通过路径的辅助类 TGPGraphicsPathIterator , 可以获得更多路径数据和控制能力.
本例效果图:
![](https://www.cnblogs.com/images/cnblogs_com/del/138617/o_86221.gif)
代码文件:
本例效果图:
![](https://www.cnblogs.com/images/cnblogs_com/del/138617/o_86221.gif)
代码文件:
unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm1 = class(TForm) Button1: TButton; Button2: TButton; procedure FormCreate(Sender: TObject); procedure FormDestroy(Sender: TObject); procedure FormPaint(Sender: TObject); procedure Button1Click(Sender: TObject); procedure Button2Click(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} uses GDIPOBJ, GDIPAPI; var path: TGPGraphicsPath; procedure TForm1.FormCreate(Sender: TObject); var pt1, pt2: TPoint; begin Button1.Caption := '查看路径基本数据'; Button2.Caption := '重绘路径中的子路径'; pt1 := Point(30, 20); pt2 := Point(150, 120); {建立路径, 并添加四个子图形} path := TGPGraphicsPath.Create; path.StartFigure; path.AddRectangle(MakeRect(Rect(pt1, pt2))); path.CloseFigure; path.StartFigure; path.AddEllipse(MakeRect(Rect(pt1, pt2))); path.CloseFigure; path.StartFigure; path.AddLine(pt1.X, pt1.Y, pt2.X, pt2.Y); path.CloseFigure; path.StartFigure; path.AddLine(pt1.X, pt2.Y, pt2.X, pt1.Y); path.CloseFigure; end; procedure TForm1.FormDestroy(Sender: TObject); begin path.Free; end; procedure TForm1.FormPaint(Sender: TObject); var g: TGPGraphics; p: TGPPen; begin g := TGPGraphics.Create(Canvas.Handle); p := TGPPen.Create(aclSilver, 2); g.DrawPath(p, path); p.Free; g.Free; end; procedure TForm1.Button1Click(Sender: TObject); var PathIterator: TGPGraphicsPathIterator; str: string; begin PathIterator := TGPGraphicsPathIterator.Create(path); str := str + Format('路径中的总点数: %d', [PathIterator.GetCount]); str := str + Format(sLineBreak + '路径中的子路径数: %d', [PathIterator.GetSubpathCount]); str := str + Format(sLineBreak + '路径中是否包含曲线: %s', [BoolToStr(PathIterator.HasCurve, True)]); ShowMessage(str); PathIterator.Free; end; procedure TForm1.Button2Click(Sender: TObject); const ColorArr: array[0..3] of TGPColor = (aclRed, aclGreen, aclBlue, aclYellow); var PathIterator: TGPGraphicsPathIterator; PathSection: TGPGraphicsPath; bool: LongBool; g: TGPGraphics; p: TGPPen; i: Integer; begin g := TGPGraphics.Create(Canvas.Handle); p := TGPPen.Create(aclRed, 2); PathIterator := TGPGraphicsPathIterator.Create(path); PathIterator.Rewind; {到路径起始点} for i := 0 to PathIterator.GetSubpathCount - 1 do begin PathSection := TGPGraphicsPath.Create; PathIterator.NextSubpath(PathSection, bool); p.SetColor(ColorArr[i]); g.DrawPath(p, PathSection); PathSection.Free; end; PathIterator.Free; p.Free; g.Free; end; end.窗体文件:
object Form1: TForm1 Left = 0 Top = 0 Caption = 'Form1' ClientHeight = 198 ClientWidth = 181 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 Button1: TButton Left = 24 Top = 134 Width = 137 Height = 25 Caption = 'Button1' TabOrder = 0 OnClick = Button1Click end object Button2: TButton Left = 24 Top = 165 Width = 137 Height = 25 Caption = 'Button2' TabOrder = 1 OnClick = Button2Click end end