下面的四个事件一定要绑定，不绑定的话是没有任何效果的。。。private Point m_ptStart = new Point(0, 0); private Point m_ptEnd = new Point(0, 0); // true: MouseUp or false: MouseMove private bool m_bMouseDown = false; private void pictureBox1_MouseDown(object sender, MouseEventArgs e) { if (e.Button != MouseButtons.Left) { return; } if (!m_bMouseDown) { m_ptStart = new Point(e.X, e.Y); m_ptEnd = new Point(e.X, e.Y); } m_bMouseDown = !m_bMouseDown; } private void pictureBox1_MouseUp(object sender, MouseEventArgs e) { if (e.Button != MouseButtons.Left) {...