再学 GDI+[23] TGPLinearGradientBrush - 之二

 

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ComCtrls, StdCtrls, TeCanvas;

type
  TForm1 = class(TForm)
    ButtonColor1: TButtonColor;
    ButtonColor2: TButtonColor;
    TrackBar1: TTrackBar;
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure ButtonColor1Click(Sender: TObject);
    procedure ButtonColor2Click(Sender: TObject);
    procedure TrackBar1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
uses
  GDIPAPI,GDIPOBJ;
procedure TForm1.ButtonColor1Click(Sender: TObject);
begin
  Repaint;
end;

procedure TForm1.ButtonColor2Click(Sender: TObject);
begin
  Repaint;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ButtonColor1.Caption:='ɫ1     ';
  ButtonColor2.Caption:='ɫ2     ';
  ButtonColor1.SymbolColor:=clYellow;
  ButtonColor2.SymbolColor:=clRed;
  TrackBar1.ShowSelRange:=False;
  TrackBar1.Min:=0;
  TrackBar1.Max:=360;
end;

procedure TForm1.FormPaint(Sender: TObject);
var
  g:TGPGraphics;
  rt:TGPRect;
  lb:TGPLinearGradientBrush;
  c1,c2:TGPColor;
begin
  DoubleBuffered:=True;
  g:=TGPGraphics.Create(Canvas.Handle);
  rt:=MakeRect(60,40,ClientWidth - 120,ClientHeight - 50);
  c1:=ColorRefToARGB(ButtonColor1.SymbolColor);
  c2:=ColorRefToARGB(ButtonColor2.SymbolColor);
  lb:=TGPLinearGradientBrush.Create(rt,c1,c2,TrackBar1.Position);

  g.FillEllipse(lb,rt);

  lb.Free;
  g.Free;
end;

procedure TForm1.TrackBar1Change(Sender: TObject);
begin
  Repaint;
end;

end.