How to directly detect the window position? - c++

Question

I'm coding in c++ with Qt creator. I can get all windows on the screen but I would like to detect their movement directly. Is there any way to detect the movement thanks to a signal emitted by the window ?

Answer 1

You can try creating a QWindow from the target window and then wrap it in a QWidget using QWidget::createWindowContainer().
You can have a look at this QTBUG thread : https://bugreports.qt.io/browse/QTBUG-40320
It needs some effort to make it work properly. The captured window doesn't keep its initial dimensions, and releasing the window behave weirdly. Read the last QTBUG comments to find an improvement.
I added an event filter to this code to capture the window position in real time. But that might be unsatisfying.
class EventFilter : public QObject
{
Q_OBJECT
public:
EventFilter(){}
virtual ~EventFilter(){}
protected:
bool eventFilter(QObject *obj, QEvent *event);
} ;
bool EventFilter::eventFilter(QObject *obj, QEvent *event)
{
qDebug() << event->type() ;
if (event->type() == QEvent::Move) {
QMoveEvent *moveEvent = static_cast<QMoveEvent *>(event);
qDebug() << "position" << moveEvent->pos() ;
return true;
} else {
// standard event processing
return QObject::eventFilter(obj, event);
}
}
I removed part 3 from the QTBUG snippet and installed the event handler on the inner widget. You can also remove the timers.
// From https://bugreports.qt.io/browse/QTBUG-40320
int main(int argc, char *argv[])
{
// Windows: Find HWND by window title
WId id = (WId)FindWindow(NULL, L"Calculator");
if (!id)
return -1;
QApplication a(argc, argv);
// Optional
QTimer t;
t.start(2500);
// Part 1
QWindow* window = QWindow::fromWinId(id);
window->show();
window->requestActivate();
// Optional
QObject::connect(&t, &QTimer::timeout, [=]
{
qDebug() << "=== Inner QWindow ===";
qDebug() << "Geometry:" << window->geometry();
qDebug() << "Active?:" << window->isActive();
qDebug() << "Flags:" << window->flags();
});
// Part 2
QWidget* widget = QWidget::createWindowContainer(window);
widget->show();
// Optional
QObject::connect(&t, &QTimer::timeout, [=]
{
qDebug() << "=== Outer QWidget ===";
qDebug() << "Geometry:" << widget->geometry();
qDebug() << "Active?" << widget->isActiveWindow();
qDebug() << "Flags:" << widget->windowFlags();
});
// Realtime position
EventFilter filter ;
widget->installEventFilter( &filter ) ;
return a.exec();
}
Output:
=== Inner QWindow ===
Geometry: QRect(0,0 640x480)
Active?: true
Flags: QFlags<Qt::WindowType>(ForeignWindow)
=== Outer QWidget ===
Geometry: QRect(2489,29 640x480)
Active? true
Flags: QFlags<Qt::WindowType>(Window|WindowTitleHint|WindowSystemMenuHint|WindowMinMaxButtonsHint|WindowCloseButtonHint)
QEvent::Type(Move)
position QPoint(2484,29)
QEvent::Type(Move)
position QPoint(2481,30)
QEvent::Type(Move)
position QPoint(2478,31)
QEvent::Type(Move)
position QPoint(2474,31)
See also http://blog.qt.io/blog/2013/02/19/introducing-qwidgetcreatewindowcontainer/