imgchanged(3Tk)

NAME
     Tk_ImageChanged - notify widgets that image needs to be redrawn

SYNOPSIS
     #include <tk.h>

     Tk_ImageChanged(imageMaster, x, y, width, height, imageWidth, imageHeight)

ARGUMENTS
     Tk_ImageMaster   imageMaster   (in)      Token for image, which was
                                              passed to image's createProc
                                              when the image was created.

     int              x             (in)      X-coordinate of upper-left
                                              corner of region that needs
                                              redisplay (measured from upper-
                                              left corner of image).

     int              y             (in)      Y-coordinate of upper-left
                                              corner of region that needs
                                              redisplay (measured from upper-
                                              left corner of image).

     int              width         (in)      Width of region that needs to be
                                              redrawn, in pixels.

     int              height        (in)      Height of region that needs to
                                              be redrawn, in pixels.

     int              imageWidth    (in)      Current width of image, in
                                              pixels.

     int              imageHeight   (in)      Current height of image, in
                                              pixels.


DESCRIPTION
     An image manager calls Tk_ImageChanged for an image whenever anything
     happens that requires the image to be redrawn.  As a result of calling
     Tk_ImageChanged, any widgets using the image are notified so that they
     can redisplay themselves appropriately.  The imageMaster argument
     identifies the image, and x, y, width, and height specify a rectangular
     region within the image that needs to be redrawn.  imageWidth and
     imageHeight specify the image's (new) size.

     An image manager should call Tk_ImageChanged during its createProc to
     specify the image's initial size and to force redisplay if there are
     existing instances for the image.  If any of the pixel values in the
     image should change later on, Tk_ImageChanged should be called again with
     x, y, width, and height values that cover all the pixels that changed.
     If the size of the image should change, then Tk_ImageChanged must be
     called to indicate the new size, even if no pixels need to be
     redisplayed.


SEE ALSO
     Tk_CreateImageType


KEYWORDS
     images, redisplay, image size changes