使用 enaml 时如何获取关键事件？

Question

我一直在使用 enaml（0.6.8，目前 Canopy 可用）并成功创建了一些非常有用的实用程序应用程序。但是，我想拦截键盘事件以启用一些快速键盘快捷键，而不是在 UI 中重复单击按钮。

我该如何处理？我知道这将是特定于工具包（qt4）的，但无法真正弄清楚从哪里开始。我在 qt 中阅读了一些关于 event filters 的内容，这似乎是我想要的，但我不明白将 QApplication 等与 enaml 相关联的机制

Answer 1

目前不支持拦截原始键事件，除非您想通过foo.proxy.widget 直接使用工具包小部件（在 0.7+ 系列上；不再支持 0.6 系列）。但是，您可以使用支持由自定义操作名称（例如“Cut\tCtrl+C”和“Paste\tCtrl+V”）触发的加速键的 Actions 定义 MenuBar。

Answer 2

我创造了一种相当粗糙的方法来做到这一点。使用以下内容创建一个名为 key_event.py 的文件：

# -*- coding: utf-8 -*-
'''
Created on Jul 20, 2015
@author: jrm
'''
from atom.api import (Callable,Event, Value, Unicode, Bool, Instance,Typed, ForwardTyped, observe)
from enaml.core.declarative import d_
from enaml.widgets.control import Control, ProxyControl
from enaml.qt.qt_control import QtControl
from enaml.qt import QtCore

class ProxyKeyEvent(ProxyControl):
    declaration = ForwardTyped(lambda: KeyEvent)

    def set_enabled(self, enabled):
        raise NotImplementedError

class KeyEvent(Control):
    proxy = Typed(ProxyKeyEvent)

    key_code = d_(Value())
    key = d_(Unicode())
    enabled = d_(Bool(True))
    repeats = d_(Bool(True))

    pressed = d_(Event(),writable=False)
    released = d_(Event(),writable=False)

    @observe('enabled')
    def _update_proxy(self, change):
        """ An observer which sends state change to the proxy.
        """
        super(KeyEvent, self)._update_proxy(change)

class QtKeyEvent(QtControl, ProxyKeyEvent):
    _keyPressEvent = Callable() # Refs to original functions
    _keyReleaseEvent = Callable() # Refs to original functions
    widget = Instance(QtCore.QObject)

    def create_widget(self):
        self.widget = self.parent_widget()
    def init_widget(self):
        super(QtKeyEvent, self).init_widget()
        d = self.declaration
        widget = self.parent_widget()
        self._keyPressEvent = widget.keyPressEvent
        self._keyReleaseEvent = widget.keyPressEvent
        self.set_enabled(d.enabled)

    def set_enabled(self, enabled):
        widget = self.parent_widget()
        if enabled:
            widget.keyPressEvent = lambda event:self.on_key_press(event)
            widget.keyReleaseEvent = lambda event:self.on_key_release(event)
        else:
            # Restore original
            widget.keyPressEvent = self._keyPressEvent
            widget.keyReleaseEvent = self._keyReleaseEvent

    def on_key_press(self,event):
        try:
            if (self.declaration.key_code and event.key()==self.declaration.key_code) or \
                (self.declaration.key and self.declaration.key in event.text()):
                if not self.declaration.repeats and event.isAutoRepeat():
                    return
                self.declaration.pressed(event)
        finally:
            self._keyPressEvent(event)

    def on_key_release(self,event):
        try:
            if (self.declaration.key_code and event.key()==self.declaration.key_code) or \
                (self.declaration.key and self.declaration.key in event.text()):
                if not self.declaration.repeats and event.isAutoRepeat():
                    return
                self.declaration.released(event)
        finally:
            self._keyReleaseEvent(event)

def key_event_factory():
    return QtKeyEvent
# Inject the factory 
from enaml.qt.qt_factories import QT_FACTORIES
QT_FACTORIES['KeyEvent'] = key_event_factory

在您的 enaml 文件中导入 KeyEvent 并像这样使用：

WidgetToWatchKeys:
  KeyEvent:
    key_code = QtCore.Qt.Key.Key_Up
    pressed :: model.move_up()

  KeyEvent:
    key_code = QtCore.Qt.Key.Key_Left
    pressed :: model.move_left()

  KeyEvent:
    key = 'x'
    pressed :: model.fire()
  #: etc...

可能不是最好的方法，但它可以满足我的需求。