x and y coordinates.

       The XPutPixel function overwrites the pixel in the named image with the specified pixel
       value.  The input pixel value must be in normalized format (that is, the least significant
       byte of the long is the least significant byte of the pixel).  The image must contain the
       x and y coordinates.

       The XSubImage function creates a new image that is a subsection of an existing one.  It
       allocates the memory necessary for the new XImage structure and returns a pointer to the
       new image.  The data is copied from the source image, and the image must contain the rec-
       tangle defined by x, y, subimage_width, and subimage_height.

       The XAddPixel function adds a constant value to every pixel in an image.  It is useful
       when you have a base pixel value from allocating color resources and need to manipulate
       the image to that form.

       The XDestroyImage function deallocates the memory associated with the XImage structure.

SEE ALSO
       XPutImage(3X11)
       Xlib - C Language X Interface

X Version 11				   libX11 1.2.1 			  XCreateImage(3)
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