C#：为PrintPreviewControl加上鼠标滚轮支持和鼠标拖动预览页支持

最近做项目的时候需要使用到PrintPreviewControl来实现打印预览。

使用PrintPreviewControl的好处是，比PrintPreviewDialog要来的灵活。

PrintPreviewControl可以放置在任何你需要的地方，而不用特别的弹出一个对话框。并且可以实现任何你需要的按钮功能。

 

废话不说，放上代码

 

#region ■宣言_________________________________________________________ private FieldInfo m_Position; private MethodInfo m_SetPositionMethod; private bool isMouseDown; private Point startPosition; private Point endPosition; private Point curPos; #endregion

#region ■初期化_______________________________________________________ public TestForm() { Type type = typeof(System.Windows.Forms.PrintPreviewControl); m_Position = type.GetField("position", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Ex<mce:script type="text/javascript" src="http://hi.images.youkuaiyun.com/js/blog/tiny_mce/themes/advanced/langs/zh.js" mce_src="http://hi.images.youkuaiyun.com/js/blog/tiny_mce/themes/advanced/langs/zh.js"></mce:script><mce:script type="text/javascript" src="http://hi.images.youkuaiyun.com/js/blog/tiny_mce/plugins/syntaxhl/langs/zh.js" mce_src="http://hi.images.youkuaiyun.com/js/blog/tiny_mce/plugins/syntaxhl/langs/zh.js"></mce:script>actBinding); m_SetPositionMethod = type.GetMethod("SetPositionNoInvalidate", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.ExactBinding); //ppcPreview就是PrintPreviewControl的实例 ppcPreview.MouseWheel += new MouseEventHandler(ppcPreview_MouseWheel); ppcPreview.Click+=new EventHandler(ppcPreview_Click); ppcPreview.MouseDown+=new MouseEventHandler(ppcPreview_MouseDown); ppcPreview.MouseUp+=new MouseEventHandler(ppcPreview_MouseUp); ppcPreview.MouseMove+=new MouseEventHandler(ppcPreview_MouseMove); this.MouseWheel += new MouseEventHandler(ppcPreview_MouseWheel); } #endregion

#region ■事件处理_____________________________________________________ /// <summary> /// 鼠标滚轮 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> void ppcPreview_MouseWheel(object sender, MouseEventArgs e) { if (!SystemInformation.MouseWheelPresent) { //If have no wheel return; } int scrollAmount; float amount = Math.Abs(e.Delta) / SystemInformation.MouseWheelScrollDelta; amount *= SystemInformation.MouseWheelScrollLines; amount *= 12;//Row height amount *= (float)ppcPreview.Zoom;//Zoom Rate if (e.Delta < 0) { scrollAmount = (int)amount; } else { scrollAmount = -(int)amount; } Point curPos = (Point)(m_Position.GetValue(ppcPreview)); m_SetPositionMethod.Invoke(ppcPreview, new object[] { new Point(curPos.X + 0, curPos.Y + scrollAmount) }); } /// <summary> /// 鼠标在控件上点击时，需要处理获得焦点，因为默认不会获得焦点 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void ppcPreview_Click(object sender, EventArgs e) { ppcPreview.Select(); ppcPreview.Focus(); } /// <summary> /// 鼠标按下，开始拖动 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void ppcPreview_MouseDown(object sender, MouseEventArgs e) { isMouseDown = true; startPosition = new Point(e.X, e.Y); curPos = (Point)(m_Position.GetValue(ppcPreview)); } /// <summary> /// 鼠标释放，完成拖动 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void ppcPreview_MouseUp(object sender, MouseEventArgs e) { isMouseDown = false; endPosition = new Point(e.X, e.Y); m_SetPositionMethod.Invoke(ppcPreview, new object[] { new Point(curPos.X + (startPosition.X - endPosition.X), curPos.Y + (startPosition.Y - endPosition.Y)) }); } /// <summary> /// 鼠标移动，拖动中 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void ppcPreview_MouseMove(object sender, MouseEventArgs e) { if (isMouseDown == true) { endPosition = new Point(e.X, e.Y); m_SetPositionMethod.Invoke(ppcPreview, new object[] { new Point(curPos.X + (startPosition.X - endPosition.X), curPos.Y + (startPosition.Y - endPosition.Y)) }); } }