The below code doesn't detect print_screen key for me.
void MainWindow::keyPressEvent(QKeyEvent *event)
{
if (Qt::Key_Print == event->key())
qDebug() << "Print Screen pressed";
Related
Ok, so I implemented the function following function:
CommandInput is a class which inherits the class QComboBox.
void CommandInput::dragEnterEvent(QDragEnterEvent *event)
{
qDebug() << "Proposed drop " << event->mimeData()->formats();
event->acceptProposedAction();
}
and it is working fine.
But the problem is my following function is not working , in fact when I click mouse button, nothing gets printed, Why is that?
void CommandInput::mousePressEvent(QMouseEvent *e)
{
qDebug()<<"X IS"<<e->pos().x();
}
Sample:
Label::Label(QLabel *parent) :
QLabel(parent)
{
this->show();
this->resize(200, 200);
}
void Label::mousePressEvent(QMouseEvent *event)
{
this->resize(300, 300);
}
Expected result： when i press label by touching, the label will become bigger.
Actual result： when i release or move my finger, it become bigger.
Its looks like the mousePressEvent is not detected.
BTW QML also have same problem for MouseArea onPressed
Thanks for answering, i tried to add this:
bool Label::event(QEvent *e)
{
if(e->type() == QEvent::TouchBegin)
qDebug() << "TouchBegin";
if(e->type() == QEvent::TouchCancel)
qDebug() << "TouchCancel";
if(e->type() == QEvent::TouchEnd)
qDebug() << "TouchEnd";
if(e->type() == QEvent::TouchUpdate)
qDebug() << "TouchUpdate";
return e->isAccepted();
}
But the TouchBegin event still not be detected when i pressed.
I grabGesture()ed one of my buttons:
buttons[0]->grabGesture(Qt::TapAndHoldGesture);
in the constructor, and declared:
bool event(QEvent *event);
in protected slots, and implemented it like this:
bool MyClass::event(QEvent *event)
{
if (event->type() == QEvent::Gesture){
QGestureEvent *gestevent = static_cast<QGestureEvent *>(event);
if (QGesture *gest = gestevent->gesture(Qt::TapAndHoldGesture)){
QTapAndHoldGesture *tapgest = static_cast<QTapAndHoldGesture *>(gestevent->gesture(Qt::TapAndHoldGesture));
cout << "grabbed a gesture event" << endl;
}
return true;
}
cout << "not a gesture event" << endl;
return QWidget::event(event);
}
and I keep getting "not a gesture event" printed to screen however I press (normal press / long press / ... )
What I'm trying to do is a long key press (from the keyboard)
It's said in the Qt Documentation:
A gesture could be a particular movement of a mouse, a touch screen
action, or a series of events from some other source. The nature of
the input, the interpretation of the gesture and the action taken are
the choice of the developer.
So I suppose also a keyboard can trigger QGesture events.
If the class handling the grap (MyClass) event is not the class where the gesture is detected on (QPushButton assuming buttons[0] is a QPushButton), then you need and event filter:
buttons[0]->grabGesture(Qt::TapAndHoldGesture);
buttons[0]->installEventFilter( myClass ); // myClass being a MyClass instance
Now, myClass object will be forwarded all events from buttons[0], this is done using QObject::eventFilter virtual function:
bool MyClass::eventFilter(QObject *obj, QEvent *event)
{
if ( event->type() == QEvent::Gesture && obj == buttons[0] )
{
QGestureEvent *gestevent = static_cast<QGestureEvent *>(event);
if (QGesture *gest = gestevent->gesture(Qt::TapAndHoldGesture)){
QTapAndHoldGesture *tapgest = static_cast<QTapAndHoldGesture *>(gestevent->gesture(Qt::TapAndHoldGesture));
cout << "grabbed a gesture event" << endl;
return true;
}
}
// standard event processing
return Parent::eventFilter(obj, event); // Parent being MyClass parent type, maybe QDialog or QWidget
}
I am intended to implement an QListView, which will be showing a frame when I will double press my mousebutton on each delegate. With my very basic programming skill I cann't do it. Here below is my code:
void MainWindow::eventFilter(QObject *obj, QEvent *event)
{
if (obj == ui->listView->viewport() && event->type() == QEvent::MouseButtonDblClick)
{
int row = getListViewRow();
qDebug() << "Double Clicked on Row: " << row << endl;
mFrame->setGeometry(700,500,150,150);
mFrame->show(); }}
Inside my constructor I also have added this below line:
qApp->installEventFilter(this);
So please correct me to achieve the goal. Thanks.
