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 程式師世界 >> 編程語言 >> 更多編程語言 >> Delphi >> 再學GDI+[11]: DrawCurve - 繪制曲線

再學GDI+[11]: DrawCurve - 繪制曲線

編輯:Delphi

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.

窗體文件:object Form1: TForm1
 Left = 0
 Top = 0
 Caption = 'Form1'
 ClientHeight = 187
 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
 object LabeledEdit1: TLabeledEdit
  Left = 208
  Top = 54
  Width = 48
  Height = 21
  EditLabel.Width = 61
  EditLabel.Height = 13
  EditLabel.Caption = 'LabeledEdit1'
  TabOrder = 2
  OnChange = LabeledEdit1Change
 end
 object LabeledEdit2: TLabeledEdit
  Left = 208
  Top = 102
  Width = 48
  Height = 21
  EditLabel.Width = 61
  EditLabel.Height = 13
  EditLabel.Caption = 'LabeledEdit2'
  TabOrder = 3
  OnChange = LabeledEdit2Change
 end
end

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