如何使用AddHandler在WPF中的按鈕上為LostKeyBoardFocusEvent添加事件處理程序

Question

我正在嘗試封裝一些按鈕行為，其中之一是為事件“ LostKeyboardFocusEvent”添加事件處理程序，但是在運行時使用和SystemArgumentException出現“處理程序類型不匹配”錯誤：

AssociatedObject.AddHandler(Button.LostKeyboardFocusEvent, new DependencyPropertyChangedEventHandler(HandleButtonToolTip), true);

public static void HandleButtonToolTip(object sender, DependencyPropertyChangedEventArgs e)
        {
            //Get tooltip from sender.
            ToolTip tt = (ToolTip)(sender as Control).ToolTip;
            if ((sender as Control).IsKeyboardFocusWithin && !tt.IsOpen)
            {
                ShowButtonTooltip(sender);
            }
            else
            {
                ClearButtonTooltip();
            }
        }

任何幫助表示贊賞！

Answer 1

更改

AssociatedObject.AddHandler(Button.LostKeyboardFocusEvent, new DependencyPropertyChangedEventHandler(HandleButtonToolTip), true);

至

AssociatedObject.AddHandler(Button.LostKeyboardFocusEvent, new RoutedEventHandler(HandleButtonToolTip), true);

並改變

public static void HandleButtonToolTip(object sender, DependencyPropertyChangedEventArgs e)

至

public static void HandleButtonToolTip(object sender, RoutedEventArgs e)

Answer 2

只需將處理程序的類型從DependencyPropertyChangedEventArgs更改為KeyboardFocusChangedEventHandler ：

AssociatedObject.AddHandler(Button.LostKeyboardFocusEvent, new KeyboardFocusChangedEventHandler(HandleButtonToolTip), true);

...以及EventArgs的類型為KeyboardFocusChangedEventArgs ：

public static void HandleButtonToolTip(object sender, KeyboardFocusChangedEventArgs e)
...