Windows 8 鍵盤上推自訂處理

在Windows 8 應用程式中，當TextBox控制項獲得焦點時，輸入面板會彈出，如 果TextBox控制項處於頁面下半部分，則系統會將頁面上推是的TextBox不被輸入面 板蓋住，但是當TextBox是在FlipView控制項中時，系統不會將頁面上推，所以這種 情況下輸入框被輸入面板蓋住。具體原因不清楚，不知道是不是系統bug。

當輸入面板彈出，頁面上推的操作可以通過監聽InputPane的Showing和Hiding 事件來處理，既然當TextBox在FlipView控制項時，系統沒有很好的處理頁面上推， 那麼開發人員可以通過監聽InputPane的事件來自己處理上推操作。

Windows 8 的一個執行個體代碼Responding to the appearance of the on- screen keyboard sample中介紹了如果監聽處理InputPane的相關操作，參考此實 例以FlipView中的TextBox控制項為例並對執行個體代碼進行簡化處理。

執行個體中的InputPaneHelper是對InputPane的事件處理的封裝，直接拿來使用， InputPaneHelper代碼如下：

using System;   using System.Collections.Generic;   using Windows.UI.ViewManagement;   using Windows.UI.Xaml;   using Windows.Foundation;   using Windows.UI.Xaml.Media.Animation;          namespace HuiZhang212.Keyboard   {       public delegate void InputPaneShowingHandler(object sender, InputPaneVisibilityEventArgs e);       public delegate void InputPaneHidingHandler(InputPane input, InputPaneVisibilityEventArgs e);       public class InputPaneHelper       {           private Dictionary<UIElement, InputPaneShowingHandler> handlerMap;           private UIElement lastFocusedElement = null;           private InputPaneHidingHandler hidingHandlerDelegate = null;                  public InputPaneHelper()           {               handlerMap = new Dictionary<UIElement, InputPaneShowingHandler>();           }                  public void SubscribeToKeyboard(bool subscribe)           {               InputPane input = InputPane.GetForCurrentView();               if (subscribe)               {                   input.Showing += ShowingHandler;                   input.Hiding += HidingHandler;               }               else            {                   input.Showing -= ShowingHandler;                   input.Hiding -= HidingHandler;               }           }                  public void AddShowingHandler(UIElement element, InputPaneShowingHandler handler)           {               if (handlerMap.ContainsKey(element))               {                   throw new System.Exception("A handler is already registered!");               }               else            {                   handlerMap.Add(element, handler);                   element.GotFocus += GotFocusHandler;                   element.LostFocus += LostFocusHandler;               }           }                  private void GotFocusHandler(object sender, RoutedEventArgs e)           {               lastFocusedElement = (UIElement)sender;           }                  private void LostFocusHandler(object sender, RoutedEventArgs e)           {               if (lastFocusedElement == (UIElement)sender)               {                   lastFocusedElement = null;               }           }                  private void ShowingHandler(InputPane sender, InputPaneVisibilityEventArgs e)           {               if (lastFocusedElement != null && handlerMap.Count > 0)               {                   handlerMap[lastFocusedElement](lastFocusedElement, e);               }               lastFocusedElement = null;           }                  private void HidingHandler(InputPane sender, InputPaneVisibilityEventArgs e)           {               if (hidingHandlerDelegate != null)               {                   hidingHandlerDelegate(sender, e);               }               lastFocusedElement = null;           }                  public void SetHidingHandler(InputPaneHidingHandler handler)           {               this.hidingHandlerDelegate = handler;           }                  public void RemoveShowingHandler(UIElement element)           {               handlerMap.Remove(element);               element.GotFocus -= GotFocusHandler;               element.LostFocus -= LostFocusHandler;           }       }   }