SetWriteMask

Set the pixel write mask value for a RastPort (V39).

Set the current value of the bit write mask for the rastport. bits of the pixel with zeros in their mask will not be modified by subsequent drawing operations.

rp

a pointer to a valid RastPort structure.

msk

a longword mask value.

Graphics devices which do not support per-bit masking will return 0 (failure).

graphics/gfxmacros.h