Delphi中用多媒體庫Bass.dll播放mp3 [10] - 使用回調函數(2)

窗體文件:

object Form1: TForm1
　 Left = 222
　 Top = 114
　 Caption = 'Form1'
　 ClIEntHeight = 84
　 ClIEntWidth = 254
　 Color = clBtnFace
　 Font.Charset = DEFAULT_CHARSET
　 Font.Color = clWindowText
　 Font.Height = -11
　 Font.Name = 'Tahoma'
　 Font.Style = []
　 OldCreateOrder = False
　 Position = poDesigned
　 OnCreate = FormCreate
　 OnDestroy = FormDestroy
　 PixelsPerInch = 96
　 TextHeight = 13
　 object Button1: TButton
　　 Left = 8
　　 Top = 18
　　 Width = 75
　　 Height = 25
　　 Caption = #25171#24320
　　 TabOrder = 0
　　 OnClick = Button1Click
　 end
　 object Button2: TButton
　　 Left = 89
　　 Top = 18
　　 Width = 75
　　 Height = 25
　　 Caption = #25773#25918
　　 TabOrder = 1
　　 OnClick = Button2Click
　 end
　 object Button3: TButton
　　 Left = 170
　　 Top = 18
　　 Width = 75
　　 Height = 25
　　 Caption = #26242#20572
　　 TabOrder = 2
　　 OnClick = Button3Click
　 end
　 object TrackBar1: TTrackBar
　　 Left = 1
　　 Top = 53
　　 Width = 250
　　 Height = 28
　　 TabOrder = 3
　 end
　 object OpenDialog1: TOpenDialog
　　 Left = 72
　　 Top = 32
　 end
　 object Timer1: TTimer
　　 OnTimer = Timer1Timer
　　 Left = 152
　　 Top = 32
　 end