再学 GDI+[34]: TGPPen - 画笔的缩放变换 - ScaleTransform

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.

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