再學 GDI+[79]: 區域(8) - Transform - 區域的 Matrix 變換

矩陣變換(Matrix)功能很強大, 這裡只是旋轉了一下.

　　本例效果圖:

　　代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls, ComCtrls;
type
　TForm1 = class(TForm)
　　TrackBar1: TTrackBar;
　　procedure FormPaint(Sender: TObject);
　　procedure FormCreate(Sender: TObject);
　　procedure TrackBar1Change(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　TrackBar1.Min := -45;
　TrackBar1.Max := 45;
　DoubleBuffered := True;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　b: TGPBrush;
　rgn: TGPRegion;
　Matrix: TGPMatrix;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　b := TGPHatchBrush.Create(HatchStyleMin, aclSilver, aclChocolate);
　rgn := TGPRegion.Create(MakeRect(40, 40, ClientWidth-80, ClIEntHeight-100));
　Matrix := TGPMatrix.Create;
　Matrix.Rotate(TrackBar1.Position);
　rgn.Transform(Matrix);
　g.FillRegion(b, rgn);
　Matrix.Free;
　rgn.Free;
　b.Free;
　g.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
　Repaint;
end;
end.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 174
　ClIEntWidth = 197
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poDesktopCenter
　OnCreate = FormCreate
　OnPaint = FormPaint
　PixelsPerInch = 96
　TextHeight = 13
　object TrackBar1: TTrackBar
　　Left = 0
　　Top = 151
　　Width = 193
　　Height = 23
　　ShowSelRange = False
　　TabOrder = 0
　　OnChange = TrackBar1Change
　end
end