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


SYNTAX

       Status XInitImage(image)
             XImage *image;

       XImage *XCreateImage(display, visual, depth, format, off-
       set, data, width, height, bitmap_pad,
                               bytes_per_line)
             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, x, y)
             XImage *ximage;
             int x;
             int y;

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

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

       XAddPixel(ximage, value)
             XImage *ximage;
             long value;

       XDestroyImage(ximage)
               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

       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 pix-
                 els.

       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 initial-
       ized.  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 ini-
       tialized 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
       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 struc-
       ture and the data pointed to by the image structure.

       The basic functions used to get a pixel, set a pixel, cre-
       ate a subimage, and add a constant value to an image are
       defined in the image object.  The functions in this sec-
       tion 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 normal-
       ized 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 coordi-
       nates.

       The XSubImage function creates a new image that is a sub-
       section of an existing one.  It allocates the memory nec-
       essary 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 rectangle 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 associ-
       ated with the XImage structure.


SEE ALSO

       XPutImage(3X11)
       Xlib - C Language X Interface



X Version 11               Release 6.4                          1