A user can step through the widgets of QtGUI via key "Tab" or via arrow keys "<-" and "->".
Does anybody know how to disable the arrow keys for this purpose? I need the arrow keys for something else.
You would need to reimplement the corresponding event in your own QWidget subclass as follows:
bool MyWidget::keyPressEvent(QKeyEvent *keyEvent)
{
if (keyEvent->key() == Qt::Key_Left || keyEvent->key() == Qt::Key_Right) {
// Do nothing
} else {
QWidget::keyPressEvent(keyEvent);
}
}
Just reimplement event() or keyPressEvent() / keyReleaseEvent() of main window. In reimplemented methods you can place your desired actions.
I may use QAction for this purpose. So you wont need subclassing.
QTabBar *tabBar;
........................
QAction* pLeftArrowAction = new QAction(this);
pLeftArrowAction->setShortcut(Qt::Key_Left);
QAction* pRightArrowAction = new QAction(this);
pRightArrowAction->setShortcut(Qt::Key_Right);
tabBar->addActions(QList<QAction*>() << pLeftArrowAction << pRightArrowAction);
Related
I have QGraphicsView, which has many QGraphicsItem. I am trying to create a right click menu on these QGraphicsItem. Right click menu has multiple options. But only 1st option works. It means, if I click on 2nd option, it does not work. If I change the sequence ( means 1st one will go to 2nd position, and 2nd one will come to 1st position ) then still 2nd one will not work.
bool myClass::eventFilter(QObject *watched, QEvent *event)
{
switch(event->type())
{
case QEvent::ContextMenu:
{
foreach(QGraphicsItem* pItem, _scene->items())
{
if(pItem->isUnderMouse())
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*> (event);
menu = new QMenu(this);
myMenu = menu->addMenu("Copy");
myMenu ->addAction(Name);
myMenu ->addAction(Address);
if(Name == menu->exec(mouseEvent->globalPos()))
{
// logic
}
if(Address == menu->exec(mouseEvent->globalPos()))
{
// logic
}
}
}
}
}
Always works only 1st mouse right click option. Why is so ?
The usual way to do something like this is to override the QGraphicsItem::mouseReleaseEvent() or QGraphicsItem::mousePressEvent() function of your item class.
This way, you won't have to do anything (no looping, etc...), it is already handled by the event loop.
Here you can find a simple example:
void MyItem::mouseReleaseEvent(QGraphicsSceneMouseEvent * event)
{
if(event->button() == Qt::RightButton)
{
QMenu my_menu;
// Build your QMenu the way you want
my_menu.addAction(my_first_action);
my_menu.addAction(my_second_action);
//...
my_menu.exec(event->globalPos());
}
}
From the Qt documentation:
Note that all signals are emitted as usual. If you connect a QAction to a slot and call the menu's exec(), you get the result both via the signal-slot connection and in the return value of exec().
You just need to QObject::connect() the QActions you added to the context menu to the proper slots (here goes the "logic") and the job is done.
If you prefer to check the returned value by yourself, you just have to get the returned QAction* once and for all (only one call to QMenu::exec()) and branch on it.
For example:
void MyItem::mouseReleaseEvent(QGraphicsSceneMouseEvent * event)
{
if(event->button() == Qt::RightButton)
{
QMenu my_menu;
// Build your QMenu the way you want
my_menu.addAction(my_first_action);
my_menu.addAction(my_second_action);
//...
QAction * triggered = my_menu.exec(event->globalPos());
if(triggered == my_first_action)
{
// Do something
}
else if(triggered == my_second_action)
{
// Do some other thing
}
//...
}
}
I would personnally prefer to stick with the signal-slot connections instead that manually handling the returned value, especially since each QAction is most likely to be already connected to its corresponding slot.
I have set a large menu in event filter on right click with 45-50 actions
inside and I find that when I right click the response to show the menu is slow
I did try the same code with 5 actions in the menu and the response was fine.
