To invert the pixels enclosed by a rectangle, use the InvertRect procedure. The rectangle whose enclosed pixels are to be inverted. The InvertRect procedure inverts the pixels enclosed by the rectangle that you specify in the r parameter.
Every white pixel becomes black and every black pixel becomes white.
The pen location does not change. The InvertRect procedure was designed for 1-bit images in basic graphics ports. This procedure operates on color pixels in color graphics ports, but the results are predictable only with direct pixels or 1-bit pixel maps. The eight colors used in basic QuickDraw are stored in a color table represented by the global variable QDColors . To display those eight basic QuickDraw colors on an indexed device, Color QuickDraw uses the Color Manager to obtain indexes to the colors in the CLUT that best map to the colors in the QDColors color table.