VClearOverlay
Name
VClearOverlay - erases a 1-bit overlay image.
Synopsis
VClearOverlay(win, ovl, xloc, yloc, width, height)
Window win;
int ovl;
int xloc, yloc;
int width, height;
Description
VClearOverlay erases a 1-bit overlay image within a rectangle in the
image window or one of its subwindows.
Return Value
0 - work successfully.
6 - invalid window ID.
225 - no overlay created.
237 - the overlay is not on.
Parameters
win - the image window ID or one of its subwindows' ID.
xloc, yloc - specifies x and y coordinates of the upper left corner of the
rectangle, relative to the origin of the image window.
width, height - specifies the width and height in pixels of the overlay.
ovl - specifies the overlay number to be used to erase the 1-bit image.
Side Effects
Any other graphics in that overlay within that rectangle will also be
erased.
Entry Conditions
VTurnOnOverlay should be called first. If ovl, xloc, yloc, width, or height
is invalid, or VCreateColormap is not called earlier, or the overlay image to
be erased is totally out of the specified window boundary, VClearOverlay
prints an error message to the standard error stream, produces a core dump
file and exits from the current process.
Related Functions
VDisplayColorImage,
VDisplayGrayImage,
VDisplayOverlay,
VTurnOnOverlay,
VTurnOffOverlay.