Public Class Form1
    Dim beginDraw As Boolean
    Dim m_ptNow As Point = New Point(0, 0)

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        beginDraw = False
    End Sub
    Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
        If My.Computer.Keyboard.CtrlKeyDown Then
            beginDraw = True
        Else
            beginDraw = False
        End If
        If beginDraw Then
            m_ptNow.X = e.X
            m_ptNow.Y = e.Y
            Me.PictureBox1.Refresh()
        End If
    End Sub

    Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
        If beginDraw Then
            e.Graphics.DrawEllipse(Pens.Red, m_ptNow.X, m_ptNow.Y, 50, 50)
        End If
    End Sub

End Class

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• 24
• 25
• 26
• 27

在按下ctrl键后，随着鼠标移动，在鼠标移动处画圆