PTRSHAPE Field - cb

cb (USHORT)

Length of the pointer buffer.

The length of the pointer buffer available for the pointer device driver to build a row-by-column image for each bit plane for the mode the display is currently running. This value is supplied by the application. If the value is too small, pointer draw places the true length of the image in this field and returns an error.

For all OS/2 system-supported modes, cb is specified in bytes and is equal to:

Mono and Text Modes

For text mode, height and width must be 1, so length is always 4.

    cb = (height in chars) * (width in chars) * 2 * 2
       = 1 * 1 * 2 * 2
       = 4

Graphics Mode
Width-in-pels must be a multiple of 8.

    cb = (height in pels) * (width in pels) * (bits per pel) * 2 / 8

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