再學 GDI+[23]: TGPLinearGradientBrush - 之二

TGPLinearGradIEntBrush.Create(
　rect: TGPRect;　　　　　　　　{變化范圍}
　color1, color2: TGPColor;　　 {起始色與終止色}
　angle: Single;　　　　　　　　{旋轉角度}
　isAngleScalable: BOOL = FALSE {是否受 TLinearGradIEntMode 的影響, 可選值, 默認不受影響}
);
TGPLinearGradIEntBrush.Create(
　rect: TGPRectF;
　color1, color2: TGPColor;
　angle: Single;
　isAngleScalable: BOOL = FALSE
);本例效果圖:

　　代碼文件: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.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 197
　ClIEntWidth = 253
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poScreenCenter
　OnCreate = FormCreate
　OnPaint = FormPaint
　PixelsPerInch = 96
　TextHeight = 13
　object ButtonColor1: TButtonColor
　　Left = 143
　　Top = 8
　　Width = 49
　　Caption = 'ButtonColor1'
　　TabOrder = 0
　　OnClick = ButtonColor1Click
　end
　object ButtonColor2: TButtonColor
　　Left = 198
　　Top = 8
　　Width = 49
　　Caption = 'ButtonColor2'
　　TabOrder = 1
　　OnClick = ButtonColor2Click
　end
　object TrackBar1: TTrackBar
　　Left = 1
　　Top = 9
　　Width = 137
　　Height = 24
　　TabOrder = 2
　　OnChange = TrackBar1Change
　end
end