The solution is quite simple: If you install an event-filter, you need to install it on the object whos events you want to filter:
ui->listView->viewport()->installEventFilter(this);
I have a sever client application and in the beginning client loads data from server. I have a dialog showing status of getting data from server (has progress bar). But when I call the function the dialog appears with no contents in it with white background and suddenly changes to completed status.
void SystemScreen::loadServerData()
{
qDebug() << Q_FUNC_INFO << "Invoked";
if (NULL != mpDataManagerDlg)
{
qDebug() << Q_FUNC_INFO << "show progres screen";
mpDataManagerDlg->showScreen();
}
loadData();
qDebug() << Q_FUNC_INFO << "Exits";
}
void SystemScreen::loadData()
{
qDebug() << Q_FUNC_INFO << "Invoked";
if (NULL != mpDataManager)
{
mpDataManager->loadDataFromServer();
}
qDebug() << Q_FUNC_INFO << "Exits";
}
I feel that dialog is displayed only after loadData() function is completed. Is there any alternative to do this?
I used a timer to start
QTimer::singleShot(100, this, SLOT(loadData()));
But then I have some trouble in getting data. ie data is empty if I read suddenly.
EDIT:
void DataManagerDialog::setDefault()
{
qDebug() << Q_FUNC_INFO << "Invoked";
setProgressBar(0);
setProgressBarColor(false);
ui->deptFailButton->hide();
ui->deptOkButton->hide();
ui->deptLabel->setStyleSheet("color:gray");
ui->subGroupFailButton->hide();
ui->subGroupOkButton->hide();
ui->subGroupLabel->setStyleSheet("color:gray");
ui->itemFailButton->hide();
ui->itemOkButton->hide();
ui->itemLabel->setStyleSheet("color:gray");
ui->salesBtnFailButton->hide();
ui->salesBtnOkButton->hide();
ui->salesBtnLabel->setStyleSheet("color:gray");
qDebug() << Q_FUNC_INFO << "Exits";
}
void DataManagerDialog::alignCenter()
{
qDebug() << Q_FUNC_INFO << "Invoked";
QWidget *par = parentWidget();
if (par)
{
int x = width()/2;
int y = height()/2;
QPoint mid(mapToGlobal(QPoint(x, y)));
int px = par->width()/2;
int py = par->height()/2;
QPoint parMid(mapToGlobal(QPoint(px, py)));
move(parMid.x()-mid.x(), parMid.y()-mid.y());
}
qDebug() << Q_FUNC_INFO << "Exits";
}
void DataManagerDialog::showScreen()
{
setDefault();
alignCenter();
show();
}
You probably do not enter the event loop.
Try to call QCoreApplication::processEvents() from time to time in mpDataManager->loadDataFromServer() to update the GUI.
From the processEvents documentation :
You can call this function occasionally when your program is busy performing a long operation (e.g. copying a file).
Edit added after getting feedback from the comments
A better approach would be to send signals in your loadDataFromServer() method with the status information and have a slot listen to the signal and update the GUI.
Here a prototype illustrating the idea :
void mpDataManagerDlg::loadDataFromServer() {
while(true) {
// do some work
int progress = // some value
emit updateDialogSignal(progress);
}
}
// in your dialog class
public slots:
void DataManagerDialog::updateDialog(int progress) {
// update gui
}
More about signals and slots can be found here.