XInitImage(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 subim-
              age_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 mem-
                 ory from the start of the next scanline by an integer multi-
                 ple of this many bits.

       bytes_per_line
                 Specifies the number of bytes in the client image between the
                 start of one scanline 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 spec-
       ified 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 struc-
       ture 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 initializes 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 subim-
       age, and add a constant 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 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 associated with the
       XImage structure.

XInitImage(3)

NAME

SYNTAX

ARGUMENTS

DESCRIPTION

SEE ALSO