防止键盘事件在 Flutter 中冒泡（传播给父母）

Posted 2023-03-17

【中文标题】防止键盘事件在 Flutter 中冒泡（传播给父母）

【英文标题】：Prevent keyboard event from bubbling (propagating to parents) in Flutter

【发布时间】：2021-07-01 21:52:46

【问题描述】：

我正在使用 RawKeyboardListener 检测转义键以关闭（弹出）窗口，但我无法使用该事件并防止它冒泡（传播）到父窗口，因此所有父窗口将收到逃逸并关闭！

我尝试使用 Focus 元素，它也是 onKey，但没有区别。

return Scaffold(
  body: RawKeyboardListener(
    focusNode: FocusNode(),
    onKey: (RawKeyEvent event) 
      if (event.logicalKey == LogicalKeyboardKey.escape) 
      Navigator.pop(context);
    ,
    autofocus: true,
    child: Container(
      child: Text("blah blah")
      ),
    ),
  ),
);

【问题讨论】：

“我正在使用 RawKeyboardListener 检测转义键” - 您的代码不会以任何方式检测转义键：您无条件调用 pop() 方法

只是问题中的错字，已更新，谢谢。

事件不会冒泡到父窗口（页面）：现在你的onKey 被调用了两次（用于按键向下和向上）

是的，冒泡了，我加了日志。

【参考方案1】：

您可以将键监听器附加到焦点节点，此监听器将返回一个 KeyEventResult 枚举，确定是否处理了键事件

   var focus = FocusNode(onKey: (FocusNode node, RawKeyEvent event) 
      if (event.logicalKey == LogicalKeyboardKey.escape)
      
        return KeyEventResult.handled;
      
      return KeyEventResult.ignored;
    );

这里还有 KeyEventResult 描述：

/// An enum that describes how to handle a key event handled by a
/// [FocusOnKeyCallback].
enum KeyEventResult 
  /// The key event has been handled, and the event should not be propagated to
  /// other key event handlers.
  handled,
  /// The key event has not been handled, and the event should continue to be
  /// propagated to other key event handlers, even non-Flutter ones.
  ignored,
  /// The key event has not been handled, but the key event should not be
  /// propagated to other key event handlers.
  ///
  /// It will be returned to the platform embedding to be propagated to text
  /// fields and non-Flutter key event handlers on the platform.
  skipRemainingHandlers,