Delphi GDI+学习记录(21): 颜色

//颜色透明度var
　g: TGPGraphics;
　sb: TGPSolidBrush;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　sb := TGPSolidBrush.Create(MakeColor(128,255,0,0)); {128表示半透明}
　g.FillRectangle(sb,10,10,100,100);
　sb.Free;
　g.Free;
end;

//使用 GDI+ 的颜色类型var
　g: TGPGraphics;
　sb: TGPSolidBrush;
　color: TGPColor; {其实颜色是 DWORD 类型的}
begin
　g := TGPGraphics.Create(Canvas.Handle);
　color := aclRed;
　sb := TGPSolidBrush.Create(color);
　g.FillRectangle(sb,10,10,100,100);
　sb.Free;
　g.Free;
end;

//颜色混合模式var
　g: TGPGraphics;
　p: TGPPen;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(MakeColor(128,255,0,0),20);
　g.SetCompositingMode(CompositingModeSourceCopy); {改写背景色}
　g.DrawLine(p,11,11,111,111);
　g.SetCompositingMode(CompositingModeSourceOver); {混合背景色, 默认值}
　g.DrawLine(p,66,11,222,128);
　p.Free;
　g.Free;
end;

颜色混合模式: