如何使用Qt聚焦menuBar() [英] How to focus menuBar() with Qt
问题描述
我有一个有效的应用程序.我向带有某些菜单的主窗口添加了menuBar().然后,我将其隐藏以释放屏幕空间.我在下面编写了代码,以便当用户按ALT键时,菜单栏在隐藏时会出现,在显示时会隐藏.
I have a working application. I added a menuBar() to the main window with some menus. Then, I hid it to free screen space. I wrote the code below so that when user presses ALT key, the menu bar appears if it's hidden, and it hides if it's displayed.
void MainWindow::keyPressEvent( QKeyEvent *k ) {
if(k->modifiers() & Qt::AltModifier) {
menuBar()->setHidden(!menuBar()->isHidden());
if(menuBar()->hasFocus()) {
QMessageBox::information(this, "Info", "Focus !");
}
}
}
如您所见,我还添加了一个QMessageBox来查看menuBar何时具有焦点.并且此框仅出现一半的时间.它是这样的:
As you can see, I also added a QMessageBox to see when the menuBar has the focus. And this box appears only half of the time. It goes like this :
- 应用程序已启动,菜单栏已隐藏
- 我按ALT,显示菜单栏,没有消息框,没有焦点
- 我按ALT键,菜单栏隐藏了
- 我按ALT,显示菜单栏,消息框,焦点
- 我按ALT键,菜单栏隐藏了
- 我按ALT,显示菜单栏,没有消息框,没有焦点
- 我按ALT键,菜单栏隐藏了
- 我按ALT,显示菜单栏,消息框,焦点
- 等
如何确保显示menuBar时始终具有焦点?
How to make sure when the menuBar is displayed, it always has focus ?
推荐答案
我想做同样的事情.我的解决方案,完整的示例,作为要点:
I wanted to do the same thing. My solution, complete example, as a gist:
https://gist.github.com/xim/ee56564f425151ea2fa70f730d644873
针对Qt 5.9.4进行了测试.
Tested against Qt 5.9.4.
由于它包含许多其他垃圾,因此是一个最小的示例:
As it contains a lot of other junk, a minimal example:
class AutoHidingMenuBar : public QMenuBar {
Q_OBJECT
public:
AutoHidingMenuBar() : QMenuBar() {
setMaximumHeight(0);
connect(qApp, &QApplication::focusChanged, this, &AutoHidingMenuBar::focusChanged);
}
private slots:
void focusChanged(QWidget *from, QWidget *to) {
bool inFocus = hasFocus() || isAncestorOf(focus) || hasFocusedChild();
if (inFocus && maximumHeight() == 0) {
auto action = activeAction();
setMaximumHeight(100);
if (action) {
// XXX This is a bit of a hack. We could do
// QCoreApplication::processEvents();
// setActiveAction(action);
// with almost the same effect, but then we *open* the first menu on single alt press...
auto evt = new QMouseEvent(QEvent::MouseMove, actionGeometry(action).center(), Qt::NoButton, Qt::NoButton, Qt::NoModifier);
QCoreApplication::postEvent(this, evt);
}
} else if (!inFocus && maximumHeight() != 0)) {
setMaximumHeight(0);
}
}
private:
bool hasFocusedChild() {
QObjectList queue{children()};
while (!queue.empty()) {
auto child = queue.takeFirst();
auto widget = dynamic_cast<QWidget *>(child);
if (widget && widget->hasFocus())
return true;
queue.append(child->children());
}
return false;
}
};
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