再学GDI+[57]: 路径 - Widen

再学GDI+[57]: 路径 - Widen2012-05-12 cnblogs 万一路径的 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.

本例效果图:

代码文件:

unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, StdCtrls;
type
 TForm1 = class（TForm）
  CheckBox1: TCheckBox;
  CheckBox2: TCheckBox;
  procedure FormCreate（Sender: TObject）;
  procedure FormPaint（Sender: TObject）;
  procedure CheckBox1Click（Sender: TObject）;
  procedure CheckBox2Click（Sender: TObject）;
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate（Sender: TObject）;
begin
 CheckBox1.Caption := "执行 Widen";
 CheckBox2.Caption := "显示路径中所有的点";
end;
procedure TForm1.FormPaint（Sender: TObject）;
var
 g: TGPGraphics;
 p: TGPPen;
 b1,b2: TGPBrush;
 path: TGPGraphicsPath;
 pts: array of TGPPoint;
 i: Integer;
begin
 g := 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 then
 begin
  path.Widen（p）;
  g.FillPath（b2, path）;
 end else g.DrawPath（p, path）;
 if CheckBox2.Checked then
 begin
  SetLength（pts, path.GetPointCount）;
  path.GetPathPoints（PGPPoint（pts）, Length（pts））;
  TGPSolidBrush（b1）.SetColor（aclRed）;
  for i := 0 to Length（pts） - 1 do
   g.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）;
begin
 Repaint;
end;
procedure TForm1.CheckBox2Click（Sender: TObject）;
begin
 Repaint;
end;
end.