再学 GDI+[10] DrawClosedCurve - 绘制闭合曲线

 

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ComCtrls;

type
  TForm1 = class(TForm)
    TrackBar1: TTrackBar;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormPaint(Sender: TObject);
    procedure TrackBar1Change(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
uses
  GDIPOBJ,GDIPAPI;
var
  i:Integer = 0;
  PtArr:array of TGPPoint;
  tension:Single;
procedure TForm1.Button1Click(Sender: TObject);
begin
  i:=0;
  SetLength(PtArr,i);
  Repaint;
  Text:=IntToStr(i);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Button1.Caption:='擦除';
  TrackBar1.ShowSelRange:=False;
  TrackBar1.Min:=-25;
  TrackBar1.Max:=35;
  TrackBar1.Position:=5;
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  Inc(i);
  SetLength(PtArr,i);
  PtArr[i-1]:=MakePoint(x,y);
  Text:=IntToStr(i);
  Repaint;
end;

procedure TForm1.FormPaint(Sender: TObject);
var
  g:TGPGraphics;
  p:TGPPen;
  i:Integer;
begin
  g:=TGPGraphics.Create(Canvas.Handle);
  g.Clear(aclWhite);
  p:=TGPPen.Create(aclRed,2);

  {最后一个参数是可选的, 默认值是 0.5, 为 0 时曲线会转为直线段}
  g.DrawClosedCurve(p,PGPPoint(PtArr),Length(PtArr),tension);

  p.SetWidth(1);
  p.SetColor(aclBlack);
  for i := 0 to Length(PtArr) - 1 do
    begin
      g.DrawEllipse(p,ptarr[i].X-2,ptarr[i].Y-2,4,4);
    end;
  p.Free;
  g.Free;
end;

procedure TForm1.TrackBar1Change(Sender: TObject);
begin
  tension:=TrackBar1.Position / 10;
  Repaint;
end;

end.