本例效果圖:
代碼文件:unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ComCtrls, ExtCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
TrackBar1: TTrackBar;
LabeledEdit1: TLabeledEdit;
LabeledEdit2: TLabeledEdit;
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);
procedure LabeledEdit1Change(Sender: TObject);
procedure LabeledEdit2Change(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';
LabeledEdit1.EditLabel.Caption := '起始點';
LabeledEdit2.EditLabel.Caption := '有效點數';
LabeledEdit1.Text := '0';
LabeledEdit2.Text := '0';
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;
LabeledEdit2.Text := IntToStr(i-1);
Text := IntToStr(i);
Repaint;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
g: TGPGraphics;
p: TGPPen;
i,n1,n2: Integer;
begin
g := TGPGraphics.Create(Canvas.Handle);
p := TGPPen.Create(aclRed, 2);
g.Clear(aclWhite);
n1 := StrToIntDef(LabeledEdit1.Text, 0);
n2 := StrToIntDef(LabeledEdit2.Text, Length(PtArr)-1);
{後面三個參數是可選的, 最後參數的默認值是 0.5, 為 0 時曲線會轉為直線段}
g.DrawCurve(p, PGPPoint(PtArr), Length(PtArr), n1, n2, 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.LabeledEdit1Change(Sender: TObject);
var
a,b: Integer;
begin
a := StrToIntDef(LabeledEdit1.Text, 0);
if (a < 0) or (a > Length(PtArr) - 2) then
LabeledEdit1.Text := IntToStr(0);
a := StrToIntDef(LabeledEdit1.Text, 0);
b := StrToIntDef(LabeledEdit2.Text, 0);
if a+b > Length(PtArr)-1 then
LabeledEdit2.Text := IntToStr(Length(PtArr)-1-a);
Repaint;
end;
procedure TForm1.LabeledEdit2Change(Sender: TObject);
var
a,b: Integer;
begin
a := StrToIntDef(LabeledEdit1.Text, 0);
b := StrToIntDef(LabeledEdit2.Text, 0);
if (b < 0) or (b >= Length(PtArr) - a) then
LabeledEdit2.Text := IntToStr(Length(PtArr)-1-a);
Repaint;
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.
