GDI+ 学习记录(11): 路径渐变画刷 PathGradientBrush

//路径渐变画刷
var
  g: TGPGraphics;
  path: TGPGraphicsPath;
  pb: TGPPathGradientBrush; {声明渐变画刷}
  num: Integer;
const
  colors: array[0..0] of TGPColor = (aclAqua);
begin
  g := TGPGraphics.Create(Canvas.Handle);
  path := TGPGraphicsPath.Create;
  path.AddEllipse(0,0,166,88);

  pb := TGPPathGradientBrush.Create(path);   {建立渐变画刷}
  pb.SetCenterColor(MakeColor(255,0,0,255)); {中心颜色}

  num := 1;
  pb.SetSurroundColors(@colors, num); {周围的颜色}
  {第二个参数, 不能用常数代替; 它好像是第一个数组参数的索引+1}

  g.FillEllipse(pb, 0, 0, 166, 88); {需要和定义的渐变效果的大小一样}
  //g.FillPath(pb,path); {直接画路径效果也一样}

  path.Free;
  pb.Free;
  g.Free;
end;


//可以通过点数组的指针创建路径画刷
var
  g : TGPGraphics;
  pts: array[0..2] of TGPPoint;
  pb: TGPPathGradientBrush;
begin
  g := TGPGraphics.Create(Canvas.Handle);

  pts[0] := MakePoint(100, 0);
  pts[1] := MakePoint(200, 200);
  pts[2] := MakePoint(0, 200);

  pb:= TGPPathGradientBrush.Create(PGPPoint(@pts), 3);

  g.FillRectangle(pb, 0, 0, 200, 200);
  {没有指定中心颜色和周边颜色, 将分别默认黑色和白色}

  pb.Free;
  g.Free;
end;


//设置路径画刷的中心点
var
  g: TGPGraphics;
  path: TGPGraphicsPath;
  pb: TGPPathGradientBrush;
  num: Integer;
const
  colors : array[0..0] of TGPColor = (aclAqua);
begin
  g := TGPGraphics.Create(Canvas.Handle);
  path:= TGPGraphicsPath.Create;
  path.AddEllipse(0, 0, 140, 70);

  pb:= TGPPathGradientBrush.Create(path);

  pb.SetCenterPoint(MakePoint(120, 40)); {设置中心点}

  pb.SetCenterColor(MakeColor(255, 0, 0, 255));

  num := 1;
  pb.SetSurroundColors(@colors, num);

  g.FillEllipse(pb, 0, 0, 140, 70);

  path.Free;
  pb.Free;
  g.Free;
end;


//使用灰度校正
var
  g: TGPGraphics;
  path: TGPGraphicsPath;
  pb: TGPPathGradientBrush;
  num: Integer;
const
  colors: array[0..0] of TGPColor = (aclAqua);
begin
  g := TGPGraphics.Create(Canvas.Handle);
  path := TGPGraphicsPath.Create;
  path.AddEllipse(0,0,166,88);

  pb := TGPPathGradientBrush.Create(path);
  pb.SetGammaCorrection(True); {使用灰度校正}

  num := 1;
  pb.SetSurroundColors(@colors, num);

  g.FillEllipse(pb, 0, 0, 166, 88);

  path.Free;
  pb.Free;
  g.Free;
end;


//多种颜色及位置
var
  g : TGPGraphics;
  pts: array[0..2] of TGPPoint;
  pb: TGPPathGradientBrush;
const
  colors: array[0..2] of TGPColor = (aclGreen, aclAqua, aclBlue);
  pos: array[0..2] of Single = (0.0, 0.25, 1.0); {颜色位置需要 >0、<1, 是百分百}
begin
  g := TGPGraphics.Create(Canvas.Handle);

  pts[0] := MakePoint(100, 0);
  pts[1] := MakePoint(200, 200);
  pts[2] := MakePoint(0, 200);

  pb:= TGPPathGradientBrush.Create(PGPPoint(@pts), 3); {根据点数组指针建立路径画刷}

  pb.SetInterpolationColors(@colors, @pos, 3); {设置颜色位置}

  g.FillRectangle(pb, 0, 0, 200, 200);

  pb.Free;
  g.Free;
end;


//设置多种周边颜色
var
  g: TGPGraphics;
  path: TGPGraphicsPath;
  pb: TGPPathGradientBrush;
  colors: array[0..9] of TGPColor;
  num: Integer;
const
  pts : array[0..9] of TGPPoint =
    ((x:75 ; y:0  ), (x:100; y:50 ),
     (x:150; y:50 ), (x:112; y:75 ),
     (x:150; y:150), (x:75 ; y:100),
     (x:0  ; y:150), (x:37 ; y:75 ),
     (x:0  ; y:50 ), (x:50 ; y:50 ));
begin
  g := TGPGraphics.Create(Canvas.Handle);

  path:= TGPGraphicsPath.Create;
  path.AddLines(PGPPoint(@pts), 10);

  pb:= TGPPathGradientBrush.Create(path);

  pb.SetCenterColor(MakeColor(255, 255, 0, 0));

  colors[0] := MakeColor(255, 0, 0, 0);
  colors[1] := MakeColor(255, 0, 255, 0);
  colors[2] := MakeColor(255, 0, 0, 255);
  colors[3] := MakeColor(255, 255, 255, 255);
  colors[4] := MakeColor(255, 0, 0, 0);
  colors[5] := MakeColor(255, 0, 255, 0);
  colors[6] := MakeColor(255, 0, 0, 255);
  colors[7] := MakeColor(255, 255, 255, 255);
  colors[8] := MakeColor(255, 0, 0, 0);
  colors[9] := MakeColor(255, 0, 255, 0);

  num := 10;
  pb.SetSurroundColors(@colors, num); {设置多种周边颜色}

  g.FillPath(pb, path);

  pb.SetGammaCorrection(True); {使用灰度校正}
  g.TranslateTransform(200.0, 0.0);
  g.FillPath(pb, path);

  path.Free;
  pb.Free;
  g.Free;
end;


//描绘在不同的区域
var
  g : TGPGraphics;
  pb: TGPPathGradientBrush;
  p: TGPPen;
  colors: array[0..4] of TGPColor;
  num: Integer;
const
  pts: array[0..4] of TGPPointF =
   ((x: 0.0  ; y: 0.0),
    (x: 160.0; y: 0.0),
    (x: 160.0; y: 200.0),
    (x: 80.0 ; y: 150.0),
    (x: 0.0  ; y: 200.0));
begin
  g := TGPGraphics.Create(Canvas.Handle);

  pb:= TGPPathGradientBrush.Create(PGPPointF(@pts), 5);

  colors[0] := MakeColor(255, 255, 0, 0);
  colors[1] := MakeColor(255, 0, 255, 0);
  colors[2] := MakeColor(255, 0, 255, 0);
  colors[3] := MakeColor(255, 0, 0, 255);
  colors[4] := MakeColor(255, 255, 0, 0);

  num := 5;
  pb.SetSurroundColors(@colors, num);

  pb.SetCenterColor(MakeColor(255, 255, 255, 255));

  g.FillRectangle(pb, MakeRect(0, 0, 180, 220));

  p := TGPPen.Create(aclBlack);
  g.DrawRectangle(p, MakeRect(0, 0, 180, 220));

  p.Free;
  pb.Free;
  g.Free;
end;