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.
