GDI+ 学习记录(10) 线性渐变画刷 - LinearGradientBrush[转]

//线性渐变画刷

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;

//定义渐变的位置与颜色

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;

//自定义渐变过渡效果

var

  g : TGPGraphics;

  lb: TGPLinearGradientBrush;

  p1,p2: TGPPoint;

  c1,c2: TGPColor;

const

  Factors: array[0..2] of Single = (0.0, 0.5, 1.0);   {颜色比例}

  Positions: array[0..2] of Single = (0.0, 0.2, 1.0); {位置比例, 两个数组元素须相同}

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); {设置渐变因子}

 

  g.FillEllipse(lb, 0, 30, 200, 100);

  g.FillRectangle(lb, 0, 155, 500, 30);

 

  lb.Free;

  g.Free;

end;

 

线性渐变的方向参数:

Delphi	微软	说明
LinearGradientModeBackwardDiagonal	BackwardDiagonal	指定从右上到左下的渐变。
LinearGradientModeForwardDiagonal	ForwardDiagonal	指定从左上到右下的渐变。
LinearGradientModeHorizontal	Horizontal	指定从左到右的渐变。
LinearGradientModeVertical	Vertical	指定从上到下的渐变。