再學 GDI+[34]: TGPPen - 畫筆的縮放變換 - ScaleTransform

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;
　　TrackBar2: TTrackBar;
　　procedure FormCreate(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure TrackBar1Change(Sender: TObject);
　　procedure TrackBar2Change(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　TrackBar1.ShowSelRange := False;
　TrackBar1.Height := 20;
　TrackBar1.Min := 1;
　TrackBar1.Max := 100;
　TrackBar1.Position := 10;
　TrackBar2.ShowSelRange := False;
　TrackBar2.Height := 20;
　TrackBar2.Min := 1;
　TrackBar2.Max := 100;
　TrackBar2.Position := 10;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　p: TGPPen;
　r: TRect;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(aclBrown, 3);
　p.ScaleTransform(TrackBar1.Position / 10, TrackBar2.Position / 10);
　r := ClIEntRect;
　InflateRect(r, -30, -30);
　OffsetRect(r, 0, -10);
　g.DrawEllipse(p, MakeRect(r));
　p.Free;
　g.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.TrackBar2Change(Sender: TObject);
begin
　Repaint;
end;
end.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 196
　ClIEntWidth = 296
　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 = 2
　　Top = 172
　　Width = 143
　　Height = 45
　　TabOrder = 0
　　OnChange = TrackBar1Change
　end
　object TrackBar2: TTrackBar
　　Left = 151
　　Top = 172
　　Width = 143
　　Height = 45
　　TabOrder = 1
　　OnChange = TrackBar2Change
　end
end