再学GDI+[23]: TGPLinearGradientBrush - 之二

再学GDI+[23]: TGPLinearGradientBrush - 之二2012-05-01 cnblogs 万一

TGPLinearGradientBrush.Create（
 rect: TGPRect;        {变化范围}
 color1, color2: TGPColor;   {起始色与终止色}
 angle: Single;        {旋转角度}
 isAngleScalable: BOOL = FALSE {是否受 TLinearGradientMode 的影响, 可选值, 默认不 受影响}
）;
TGPLinearGradientBrush.Create（
 rect: TGPRectF;
 color1, color2: TGPColor;
 angle: Single;
 isAngleScalable: BOOL = FALSE
）;

本例效果图:

代码文件:

unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, StdCtrls, TeCanvas, ExtCtrls, ComCtrls;
type
 TForm1 = class（TForm）
  ButtonColor1: TButtonColor;
  ButtonColor2: TButtonColor;
  TrackBar1: TTrackBar;
  procedure FormCreate（Sender: TObject）;
  procedure FormPaint（Sender: TObject）;
  procedure TrackBar1Change（Sender: TObject）;
  procedure ButtonColor1Click（Sender: TObject）;
  procedure ButtonColor2Click（Sender: TObject）;
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI, TypInfo;
procedure TForm1.FormCreate（Sender: TObject）;
begin
 ButtonColor1.Caption := "色1   ";
 ButtonColor2.Caption := "色2   ";
 ButtonColor1.SymbolColor := clLime;
 ButtonColor2.SymbolColor := clBlack;
 TrackBar1.ShowSelRange := False;
 TrackBar1.Min := 0;
 TrackBar1.Max := 360;
end;
procedure TForm1.FormPaint（Sender: TObject）;
var
 g: TGPGraphics;
 lb: TGPLinearGradientBrush;
 c1,c2: TGPColor;
 r: TGPRect;
begin
 g := TGPGraphics.Create（Canvas.Handle）;
 r := MakeRect（20, 40, ClientWidth - 40, ClientHeight - 50）;
 c1 := ColorRefToARGB（ButtonColor1.SymbolColor）;
 c2 := ColorRefToARGB（ButtonColor2.SymbolColor）;
 lb := TGPLinearGradientBrush.Create（r, c1, c2, TrackBar1.Position）;
 g.FillEllipse（lb, r）;
 lb.Free;
 g.Free;
end;
procedure TForm1.TrackBar1Change（Sender: TObject）;
begin
 Repaint;
end;
procedure TForm1.ButtonColor1Click（Sender: TObject）;
begin
 Repaint;
end;
procedure TForm1.ButtonColor2Click（Sender: TObject）;
begin
 Repaint;
end;
end.