请高手帮我解释一下这段VB小游戏程序！高分赠送。

Dim BallX As Integer

Dim BallY As Integer

Dim AddX As Integer

Dim AddY As Integer

Dim HitX As Integer

Dim W As Integer

Dim H As Integer

Private Sub Command1_Click()

BallX=Int(Rnd(1)＊Form1.ScaleWidth/10)＊5＋25

BallY=Int((Form1.ScaleHeight)/10)＊5

AddX=－5

AddY=－5

Form_Paint

Timer1.Enabled=True

End Sub

Private Sub Command2_Click()

End

End Sub

Private Sub Form_MouseMove(Button As Integer,Shift As Integer,X As Single,Y As Single)

X=X－50

If X<15 Then X=15

If X>W－105 Then X=W－105

HitX=X

If Timer1.Enabled=True Then

Line(16,H－5)－(W－6,H),＆HC0C0C0,BF

Line(HitX,H)－(HitX＋100,H－5),0,BF

End If

End Sub

Private Sub Form_Paint()

Cls

W=Int((ScaleWidth－140)/5)＊5

H=In

Dim BallX As Integer '小球的X轴坐标

Dim BallY As Integer '小球Y轴坐标

Dim AddX As Integer 'X轴增量

Dim AddY As Integer 'Y轴增量

Dim HitX As Integer '准星的X容距量

Dim W As Integer

Dim H As Integer

Private Sub Command1_Click()

BallX=Int(Rnd(1)＊Form1.ScaleWidth/10)＊5＋25 '随机产生小球X坐标值

BallY=Int((Form1.ScaleHeight)/10)＊5 '随机产生小球Y坐标值

AddX=－5 '小球左移5个单位(可能是像素)

AddY=－5 '小球上移5个单位

Form_Paint '窗体绘制事件

Timer1.Enabled=True '定时器激活

End Sub

Private Sub Command2_Click()

End '程序终止

End Sub

Private Sub Form_MouseMove(Button As Integer,Shift As Integer,X As Single,Y As Single) '鼠标移动事件

X=X－50 '设置鼠标(准星)与小球X坐标偏差

If X<15 Then X=15

If X>W－105 Then X=W－105

HitX=X '返回捕获X坐标值

If Timer1.Enabled=True Then '如果定时器状态为激活