I have found a source code demo of smooth animation.
Basically it use bitblt to do copy , and , xor operation
on background and src bitmaps.
BitBlt picSave.hdc, 0, 0, 60, 60, picDest.hdc, cx, cy, vbSrcCopy ' save bkgrnd
BitBlt picDest.hdc, cx, cy, 60, 60, picMask.hdc, 0, 0,
vbSrcAnd ' and mask
BitBlt picDest.hdc, cx, cy, 60, 60, picSrc.hdc, 0, 0,
vbSrcInvert ' xor source
The src and mask bitmap looks right to me. But when I
run the program , the supposed moving image ( a coin) is
messed with other colors. Seems and , xor opertion not
right. Is there any suggestion?