再學 GDI+[63]: 路徑畫刷(3) - SetFocusScales、GetFocusScales

本例效果圖:

　　代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls, CheckLst, ExtCtrls, TeCanvas, ComCtrls;
type
　TForm1 = class(TForm)
　　TrackBar1: TTrackBar;
　　TrackBar2: TTrackBar;
　　procedure FormCreate(Sender: TObject);
　　procedure FormDestroy(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure TrackBar1Change(Sender: TObject);
　　procedure TrackBar2Change(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
　rect: TGPRect;
　pb: TGPPathGradIEntBrush;
procedure TForm1.FormCreate(Sender: TObject);
var
　path: TGPGraphicsPath;
　ColorSurround: TGPColor;
　num: Integer;
begin
　rect := MakeRect(10, 10, ClientWidth-40, ClIEntHeight-40);
　path := TGPGraphicsPath.Create;
　path.AddEllipse(rect);
　pb := TGPPathGradIEntBrush.Create(path);
　pb.SetCenterColor(aclLime);
　ColorSurround := aclBlack;
　num := 1;
　pb.SetSurroundColors(@ColorSurround, num);
　path.Free;
　DoubleBuffered := True;
　TrackBar1.Max := 100;
　TrackBar2.Max := 100;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
　pb.Free;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　p: TGPPen;
　x,y: Single;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(aclRed);
　g.FillEllipse(pb, rect);
　pb.SetCenterPoint(MakePoint(rect.X + rect.Width div 2, rect.Y + rect.Height div 2));
　{SetFocusScales}
　pb.SetFocusScales(TrackBar1.Position / 100, TrackBar2.Position / 100);
　{GetFocusScales}
　pb.GetFocusScales(x, y);
　Text := Format('%f,%f',[x,y]);
　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 = 164
　ClIEntWidth = 208
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poDesktopCenter
　OnCreate = FormCreate
　OnDestroy = FormDestroy
　OnPaint = FormPaint
　PixelsPerInch = 96
　TextHeight = 13
　object TrackBar1: TTrackBar
　　Left = 0
　　Top = 143
　　Width = 200
　　Height = 23
　　ShowSelRange = False
　　TabOrder = 0
　　OnChange = TrackBar1Change
　end
　object TrackBar2: TTrackBar
　　Left = 185
　　Top = 0
　　Width = 23
　　Height = 156
　　OrIEntation = trVertical
　　ShowSelRange = False
　　TabOrder = 1
　　OnChange = TrackBar2Change
　end
end