用Api,
CombineRgn
CreateEllipticRgn
CreateEllipticRgnIndirect
CreatePolygonRgn
CreatePolyPolygonRgn
CreateRectRgn
CreateRectRgnIndirect
CreateRoundRectRgn
EqualRgn
ExtCreateRegion
FillRgn
FrameRgn
GetPolyFillMode
GetRegionData
GetRgnBox
InvertRgn
OffsetRgn
PaintRgn
PtInRegion
RectInRegion
SetPolyFillMode
例子:我的代码。
with FCanvas do
....
if RoundConner then
begin
Rgn:=CreateRoundRectRgn(left, Top, Left+Width, Top+Height,
FRoundMargin, FRoundMargin);
selectObject(handle, Rgn);
SaveDc(handle);
end;
....