Delphi GDI+學習記錄(10): 線性漸變畫刷 - LinearGradientBrush

//線性漸變畫刷var
　g: TGPGraphics;
　lb: TGPLinearGradientBrush;
　rect: TGPRect;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　rect := MakeRect(11,11,222,111);
　lb := TGPLinearGradientBrush.Create(rect, aclBlue, aclGreen, LinearGradientModeHorizontal);
　g.FillEllipse(lb, rect);
　lb.Free;
　g.Free;
end;

//定義漸變的位置與顏色var
　g : TGPGraphics;
　p: TGPPen;
　lb: TGPLinearGradientBrush;
　p1,p2: TGPPoint;
　c1,c2: TGPColor;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p1 := MakePoint(0, 0);
　p2 := MakePoint(200, 100);
　c1 := MakeColor(255, 0, 0, 255);
　c2 := MakeColor(255, 0, 255, 0);
　lb := TGPLinearGradientBrush.Create(p1, p2, c1, c2);
　p:= TGPPen.Create(lb, 10);
　g.DrawLine(p, 0, 0, 600, 300);
　g.FillEllipse(lb, 10, 100, 200, 100);
　lb.Free;
　p.Free;
　g.Free;
end;

//自定義漸變過渡效果var
　g : TGPGraphics;
　lb: TGPLinearGradientBrush;
　p1,p2: TGPPoint;
　c1,c2: TGPColor;
const
　Factors: array[0..2] of Single = (0.0, 0.5, 1.0);　 {顏色比例}
　Positions: array[0..2] of Single = (0.0, 0.2, 1.0); {位置比例, 兩個數組元素須相同}
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p1 := MakePoint(0, 10);
　p2 := MakePoint(200, 10);
　c1 := aclBlack;
　c2 := aclRed;
　lb := TGPLinearGradientBrush.Create(p1, p2, c1, c2);
　lb.SetBlend(@Factors, @Positions, 3); {設置漸變因子}
　g.FillEllipse(lb, 0, 30, 200, 100);
　g.FillRectangle(lb, 0, 155, 500, 30);
　lb.Free;
　g.Free;
end;

線性漸變的方向參數:

Delphi 微軟 說明 LinearGradientModeBackwardDiagonal BackwardDiagonal 指定從右上到左下的漸變。 LinearGradientModeForwardDiagonal ForwardDiagonal 指定從左上到右下的漸變。 LinearGradientModeHorizontal Horizontal 指定從左到右的漸變。 LinearGradientModeVertical Vertical 指定從上到下的漸變。