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)
Button1: TButton;
Button2: TButton;
procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure FormPaint(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
PtArr: array of TGPPoint;
i: Integer = 0;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
Canvas.Ellipse(X-2, Y-2, X+2, Y+2);
Inc(i);
SetLength(PtArr, i);
PtArr[i-1].X := X;
PtArr[i-1].Y := Y;
Text := IntToStr(i);
end;
procedure TForm1.FormPaint(Sender: TObject);
var
g: TGPGraphics;
p: TGPPen;
begin
g := TGPGraphics.Create(Canvas.Handle);
p := TGPPen.Create(aclRed, 2);
g.Clear(aclWhite);
{如果是動態數組的話, 需要 @PtArr, 但動態數組本身就是個指針}
g.DrawPolygon(p, PGPPoint(PtArr), Length(PtArr));
g.Free;
p.Free;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
i := 0;
SetLength(PtArr, i);
Repaint;
Text := IntToStr(i);
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
Repaint;
end;
end.
