Environment: Qt 5.1 OSX 10.7.5
I am showing a contextMenu when a Qt::RightButton event is received.
Issue: It works fine except that the initial display is very slow and can take 3-5 seconds to display the menu. Any subsequent displays are immediate. The delay is long enough so that the user can think nothing is happening.
Question: Is there any way to preload or otherwise speed up the initial display of the contextMenu?
I've tried initializing it in my class constructor:
contextMenu = new QMenu(this);
QAction *saveAction=contextMenu->addAction("Save");
connect(saveAction,SIGNAL(triggered()),this,SLOT(saveSlot()));
I've tried declaring it as a pointer and as a... (not pointer? ;-)
QMenu *contextMenu;
This is the mousePressEvent that executes to show the contextMenu.
void RPImageLabel::mousePressEvent(QMouseEvent *event)
{
if (!imageRect.contains(event->pos())) return;
origin = event->pos();
this->setFocus();
if (event->button()==Qt::RightButton){
if (selectionRect.contains(origin))
// contextMenu.exec(this->mapToGlobal(origin));
contextMenu->exec(this->mapToGlobal(origin));
} else {
selectionStarted=true;
selectionRect.setTopLeft(origin);
selectionRect.setBottomRight(origin);
if (rubberBand->isHidden()){
rubberBand->setGeometry(QRect(origin, origin));
rubberBand->show();
repaint();
}
}
}
Ok, I solved this by changing the contextMenuPolicy from DefaultContextMenu to ActionsContextMenu for the widget in Qt Creator.
I'm new to Qt so just guessing here but perhaps this uses a Qt contextMenu instead of the OSX menu? In any event, it displays immediately now. However it does throw an alert on certain conditions:
QNSView mouseDragged:
Internal mouse button tracking invalid (missing Qt::LeftButton)
Not clear what is going on but I see that there has been a bug report filed which may be related.
Related
I'm running a Qt 5.9.4 app with QWebView on a touch linux device displaying HTML webpages.
When users pinch their fingers on the screen, they zoom into the webpage. I want to disable that behaviour, because all the webpages should be 100% fullscreen.
I could temporarily disable it in the webpages (since I own their code) by adding user-scalable=no to the viewport, but that wont work in the long run because not every webpage will have that.
I tried to use eventFilter on different elements of my app, but couldn't get any Gesture or even Mouse event to catch.
This is how I create my webview (in a QDialog):
void Dialog::createWebView() {
view = new QWebEngineView(this);
profile = new QWebEngineProfile();
page = new QWeEnginePage(profile);
view->setPage(page);
view->setUrl(QUrl(path));
}
This is my eventFilter class:
EvFilter::EvFilter(QObject *parent) : QObject(parent)
{
}
bool EvFilter::eventFilter(QObject *obj, QEvent *event)
{
qDebug() << event->type() << "\n";
return QObject::eventFilter(obj, event);
}
I have tried doing
EvFilter* evf = new EvFilter();
view->installEventFilter(evf);
And also on every other element (profile, page, dialog) but couldn't seem to get any events corresponding to mouse or gesture.
What am I doing wrong? How could I prevent that behaviour in the entire webview?
After adding the event listener to the QApplication object, I can detect TouchBegin, TouchUpdate, TouchCancel and TouchEnd events, but nothing else (no Gesture event). I dont know how could I detect if the touchevent is the zoom gesture.
I think you could use this on the Dialog (didn't test it). I had some other widget showing a QML QtWebView and what I did to prevent the widget's children to get Pinch Gestures is:
this->grabGesture(Qt::PinchGesture, Qt::DontStartGestureOnChildren);
This prevents the underlying widget from receiving the PinchGesture, so that you can handle it yourself.
I have implemented a clickable Frame in Xamarin.Forms 2.3.4 with a custom FrameRenderer that set Clickable (and LongPressable FWIW) to true, subscribed the respective events and set the FrameRenderers foreground
TypedValue typedValue = new TypedValue();
this.Context.Theme.ResolveAttribute(Android.Resource.Attribute.SelectableItemBackground, typedValue, true);
this.Foreground = this.Resources.GetDrawable(typedValue.ResourceId, this.Context.Theme);
to achieve Material motion (ripple touch).
After updating to XF 2.5 (most likely as of 2.3.5, since fast renderers have been introduced with that release) my touch events have ceased to work. My custom renderer is assigned correctly, so are the Clickable and LongPressable properties, but nothing happens. Partially I have been able to work around the issue - at least for the moment - by subscribing to FrameRenderer.Touch and call OnClick from that event handler. This renders the app usable, but unfortunately lacks the visual feedback in form of the ripple touch effect.
Is there any way I can restore the original behavior? Is there any way to implement a clickable frame with ripple touch in XF 2.5?
