动态调整 TBitBtn 上的图片 - 回复 "游戏而已" 的问题

问题来源： http://www.cnblogs.com/del/archive/2011/02/11/1951641.html#2025348

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测试图片：

测试代码：

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unit Unit1;



interface



uses

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

  Dialogs, StdCtrls, Buttons;



type

  TForm1 = class(TForm)

    BitBtn1: TBitBtn;

    procedure FormCreate(Sender: TObject);

    procedure FormDestroy(Sender: TObject);

    procedure BitBtn1MouseLeave(Sender: TObject);

    procedure BitBtn1MouseEnter(Sender: TObject);

    procedure BitBtn1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);

    procedure BitBtn1MouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);

  private

    procedure ChangeBitmap(Sender: TObject);

  public

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses jpeg;



const picPath = 'C:\Temp\btn_sys_close.jpg';

var

  tag2: Integer = -1;

  jpg: TJPEGImage;

  bit: TBitmap;



procedure TForm1.FormCreate(Sender: TObject);

begin

  if not FileExists(picPath) then begin beep; Application.Terminate; end;

  jpg := TJPEGImage.Create;

  jpg.LoadFromFile(picPath);

  bit := TBitmap.Create;

  bit.SetSize(jpg.Width div 3, jpg.Height);

  BitBtn1.OnMouseLeave(BitBtn1);

end;



{被重复调用的过程}

procedure TForm1.ChangeBitmap(Sender: TObject);

begin

  if tag2 = TControl(Sender).Tag then Exit;

  tag2 := TControl(Sender).Tag;

  bit.Canvas.Draw(-bit.Width * tag2, 0, jpg);

  TBitBtn(Sender).Glyph := bit;

end;



procedure TForm1.BitBtn1MouseLeave(Sender: TObject);

begin

  TControl(Sender).Tag := 0;

  ChangeBitmap(Sender);

end;



procedure TForm1.BitBtn1MouseEnter(Sender: TObject);

begin

  TControl(Sender).Tag := 1;

  ChangeBitmap(Sender);

end;



procedure TForm1.BitBtn1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);

begin

  TControl(Sender).Tag := 2;

  ChangeBitmap(Sender);

end;



procedure TForm1.BitBtn1MouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);

begin

  TControl(Sender).Tag := 1;

  ChangeBitmap(Sender);

end;



procedure TForm1.FormDestroy(Sender: TObject);

begin

  jpg.Free;

  bit.Free;

end;



end.

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