【C#】添加鼠标管轮事件

对FlowLayoutPanel添加鼠标滚轮事件

在mainform中添加事件

his.flowLayoutPanel1.MouseWheel +=
                new System.Windows.Forms.MouseEventHandler(this.flowLayoutPanel1_MouseWheel);

添加滚轮事件函数：

private void flowLayoutPanel1_MouseWheel(object sender, MouseEventArgs e)
{
     if (!(flowLayoutPanel1.VerticalScroll.Visible == false || (flowLayoutPanel1.VerticalScroll.Value ==  && e.Delta > ) || (flowLayoutPanel1.VerticalScroll.Value == lastRightPanelVerticalScrollValue && e.Delta < )))
     {
          flowLayoutPanel1.VerticalScroll.Value += ;
          lastRightPanelVerticalScrollValue = flowLayoutPanel1.VerticalScroll.Value;
          flowLayoutPanel1.Refresh();
          flowLayoutPanel1.Invalidate();
          flowLayoutPanel1.Update();
     }
}

除此之外还要说的一点是，触发鼠标的滚动事件后，处理事件的函数参数 MouseEventArgs e 中有个Delta属性，默认情况下向上滚动e.Delta=120，向下滚动e.Delta=-120。以上的程序还不是特别完美，因为当Panel控件较大而没有显示滚动条时，或滚动条已在最上方而滚轮又是向上滚动，或滚动条已在最下方而滚轮又是向下滚动时，同样会执行Panel.Refresh();Panel.Invalidate();Panel.Update();等窗体重绘代码，占用较多资源。因此可以在执行这些代码前先对Panel的当前状况做判断。

int lastRightPanelVerticalScrollValue = -;//为鼠标滚动事件提供一个静态变量，用来存储上次滚动后的VerticalScroll.Value

添加FlowLayoutPanel的鼠标进入事件和鼠标点击事件

private void flowLayoutPanel1_MouseEnter(object sender, EventArgs e)
{
      flowLayoutPanel1.Focus();
}
private void flowLayoutPanel1_MouseClick(object sender, MouseEventArgs e)
{
      flowLayoutPanel1.Focus();
}