Is there something wrong with this way of coding on a contex menu ?
eventFilter
bool Editor::eventFilter(QObject *o, QEvent *e)
{
Q_UNUSED (o);
QGraphicsSceneMouseEvent *me = (QGraphicsSceneMouseEvent*) e;
switch ((int) e->type()){
case QEvent::GraphicsSceneMousePress:{
switch ((int) me->button()){
case Qt::RightButton:{
QGraphicsItem *item = itemAt(me->scenePos());
showContextMenu(item->scenePos().toPoint());
return true;
}
//more cases here//
}
break;
}
}
return QObject::eventFilter(o, e);
}
showContextMenu
void Editor::showContextMenu(const QPoint &pos)
{
QGraphicsItem *item =itemAt(pos);
// Create main effe menu
effeMenu= new QMenu("Menu");
QString menuStyle(
"QMenu {"
"border:10px };"
//more code here
);
effeMenu->setStyleSheet(menuStyle);
AmpMenu=effeMenu->addMenu(QIcon(":/effectImg/img/effePng/amp.png"),"Amp");
Amp1 =AmpMenu->addAction(QIcon(":/effectImg/img/effePng/amp.png"),"Amp 1");
Amp2 =AmpMenu->addAction(QIcon(":/effectImg/img/effePng/amp.png"),"Amp 2");
CabMenu=effeMenu->addMenu(QIcon(":/effectImg/img/effePng/cab.png"),"Cab");
Cab1 =CabMenu->addAction(QIcon(":/effectImg/img/effePng/cab.png"),"Cab 1");
Cab2 =CabMenu->addAction(QIcon(":/effectImg/img/effePng/cab.png"),"Cab 2");
.
.
.
.
//45 actions more
connect(effeMenu, &QMenu::triggered,this,[this,&item](QAction * k){
menuSelection(k,item);
});
Instead of creating a new QMenu each time you call showContextMenu you could make it a member of the class and build it once. On the other hand it is not necessary to use a signal, you could simply use the exec() method of QMenu:
*.h
class Editor: ...{
...
private:
QMenu effeMenu;
}
*.cpp
Editor::Editor(...){
effeMenu.setTitle("Menu");
QString menuStyle(
"QMenu {"
"border:10px };"
//more code here
);
effeMenu.setStyleSheet(menuStyle);
AmpMenu=effeMenu.addMenu(QIcon(":/effectImg/img/effePng/amp.png"),"Amp");
Amp1 =AmpMenu->addAction(QIcon(":/effectImg/img/effePng/amp.png"),"Amp 1");
Amp2 =AmpMenu->addAction(QIcon(":/effectImg/img/effePng/amp.png"),"Amp 2");
CabMenu=effeMenu.addMenu(QIcon(":/effectImg/img/effePng/cab.png"),"Cab");
Cab1 =CabMenu->addAction(QIcon(":/effectImg/img/effePng/cab.png"),"Cab 1");
Cab2 =CabMenu->addAction(QIcon(":/effectImg/img/effePng/cab.png"),"Cab 2");
...
}
void Editor::showContextMenu(const QPoint &pos){
QGraphicsItem *item =itemAt(pos);
QAction *action = menu.exec(pos);
menuSelection(action, item);
}
There are two things you can do to improve speed:
1 - itemAt(pos) is costly, and you are doing it twice, one in the event, and one in the showContextMenu. From what I could understand from your code you don't need the item in the event, just in the showMenu.
2 - The menu creation that you are doing is expensive: all the actions have pixmaps. this allocs memory for the QPixmap, loads, execute, dumps. Because you told us that you use around 40 actions (and really, that's too much for a menu), this can get costly.
My advice:
Create a class for your menu, create one instance of it, add a setter for the current QGraphicsObject that your menu will work on, and always use that one instance.
I'm developing a project in Qt. I have a QTreeWidget(filesTreeWidget) whith some file names and a button for creating a file. The Create button adds to the filesTreeWidget a new item(the item's text is "") who is edited for choosing a name. When I press ENTER, the filename is send through a socket to the server. The problem comes when I press ESC because the filename remains "" and is not send to the server. I tried to overwrite the keyPressEvent but is not working. Any ideas? I need to catch the ESC press event when I'm editing the item.
