再学 GDI+[5]: DrawArc - 绘制弧线

本例效果图:

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代码文件:

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unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, Spin, ExtCtrls;



type

  TForm1 = class(TForm)

    Panel1: TPanel;

    Label1: TLabel;

    Label2: TLabel;

    SpinEdit1: TSpinEdit;

    SpinEdit2: TSpinEdit;

    procedure FormCreate(Sender: TObject);

    procedure FormPaint(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses GDIPOBJ, GDIPAPI;



var

  a1,a2: Integer;



procedure TForm1.FormCreate(Sender: TObject);

begin

  a1 := 0;

  a2 := 360;

  SpinEdit1.Text := IntToStr(a1);

  SpinEdit2.Text := IntToStr(a2);

  SpinEdit1.Increment := 10;

  SpinEdit2.Increment := 10;

  SpinEdit1.OnChange := FormPaint;

  SpinEdit2.OnChange := FormPaint;

end;



procedure TForm1.FormPaint(Sender: TObject);

var

  g: TGPGraphics;

  p: TGPPen;

  x,y,w,h: Integer;

begin

  g := TGPGraphics.Create(Canvas.Handle);

  p := TGPPen.Create(aclRed, 2);

  g.Clear(aclWhite);



  x := ClientWidth div 6;

  y := ClientHeight div 6;

  w := x * 4;

  h := y * 3;

  a1 := StrToIntDef(SpinEdit1.Text, 0);

  a2 := StrToIntDef(SpinEdit2.Text, 360);



  g.DrawArc(p, x, y, w, h, a1, a2);



  g.Free;

  p.Free;

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 184

  ClientWidth = 258

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesktopCenter

  OnCreate = FormCreate

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

  object Panel1: TPanel

    Left = 0

    Top = 151

    Width = 258

    Height = 33

    Align = alBottom

    BevelOuter = bvNone

    TabOrder = 0

    ExplicitLeft = 8

    ExplicitTop = 96

    ExplicitWidth = 257

    object Label2: TLabel

      Left = 136

      Top = 8

      Width = 52

      Height = 13

      Caption = #26059#36716#35282#24230':'

    end

    object Label1: TLabel

      Left = 8

      Top = 8

      Width = 52

      Height = 13

      Caption = #36215#22987#35282#24230':'

    end

    object SpinEdit2: TSpinEdit

      Left = 194

      Top = 3

      Width = 55

      Height = 22

      MaxValue = 0

      MinValue = 0

      TabOrder = 0

      Value = 0

    end

    object SpinEdit1: TSpinEdit

      Left = 66

      Top = 3

      Width = 55

      Height = 22

      MaxValue = 0

      MinValue = 0

      TabOrder = 1

      Value = 0

    end

  end

end