Tracking mouse coordinates in Qt

Question

Let's say I have a widget in the main window and want to track the mouse position ONLY on widgets: this means that the lower left corner of the widget must be local (0, 0).

Q: How can I do this?

ps The functions below are listed below.

widget->mapFromGlobal(QCursor::pos()).x(); QCursor::pos()).x(); event->x(); 

Answer 1

I’m afraid you won’t be satisfied with your requirement “the bottom left should be (0,0). In the Qt coordinate systems (0,0), the top left. If you can accept this. The following code ...

 setMouseTracking(true); // Eg set in your constructor of your widget. // Implement in your widget void MainWindow::mouseMoveEvent(QMouseEvent *event){ qDebug() << event->pos(); } 

... will give you the coordinates of the mouse pointer in your widget.

Answer 2

If all you want to do is tell the mouse position in coordinates, as if the lower left corner of the widget was (0,0), and Y increased as you climb, then the code below does this. I think that the reason for the desire for such a code is wrong, since the coordinates of everything else in the specified widget do not work in this way. So why do you want it, I can’t understand, but here you go.

 #include <QApplication> #include <QMouseEvent> #include <QTransform> #include <QLabel> class Window : public QLabel { public: Window(QWidget *parent = 0, Qt::WindowFlags f = 0) : QLabel(parent, f) { setMouseTracking(true); setMinimumSize(100, 100); } void mouseMoveEvent(QMouseEvent *ev) { // vvv That where the magic happens QTransform t; t.scale(1, -1); t.translate(0, -height()+1); QPoint pos = ev->pos() * t; // ^^^ setText(QString("%1, %2").arg(pos.x()).arg(pos.y())); } }; int main(int argc, char *argv[]) { QApplication a(argc, argv); Window w; w.show(); return a.exec(); }