You can subclass QTreeWidget, and reimplement QTreeView::keyPressEvent like so:
void MyTreeWidget::keyPressEvent(QKeyEvent *event)
{
if (event->key() == Qt::Key_Escape)
{
// handle the key press, perhaps giving the item text a default value
event->accept();
}
else
{
QTreeView::keyPressEvent(event); // call the default implementation
}
}
There might be more elegant ways to achieve what you want, but this should be pretty easy. For example, if you really don't want to subclass, you can install an event filter, but I don't like doing that especially for "big" classes with lots of events because it's relatively expensive.
Implement keyPressEvent function as following:
void TestTreeWidget::keyPressEvent(QKeyEvent *event)
{
switch (event->key())
{
case Qt::Key_Escape:
{
escapeKeyPressEventHandler();
event->accept();
break;
}
default:
QTreeWidget::keyPressEvent(event);
}
}
TestTreeWidget::escapeKeyPressEventHandler()
{
// work with your QTreeWidgetItem here
}
I'm using QTreeView with selectionMode set to ExtendedSelection. I'd like to change the default behavior that clears selected items each time an arrow key is used to change the current item (focus).
Is it possible to set it up so that when I use an arrow key to navigate, the selection keeps and only the current item (focus) changes (in the same way as it works when using Ctrl+Arrow). I would basically need to swap the behavior of (Arrow vs. Ctrl+Arrow), or just us Ctrl+Arrow-like behavior even when Ctrl is not pressed.
Is that possible?
Thanks,
FipS
This is a good question, as the functions you need to use are a bit obscure. You're going to have to subclass QTreeView and override the keyPressEvent() function. This should get you on the right track:
class MyTree : public QTreeWidget
{
Q_OBJECT
protected:
void keyPressEvent( QKeyEvent *event )
{
if( event->key() == Qt::Key_Up )
{
selectionModel()->setCurrentIndex( indexAbove(currentIndex()), QItemSelectionModel::NoUpdate );
}
else if( event->key() == Qt::Key_Down )
{
selectionModel()->setCurrentIndex( indexBelow(currentIndex()), QItemSelectionModel::NoUpdate );
}
else
{
QTreeWidget::keyPressEvent( event );
}
}
};
void MainWindow::addRadioToUI()
{ int button_cunter=4;
while(!database.isEmpty())
{ button_cunter++;
QPushButton *one = new QPushButton("Play: "+name(get_r.getTrackId()));
one->setIcon(QIcon(":/images/play_button.png"));
one->setMaximumWidth(140);
one->setFlat(true);
QGroupBox* get_rGB = new QGroupBox("somethink");
QFormLayout* layout = new QFormLayout;
if(button_cunter%5 == 0){
layout->addWidget(one);
}
get_rGB->setLayout(layout);
scrollAreaWidgetContents->layout()->addWidget(get_rGB);
}
}
I have a few QPushButtons which are added automaticlly.
Is there a way to add "id attribute or sth else" to button and next know which button was clicked? I have different action for each button.
QApplication offers sender() which contains which object sent the signal. So you can do:
//slot, this could also be done in a switch
if(button[X] == QApplication::sender()){
doX();
}else if(button[Y] == QApplication::sender()){
doY();
}
http://doc.qt.io/qt-4.8/qobject.html#sender
QSignalMapper is pretty good for this type of thing.
You would define your slot like this for instance:
public slots:
void clicked(int buttonId); // or maybe trackId
Then add a QSignalMapper* member to your class and connect it to that slot:
signalMapper = new QSignalMapper(this);
connect(signalMapper, SIGNAL(mapped(int)),
this, SLOT(clicked(int)));
In the addRadioToUI, after creating your push button, do:
signalMapper.setMapping(one, button_cunter);
// or trackId if that's more practical
If all you need is a pointer to the object that triggered the signal though, you can use the static QOjbect::sender function in your slot to get a handle to that.
Use QButtonGroup. It takes id as a parameter when a button is added and provides the id to a slot when a button in the group is pressed.