再學 GDI+[55]: 路徑 - Flatten

通過路徑的 Flatten 方法可以把路徑中的曲線拉直, 拉直到什麼程度是由它的第二個參數(默認0.25)決定的; 它的第一個參數又是一個矩陣變換, 也就是說 Flatten 可以同時進行矩陣變換, 本例沒有測試它, 其詳情參見:

　　http://www.cnblogs.com/del/archive/2008/06/20/1226293.Html

　　本例效果圖:

　　代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, ComCtrls;
type
　TForm1 = class(TForm)
　　TrackBar1: TTrackBar;
　　procedure FormPaint(Sender: TObject);
　　procedure FormCreate(Sender: TObject);
　　procedure TrackBar1Change(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　TrackBar1.Height := 23;
　TrackBar1.ShowSelRange := False;
　TrackBar1.Min := -5000;
　TrackBar1.Max := 5000;
　TrackBar1.Position := 25;
　TrackBar1.PageSize := 5;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　p: TGPPen;
　path: TGPGraphicsPath;
　f: Single;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(aclBlue, 2);
　path := TGPGraphicsPath.Create;
　path.AddEllipse(20, 20, ClientWidth-40, ClIEntHeight- 80);
　f := TrackBar1.Position / 100;
　path.Flatten(nil, f);
　Text := Format('%f', [f]);
　g.DrawPath(p, path);
　path.Free;
　p.Free;
　g.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
　Repaint;
end;
end.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 200
　ClIEntWidth = 264
　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 = 0
　　Top = 176
　　Width = 265
　　Height = 45
　　TabOrder = 0
　　OnChange = TrackBar1Change
　end
end