With the help of this answer I have figured out a solution. Here's a draft of it:
First of all I store a local reference to my RippleDrawable (see documentation)
private void SetMaterialMotion()
{
TypedValue typedValue = new TypedValue();
this.Context.Theme.ResolveAttribute(Android.Resource.Attribute.SelectableItemBackground, typedValue, true);
this.Foreground = this.Resources.GetDrawable(typedValue.ResourceId, this.Context.Theme);
this._layerDrawable = this.Foreground as RippleDrawable;
}
then I have to subscribe to the Touch event
private void SubscribeClickEvent()
{
if (this.ClickableFrame.IsClickable)
{
this.Touch += ClickableFrameRenderer_Touch;
}
}
In my ClickableFrameRenderer_Touch I set the Pressed property and the hotspot of the RippleDrawable
private void ClickableFrameRenderer_Touch(object sender, TouchEventArgs e)
{
if(e.Event.Action == Android.Views.MotionEventActions.Down)
{
this.Pressed = true;
}
if(e.Event.Action == Android.Views.MotionEventActions.Up)
{
this._layerDrawable.SetHotspot(e.Event.GetX(), e.Event.GetY());
this.Pressed = false;
}
}
This will show the ripple touch motion (more or less) as expected. Of course this does not handle long presses, yet, but I'm on a way.
Anyway, this is not a solution I like very much. I still think that there has to be a supported way on making FastRenderers.FrameRenderer clickable. If anyone knows it: Please share your knowledge.
I have pretty specific situation. I want to place a QAction into QToolbar and reach following behaviour:
Checkable QAction with icon.
Classic arrow on the right side which is used for showing menu
By pressing this arrow my QDialog should appears on screen instead of QMenu-like one
Now I'm a bit confused with implementing all this things together.
For now I've created QAction added it to toolbar and also created an empty QMenubecause I didn't get the idea of how to add the "dropdown" arrow another way.
So, I also connected my slot to QMenu aboutToShow() signal and now, I can create my dialog and exec() it just before QMenu shows. But here's the main problem appears: after I did everything with my dialog an click OK button QMenu trying to appear, but as it is empty it shows nothing and further actions become available only after I left-click somwhere to "close" this menu.
Is there any way to force QMenu not to show or can inherit from QMenu and reimplemnt its behaviour (I've tried to do such trick with exec() show() popup() methods of QMenu after subclassing from it, but none of them are being called when menu appears on the screen) ?
Here's the solution, which worked for me.
class QCustomMenu : public QMenu
{
Q_OBJECT
public:
QCustomMenu(QObject *parent = 0):QMenu(parent){};
};
In code:
QAction* myActionWithMenu = new QAction ( "ActionText", toolbar);
QCustomMenu* myMenu = new QCustomMenu(toolbar);
connect(myMenu, SIGNAL(aboutToShow()), this, SLOT(execMyMenu()));
execMyMenu() implementation:
void execMyMenu(){
m_activeMenu = (QCustomMenu*)sender(); // m_activeMenu -- private member of your head class, needs to point to active custom menu
QMyDialog* dlg = new QMyDialog();
// setup your dialog with needed information
dlg->exec();
// handle return information
m_myTimer = startTimer(10); // m_myTimer -- private member of your head(MainWindow or smth like that) class
}
Now we have to handle timerEvent and close our menu:
void MyHeadClass::timerEvent(QTimerEvent *event)
{
// Check if it is our "empty"-menu timer
if ( event->timerId()==m_myTimer )
{
m_activeMenu->close(); // closing empty menu
killTimer(m_myTimer); // deactivating timer
m_myTimer = 0; // seting timer identifier to zero
m_activeMenu = NULL; // as well as active menu pointer to NULL
}
}
It works great on every platform and does what I wanted.
Hope, this would help someone. I've spent week trying to find this solution.
I would simply like to catch the mouseRelease event when a user drags an item from a QTableView and releases the left button.
I want to highlight possible dropping zones in my app, like changing the background of a widget.
I start by detecting the drag-start by re-implementing:
void LibraryTableView::startDrag( Qt::DropActions supportedActions )
{
m_dragReleased = false;
emit dragStart();
QTableView::startDrag(supportedActions);
}
and emitting my own signal.
Now that the dropzone has changed, I need to catch the release event to redraw the dropzone as before whether the drag and drop succeded or not !
I tried different models, reimplementing the 4 mouse events and eventFilter, but the Mouse Release Event is never catched.
Here is my code:
void LibraryTableView::mouseDoubleClickEvent( QMouseEvent* event )
{
QTableView::mouseDoubleClickEvent(event);
}
void LibraryTableView::mouseMoveEvent( QMouseEvent* event )
{
qDebug() << "move";
QTableView::mouseMoveEvent(event);
}
void LibraryTableView::mousePressEvent( QMouseEvent* event )
{
qDebug() << "press";
QTableView::mousePressEvent(event);
}
void LibraryTableView::mouseReleaseEvent( QMouseEvent* event )
{
qDebug() << "real"; // Never called when drag ends ...
QTableView::mouseReleaseEvent(event);
}
So, it is a bug ?
If you know a trick, it would help me a lot.
Thanks !
Edit: I cannot reimplement dropEvent for every widget in my application, if the user drags and drop an element in another application, I still want to catch the release event ...
