再学GDI+[49]

再学GDI+[49]2012-05-09 cnblogs 万一路径 - GetPointCount、GetPathPoints、GetLastPoint、GetBounds
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;
  CheckBox3: TCheckBox;
  procedure FormCreate（Sender: TObject）;
  procedure FormPaint（Sender: TObject）;
  procedure CheckBox1Click（Sender: TObject）;
  procedure CheckBox2Click（Sender: TObject）;
  procedure CheckBox3Click（Sender: TObject）;
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate（Sender: TObject）;
begin
 CheckBox1.Caption := "提取路径中所有的点";
 CheckBox2.Caption := "提取路径中最后一个点";
 CheckBox3.Caption := "显示路径的外接矩形";
end;
procedure TForm1.FormPaint（Sender: TObject）;
var
 g: TGPGraphics;
 path: TGPGraphicsPath;
 p: TGPPen;
 b: TGPBrush;
 pts: array[0..6] of TGPPoint;
 ptf: TGPPointF;
 ppts: array of TGPPoint;
 rect: TGPRect;
 i: Integer;
begin
 {给 Bezier 线准备的点, 用于建立路径}
 pts[0].X := 22; pts[0].Y := 44;
 pts[1].X := 11; pts[1].Y := 111;
 pts[2].X := 33; pts[2].Y := 222;
 pts[3].X := 60; pts[3].Y := 88;
 pts[4].X := 80; pts[4].Y := 222;
 pts[5].X := 170; pts[5].Y := 111;
 pts[6].X := 200; pts[6].Y := 11;
 g := TGPGraphics.Create（Canvas.Handle）;
 {建立路径, 并给路径添加两条 Bezier 线}
 path := TGPGraphicsPath.Create;
 path.AddBeziers（PGPPoint（@pts）, Length（pts））;
 {绘制路径}
 p := TGPPen.Create（aclRed）;
 g.DrawPath（p, path）;
 {虚画原始数据点}
 p.SetColor（aclGray）;
 for i := 0 to Length（pts）-1 do
  g.DrawRectangle（p, MakeRect（pts[i].X-2, pts[i].Y-2, 4, 4））;
 {提取路径中所有的点}
 b := TGPSolidBrush.Create（aclBlue）;
 if CheckBox1.Checked then
 begin
  SetLength（ppts, path.GetPointCount）;
  path.GetPathPoints（PGPPoint（ppts）, Length（pts））;
  for i := 0 to Length（ppts）-1 do
   g.FillRectangle（b, MakeRect（ppts[i].X-3, ppts[i].Y-3, 6, 6））;
 end;
 {可以专门获取最后一个点}
 TGPSolidBrush（b）.SetColor（aclRed）;
 if CheckBox2.Checked then
 begin
  path.GetLastPoint（ptf）;
  g.FillRectangle（b, MakeRect（ptf.X-3, ptf.Y-3, 6, 6））;
 end;
 {路径的外接矩形}
 if CheckBox3.Checked then
 begin
  path.GetBounds（rect）;
  g.DrawRectangle（p, rect）;
 end;
 b.Free;
 p.Free;
 path.Free;
 g.Free;
end;
procedure TForm1.CheckBox1Click（Sender: TObject）;
begin
 Repaint;
end;
procedure TForm1.CheckBox2Click（Sender: TObject）;
begin
 Repaint;
end;
procedure TForm1.CheckBox3Click（Sender: TObject）;
begin
 Repaint;
end;
end.