NAME

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

SYNTAX

XImage *XCreateImage(display, visual, depth, format, offset,
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;

int 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;

int 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 the
               next scanline by an integer multiple of this many
               bits.

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     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 a pointer to the image data.

depth Specifies the depth of the image.

display Specifies the connection to the XWIN 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 a pointer to the visual.

width     Specifies the width of the image, in pixels.

ximage    Specifies a pointer to the image.

x
y         Specify the x and y coordinates.

DESCRIPTION

     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 struc-
     ture.  The red, green, and blue mask values are defined for
     Z format images only and are derived from the Visual struc-
     ture 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

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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 constant offset to a Z format 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 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 subsec-
tion 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.

SEE ALSO

     XPutImage(3X11)
     Xlib - C Language X Interface

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XWIN 3.0               Last change: 9/1/88                 .ie t