XCreateImage(XS)  X Version 11 (Release 5) 6 January 1993   XCreateImage(XS)


 Name

    XCreateImage - 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;

    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


    bitmappad       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.

    bytesperline   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 XYBit-
                     map, XYPixmap, or ZPixmap.

    height           Specifies the height of the image, in pixels.

    offset           Specifies the number of pixels to ignore at the begin-
                     ning of the scanline.

    pixel            Specifies the new pixel value.

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

    subimagewidth   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 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 dis-
    playing of the image without requiring each scanline to be shifted into
    position.  If you pass a zero value in bytesperline, Xlib assumes that
    the scanlines are contiguous in memory and calculates the value of
    bytesperline 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 value to an image are defined in the image object.
    The functions in this section are really macro invocations of the func-
    tions 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-sig-
    nificant 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 for-
    mat (that is, the least-significant byte of the long is the least-signif-
    icant byte of the pixel).  The image must contain the x and y coordi-
    nates.

    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, subimagewidth, and subimageheight.

    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(XS)
    Xlib - C Language X Interface