路径的 Widen 方法可以把路径中的线, 根据指定画笔的宽度与样式, 转换为一个范围(有点类似区域); 但转换后再描绘路径就只能使用 FillPath 而不是 DrawPath 了. 本例没有测试它的两个默认参数, 因为前面已多次提到了.

unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls;typeTForm1 = class(TForm)CheckBox1: TCheckBox;CheckBox2: TCheckBox;procedure FormCreate(Sender: TObject);procedure FormPaint(Sender: TObject);procedure CheckBox1Click(Sender: TObject);procedure CheckBox2Click(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}uses GDIPOBJ, GDIPAPI;procedure TForm1.FormCreate(Sender: TObject);
beginCheckBox1.Caption := '执行 Widen';CheckBox2.Caption := '显示路径中所有的点';
end;procedure TForm1.FormPaint(Sender: TObject);
varg: TGPGraphics;p: TGPPen;b1,b2: TGPBrush;path: TGPGraphicsPath;pts: array of TGPPoint;i: Integer;
beging := TGPGraphics.Create(Canvas.Handle);p := TGPPen.Create(aclSlateGray, 20);p.SetEndCap(LineCapArrowAnchor);b1 := TGPSolidBrush.Create(aclRed);b2 := TGPHatchBrush.Create(HatchStyleDiagonalCross, aclSilver, aclSlateGray);path := TGPGraphicsPath.Create;path.AddLine(40, 50, ClientWidth-40, 50);if CheckBox1.Checked thenbeginpath.Widen(p);g.FillPath(b2, path);end else g.DrawPath(p, path);if CheckBox2.Checked thenbeginSetLength(pts, path.GetPointCount);path.GetPathPoints(PGPPoint(pts), Length(pts));TGPSolidBrush(b1).SetColor(aclRed);for i := 0 to Length(pts) - 1 dog.FillRectangle(b1, pts[i].X-3, pts[i].Y-3, 6, 6);end;path.Free;b1.Free;b2.Free;p.Free;g.Free;
end;procedure TForm1.CheckBox1Click(Sender: TObject);
beginRepaint;
end;procedure TForm1.CheckBox2Click(Sender: TObject);
beginRepaint;
end;end.

窗体文件:

object Form1: TForm1Left = 0Top = 0Caption = 'Form1'ClientHeight = 136ClientWidth = 287Color = clBtnFaceFont.Charset = DEFAULT_CHARSETFont.Color = clWindowTextFont.Height = -11Font.Name = 'Tahoma'Font.Style = []OldCreateOrder = FalsePosition = poDesktopCenterOnCreate = FormCreateOnPaint = FormPaintPixelsPerInch = 96TextHeight = 13object CheckBox1: TCheckBoxLeft = 43Top = 104Width = 97Height = 17Caption = 'CheckBox1'TabOrder = 0OnClick = CheckBox1Clickendobject CheckBox2: TCheckBoxLeft = 138Top = 104Width = 125Height = 17Caption = 'CheckBox2'TabOrder = 1OnClick = CheckBox2Clickend
end