Qt 5, get the mouse position in a screen

Question

First of all, I\'d like to mention that I found that related post How to get the mouse position on the screen in Qt? but it \"just didn\'t work\" for me. I made some tests,

Answer 1

Sice it seems that it can't be done with Qt (at least with my system configuration, and it seems that also in Windows) I decided to use the libX11 to make that implementation, which works like charm.

It's not an ideal solution because I wanted to only use Qt, but it works.

Answer 2

This may seem like a trivial solution, but on my KDE it works (I ran into the same problems originally). If you want to determine the local mouse coordinates with respect to a widget (this will be in device pixels and relative to the top left corner of the widget I believe) you can use

QWidget::mapFromGlobal(QCursor::pos());

i.e. call this->mapFromGlobal.

Answer 3

This may work for you? It did for me

QDesktopWidget *widget = QApplication::desktop(); QPosition globalCursorPosition = widget->cursor().pos();

Answer 4

That's really weird. As a workaround, you could try this:

QPoint globalCursorPos = QCursor::pos();
int mouseScreen = qApp->desktop()->screenNumber(globalCursorPos);

Now you know which screen the cursor is in. Then you could find the cursor position within that screen doing this:

QRect mouseScreenGeometry = qApp->desktop()->screen(mouseScreen)->geometry();
QPoint localCursorPos = globalCursorPos - mouseScreenGeometry.topLeft();

Answer 5

To figure out on which screen you are, you can iterate throught QGuiApplication::screens() and check whether the cursor fits in the geometry of the screen.

Here is a more complex example to compute the native cursor position (note the additional work needed to work with High DPI screens):

QPoint getNativeCursorPosition()
{
    QPoint pos = cursorPosToNative(QCursor::pos());

    // Cursor positions from Qt are calculated in a strange way, the offset to
    // the origin of the current screen is in device-independent pixels while
    // the origin itself is native!

    for (QScreen *screen : QGuiApplication::screens()) {
        QRect screenRect = screen->geometry();
        if (screenRect.contains(pos)) {
            QPoint origin = screenRect.topLeft();
            return origin + (pos - origin) * screen->devicePixelRatio();
        }
    }

    // should not happen, but try to find a good fallback.
    return pos * qApp->devicePixelRatio();
}

Answer 6

With QML you can use the properties of the Screen QML Type:

Screen.virtualX : The x coordinate of the screen within the virtual desktop.

Screen.virtualY : The y coordinate of the screen within the virtual desktop.

import QtQuick 2.6
import QtQuick.Window 2.2

console.log("Pos x : " + Screen.virtualX )
console.log("Pos y : " + Screen.virtualY )

This work with single screen as well multi-monitor systems.