Screen.Size questions

carles.sole.grau

Hi everybody,
when developing in Qt QML there is an object called Screen that is useful to size some items (http://doc.qt.io/qt-5/qml-qtquick-window-screen.html). But there is something that I don't understand at all.

I have a One Plus X, its width specs are (https://oneplus.net/es/x/specs)
Width in physical PIXELS: 1080 pixels
Width in mm: 69 mm (so the screen a little bit less)

So when I run this part of code:

console.log("Width in pixels: " + Screen.width)
console.log("Pixel Ratio: " + Screen.devicePixelRatio )

It returns me

qml: Width in pixels: 360
qml: Pixel Ratio: 3

So I understant that Screen.width returns he width in logical pixels:

Device Pixel Ratio: The ratio between physical pixels and device-independent pixels for the screen.
So:

360 logical pixels = 1080 pyhisical pixels * 1 logical pixel/3 pyhisical pixels

And in documentation it is called that the property pixelDensity:
Pixel Density: The number of physical pixels per millimeter.
But if I check this:

console.log("Pixel Density: " + Screen.pixelDensity )

qml: Pixel Density: 5.786108689334496

It returns a density that NOT corresponds in the density of physical pixels because

**1080** physical pixels / **5.78** physical pixels/mm = 186.85 mm

And the width IS NOT 186.85, instead of that:

**360** logical pixels / **5.78** logical pixels/mm = 62,28 mm

That it match with the with of my device.

So... The pixel density documentation is not OK?

It would be: (The number of ~~physical~~ logical pixels per millimeter) ?

Thank you very much

? Offline

Hi! Looking at qquickscreen.cpp, it's not a documentation bug:

qreal QQuickScreenInfo::pixelDensity() const
{
    if (!m_screen)
        return 0.0;
    return m_screen->physicalDotsPerInch() / 25.4;
}

So it must be something else, maybe a bug in some driver or in the platform abstraction layer for your particular device. I'd recommend to file a bug, https://bugreports.qt.io.