有一个名称为Fom1的窗体,上面没有控件,设有以下程序(其中方法PSet(X,Y)的功能是在坐标X,Y处画一个点)。
Dim cmdmave As Boolean
Private Sub Form_MouseDown(Button As Integer,Shift As Integer,X As Single,Y As Single)
cmdmave=True
End Sub
Private Sub Form MouseMove(Button As Integer,Shift As Integer,X As Single,Y As Single)
If cmdmave Then
Form1.PSet(X,Y)
End If
End Sub
Private Sub Form_MouseUp(Button As Integer,Shift As Integer,X As Single,Y As Single)
cmdmave=False
End Sub
此程序的功能是______。
A) 每按下鼠标键一次,在鼠标所指位置画一个点
B) 按下鼠标键,则在鼠标所指位置画一个点;放开鼠标键,则此点消失
C) 不按鼠标键而拖动鼠标,则沿鼠标拖动的轨迹画一条线
D) 按下鼠标键并拖动鼠标,则沿鼠标拖动的轨迹画一条线,放开鼠标键则结束画线