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 程式師世界 >> 編程語言 >> 更多編程語言 >> Delphi >> 再學GDI+[33]: TGPPen - 畫筆的幾何變換 - SetTransform

再學GDI+[33]: TGPPen - 畫筆的幾何變換 - SetTransform

編輯:Delphi

幾何變換也就是 Matrix 變換, 畫筆的 Matrix 會忽略 dx、dy 平移參數; 選擇 LineCapRound 線帽效果比較好.

本例效果圖:

代碼文件:unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, ComCtrls, StdCtrls, ExtCtrls;
type
 TForm1 = class(TForm)
  Panel1: TPanel;
  Button1: TButton;
  TrackBar1: TTrackBar;
  TrackBar2: TTrackBar;
  TrackBar3: TTrackBar;
  TrackBar4: TTrackBar;
  procedure FormCreate(Sender: TObject);
  procedure FormPaint(Sender: TObject);
  procedure TrackBar1Change(Sender: TObject);
  procedure TrackBar2Change(Sender: TObject);
  procedure TrackBar3Change(Sender: TObject);
  procedure TrackBar4Change(Sender: TObject);
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
const
 n = 40;
begin
 TrackBar1.Min := -n;
 TrackBar1.Max := n;
 TrackBar2.Min := -n;
 TrackBar2.Max := n;
 TrackBar3.Min := -n;
 TrackBar3.Max := n;
 TrackBar4.Min := -n;
 TrackBar4.Max := n;
 TrackBar1.Position := 10;
 TrackBar2.Position := 0;
 TrackBar3.Position := 0;
 TrackBar4.Position := 10;
 Button1.OnClick := FormCreate;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
 g: TGPGraphics;
 b: TGPBrush;
 p: TGPPen;
 matrix: TGPMatrix;
 m11, m12, m21, m22: Single;
begin
 g := TGPGraphics.Create(Canvas.Handle);
 b := TGPHatchBrush.Create(HatchStyleLargeGrid, aclForestGreen);
 p := TGPPen.Create(b, 16);
 m11 := TrackBar1.Position / 10;
 m12 := TrackBar2.Position / 10;
 m21 := TrackBar3.Position / 10;
 m22 := TrackBar4.Position / 10;
 matrix := TGPMatrix.Create(m11, m12, m21, m22, 0, 0);
 p.SetTransform(matrix);
 p.SetStartCap(LineCapRound);
 p.SetEndCap(LineCapRound);
 g.DrawLine(p, 30, 30, ClientWidth - Panel1.Width - 30, ClientHeight - 30);
 matrix.Free;
 b.Free;
 p.Free;
 g.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
 Repaint;
end;
procedure TForm1.TrackBar2Change(Sender: TObject);
begin
 Repaint;
end;
procedure TForm1.TrackBar3Change(Sender: TObject);
begin
 Repaint;
end;
procedure TForm1.TrackBar4Change(Sender: TObject);
begin
 Repaint;
end;
end.

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