点击按钮时显示按钮被按下的效果

           在实际项目中，为了提供给用户更加好的用户体验，在点击按钮时，要能显示按钮被按下时的状态，给用户一种动态的感觉。

其实这在程序中实现起来也比较容易，只需多一张按钮背景图片即可，在按钮没有按下或者弹起时显示一种状态图，在按钮被压下时

显示另外一种状态图。

            具体实现就是除了写按钮的Click方法，还要写按钮的MouseUp和MouseDown事件。

示例代码如下：

            /// <summary>
            /// 网上订购画面刷新按钮(弹起状态时)
            /// </summary>
            private string strPurchaseRefreshBtnImg = Application.StartupPath + "\\Resources\\" + "btnRefresh.png";
            /// <summary>
            /// 网上订购画面刷新按钮(压下状态时)
            /// </summary>
            private string strPurchaseRefreshBtnDownImg = Application.StartupPath + "\\Resources\\" + "btnRefresh_Down.png";

            /// <summary>
            /// 按下Refresh时发生
            /// </summary>
            /// <param name="sender"></param>
            /// <param name="e"></param>
            private void btnRefresh_MouseDown(object sender, MouseEventArgs e)
            {
                btnRefresh.BackgroundImage = Image.FromFile(strPurchaseRefreshBtnDownImg);
            }
            /// <summary>
            /// 松开Refresh按钮时发生
            /// </summary>
            /// <param name="sender"></param>
            /// <param name="e"></param>
            private void btnRefresh_MouseUp(object sender, MouseEventArgs e)
            {
                btnRefresh.BackgroundImage = Image.FromFile(strPurchaseRefreshBtnImg);
            }

            /// <summary>
            /// 刷新页面
            /// </summary>
            /// <param name="sender"></param>
            /// <param name="e"></param>
            private void btnRefresh_Click(object sender, EventArgs e)
            {
                   //do something...   

            }