As said above it's been 3 years but thank to the last answer I found an even easier solution for this problem.
void LibraryTableView::startDrag( Qt::DropActions supportedActions )
{
m_dragReleased = false;
emit dragStart();
QTableView::startDrag(supportedActions);
//CODE HERE WILL BE EXECUTED ONLY WHEN THE MOUSE BUTTON HAS
//BEEN RELEASED SO YOU CAN DO THE FOLLOWING
emit dragStop();
}
Three years since this question was asked and this Qt problem still exists in Qt 5.4. Lately I had the same problem: Drops outside the application and no MouseReleaseEvent. The solution is simple and not really a trick:
The mousePressEvent, which starts the drag&drop looks like this (simplified):
void DragNDropListView::mousePressEvent(QMouseEvent *event){
....
QDrag *drag = new QDrag(this);
QMimeData *mimeData = new QMimeData;
mimeData->setData("application/x-xxxxxx", QByteArray());
drag->setMimeData(mimeData);
drag->exec();
// The d&d ended here. Inside the widget where the drag
// started, a mouseReleaseEvent would have been fired.
// Outside this widget not.
// drag->mimeData() is here still available.
}
}
}
The trick is simple: drag->exec() starts its own event loop, which is exited when the mouse button is released. The mouse position after drag->exec(); can be determined with QCursor.
For QTableView you have to reimplement three function for dnd support:
void dragEnterEvent ( QDragEnterEvent * event ) - in this function the mouse enters the widget
void QAbstractItemView::dragMoveEvent ( QDragMoveEvent * event ) - in this function you can update your drop zone highlighting
void QAbstractItemView::dropEvent ( QDropEvent * event ) - in this function you decide whether to accept the event
I encountered a similar issue and was not happy to find out that the MouseReleaseEvent was not getting fired at the end of a drag.
I just used the DragLeaveEvent and toggled my variables off, as I would have done in the MouseReleaseEvent. If user dragged off the app, and then back on, those previously toggled off variables would get re-enabled in the DragMoveEvent (assuming it is accepted).
That was my trick, at least. Hope it helps.
In my MainWindow, I have a push button and a menu bar item whose signals are both connected to the same slot. In the slot function, I have written:
mainWindow->setCursor(QCursor(Qt::WaitCursor));
This works as expected when the slot function is invoked via the button; however, when the same function is invoked from the menu, the wait cursor doesn't appear. Any idea why?
I also considered using QApplication::setOverrideCursor; however, that causes other problems.
Any recommendations? Thanks!
(I am using Qt 4.7 and doing my development on Windows 7 using Qt Creator with the default MinGW compiler.)
Here's more detail.
in MainWindow constructor: this->setCursor(Qt::CrossCursor);
signal/slot connections:
QObject::connect(button, SIGNAL(clicked()), MainWindow, SLOT(showMessageBox()));
QObject::connect(action, SIGNAL(triggered()), MainWindow, SLOT(showMessageBox()));
showMessageBox function:
void MainWindow::showMessageBox()
{
this->setCursor(Qt::WaitCursor);
// display wait cursor briefly before showing message box
for (int i = 0; i < 1<<30; ) {++i;}
QMessageBox msgBox;
msgBox.setText("Hello!");
msgBox.setStandardButtons(QMessageBox::Ok);
msgBox.setCursor(Qt::PointingHandCursor);
msgBox.exec();
this->setCursor(Qt::CrossCursor);
}
When showMessageBox is invoked with 'button', the wait cursor is displayed as expected.
When showMessageBox is invoked through 'action', the wait cursor does not appear; instead the cursor changes from Qt::CrossCursor to a Qt::ArrowCursor as soon as the user selects the 'action' menu item, and then changes to Qt::PointingHandCursor once the message box opens. The wait cursor never appears.
Your code is synchronous and uses a delay loop. When you're in the delay loop, there's no way for any Qt code to execute. A cursor change requires the event loop to be spinning -- so it appears from the symptoms you give.
Here's how to do it correctly -- remember, if you use delays/sleeps and other blocking calls in your GUI code, your users will hate you, and rightly so. Using exec() in message/dialog boxes is also bad style. Your application is asynchronous, code it so. Make sure your slots are declared as such (in the protected slots: section of MainWindow declaration).
void MainWindow::showMessageBox()
{
this->setCursor(Qt::WaitCursor);
QTimer::singleSlot(200, this, SLOT(slot1()); // fire slot1 after 200ms
}
void MainWindow::slot1()
{
QMessageBox * msgBox = new QMessageBox(this);
msgBox->setText("Hello!");
msgBox->setStandardButtons(QMessageBox::Ok);
msgBox->setCursor(Qt::PointingHandCursor);
msgBox->show();
connect(msgBox, buttonClicked(QAbstractButton*), SLOT(slot2(QAbstractButton*)));
}
void MainWindow::slot2(QAbstractButton* button)
{
// a button was clicked on the message box
this->setCursor(Qt::CrossCursor);
}