再學 GDI+[49]: 路徑 - GetPointCount、GetPathPoints、GetLastPoint、GetBounds

本例效果圖:

　　代碼文件: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 := '提取路徑中所有的點';
　CheckBox2.Caption := '提取路徑中最後一個點';
　CheckBox3.Caption := '顯示路徑的外接矩形';
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
　{給 BezIEr 線准備的點, 用於建立路徑}
　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);
　{建立路徑, 並給路徑添加兩條 BezIEr 線}
　path := TGPGraphicsPath.Create;
　path.AddBezIErs(PGPPoint(@pts), Length(pts));
　{繪制路徑}
　p := TGPPen.Create(aclRed);
　g.DrawPath(p, path);
　{虛畫原始數據點}
　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));
　{提取路徑中所有的點}
　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;
　{可以專門獲取最後一個點}
　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;
　{路徑的外接矩形}
　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.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 235
　ClIEntWidth = 302
　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 CheckBox1: TCheckBox
　　Left = 157
　　Top = 152
　　Width = 124
　　Height = 17
　　Caption = 'CheckBox1'
　　TabOrder = 0
　　OnClick = CheckBox1Click
　end
　object CheckBox2: TCheckBox
　　Left = 157
　　Top = 175
　　Width = 137
　　Height = 17
　　Caption = 'CheckBox2'
　　TabOrder = 1
　　OnClick = CheckBox2Click
　end
　object CheckBox3: TCheckBox
　　Left = 157
　　Top = 198
　　Width = 137
　　Height = 17
　　Caption = 'CheckBox3'
　　TabOrder = 2
　　OnClick = CheckBox3Click
　end
end