鼠标滚轮问题

将Form的滚轮事件调用控件的滚轮事件，加载完图形后，滚轮不响应，加一句Focus就好了。
private void MouseWheel1(object sender, System.Windows.Forms.MouseEventArgs e)
{
viewControl1.MouseWheel1(sender, e);
}

public void MouseWheel1(object sender, System.Windows.Forms.MouseEventArgs e)
{
m_scale += (int)(e.Delta * 0.02f);
if(m_scale < 1)
{
m_scale = 1f;
}
else if(m_scale > 5)
{
m_scale = 5.0f;
}
((Controls.UserControl1)Parent).UpdateScrollBar();
m_trackBar.SetScale(m_scale);
Invalidate();
}

this.Focus();