再学 GDI+[79]: 区域(8) - Transform - 区域的 Matrix 变换

矩阵变换(Matrix)功能很强大, 这里只是旋转了一下.

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本例效果图:

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代码文件:

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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.


 
   

窗体文件:

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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