本例效果圖:
代碼文件:unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ComCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
TrackBar1: TTrackBar;
procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure FormPaint(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure TrackBar1Change(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
PtArr: array of TGPPoint;
i: Integer = 0;
tension: Single;
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].X := X;
PtArr[i-1].Y := Y;
Text := IntToStr(i);
Repaint;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
g: TGPGraphics;
p: TGPPen;
i: Integer;
begin
g := TGPGraphics.Create(Canvas.Handle);
p := TGPPen.Create(aclRed, 2);
g.Clear(aclWhite);
{最後一個參數是可選的, 默認值是 0.5, 為 0 時曲線會轉為直線段}
g.DrawClosedCurve(p, PGPPoint(PtArr), Length(PtArr), tension);
p.SetWidth(1);
p.SetColor(aclBlack);
for i := 0 to Length(PtArr) - 1 do
g.DrawEllipse(p, PtArr[i].X-2, PtArr[i].Y-2, 4, 4);
g.Free;
p.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
tension := TrackBar1.Position / 10;
Repaint;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
i := 0;
SetLength(PtArr, i);
Repaint;
Text := IntToStr(i);
end;
end.
窗體文件:object Form1: TForm1
Left = 0
Top = 0
Caption = 'Form1'
ClientHeight = 188
ClientWidth = 264
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
Position = poDesktopCenter
OnCreate = FormCreate
OnMouseUp = FormMouseUp
OnPaint = FormPaint
PixelsPerInch = 96
TextHeight = 13
object Button1: TButton
Left = 181
Top = 155
Width = 75
Height = 25
Caption = 'Button1'
TabOrder = 0
OnClick = Button1Click
end
object TrackBar1: TTrackBar
Left = 8
Top = 155
Width = 167
Height = 25
TabOrder = 1
OnChange = TrackBar1Change
end
end
