QML on android does not fill the entire screen

tubbadu

I'm trying to write android apps in QML, so I followed the official guides, but I have this problem:
with this simple code:

import QtQuick
import QtQuick.Controls
import QtQuick.Layouts

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("hello world")

    Rectangle{
        color: "red"
        anchors.fill: parent
    }
}

I expected my entire screen to be covered by the application (except of course the bottom buttons and the top statusbar) but instead this is the result:

alt text

why is there that white line at the bottom? how can I cover it?
changing Window height and width or unspecifying those attributes doesn't change the result

thanks in advance!

TomZ

I can confirm this on one of my phones. An annoying white background, while the palette doesn't have any white in it.
My other Android phones with the exact same binary do not have this issue.

I'm thinking this is a bug in Qt.

tubbadu

@TomZ so this bug is device-dependent? may it be a wrong setting in AndroidManifest.xml that may mess up with some specific devices, perhaps with unusual screen size etc?

TomZ

Its a good question where it comes from. The actual resolution is quite different, but things like the aspect ratio is identical between the phones.
I'm not sure how a full screen image would not be full-screen..

Here the screenshots, notice he similarity with your screenshot. ps. this uses a ApplicationWindow QML for top-level.

See album at https://imgur.com/a/GEO5aay

tubbadu

That's really strange, I don't really know how to resolve or workaround this bug

JoeCFD

@tubbadu said in QML on android does not fill the entire screen:

import QtQuick
import QtQuick.Controls
import QtQuick.Layouts

Window {
width: 640
height: 480
visible: true
title: qsTr("hello world")
Rectangle{
    color: "red"
    anchors.fill: parent
}
}
can you try the following? My app has not border.

import QtQuick
import QtQuick.Controls
import QtQuick.Layouts

Window {
    visible: true
    visibility: Window.FullScreen
    title: qsTr("hello world")

    Rectangle{
        color: "red"
        anchors.fill: parent
    }
}

tubbadu

@JoeCFD said in QML on android does not fill the entire screen:

visibility: Window.FullScreen

yeah this allowed my app to be real fullscreen without showing that ugly while line! thank you!

this btw hides the system buttons and the top notification bar, which I'd like to see in my application. Until I'll find a fix I'll use this workaround, thanks you very much!

JoeCFD

@tubbadu for that you may try:

Window {
width: Screen.width
height: Screen.height
}

but remove visibility: Window.FullScreen

tubbadu

@JoeCFD sadly this didn't work :(
Window's height and width attributes seems to have no effect at all in android application, I can set them to 1 or 1000000 or do not set them at all, but nothing changes, always that white line

JoeCFD

@tubbadu sorry. I did it long ago and sort of forgot it wile I did not need it. Try

Window {
minimumWidth: Screen.width
minimumHeight: Screen.height
}

if it does not work, add

Window {
minimumWidth: Screen.width
minimumHeight: Screen.height
maximumWidth: Screen.width
maximumHeight: Screen.height
}

tubbadu

@JoeCFD nothing to do... always that awful white line :(

thanks for your efforts, I really appreciate!

JoeCFD

@tubbadu Just tested my app. I can see the bottom, but not the top bar. However, I can not see the white line.

ApplicationWindow {
minimumWidth: Screen.width
minimumHeight: Screen.height
}

Replace Window with ApplicationWindow

tubbadu

@JoeCFD said in QML on android does not fill the entire screen:

ApplicationWindow

still nothing...

JoeCFD

@tubbadu what are your qt version and android version?
Mine is Qt 5.15.2 and Android 12

tubbadu

@JoeCFD I'm using Qt 6.2 in android 10, I'll try to compile it in Qt 5 and see what will happen

JoeCFD

@tubbadu Maybe the latest Qt6.4 is better.

TomZ

I found a 3rd phone that has an even taller white line.

The reference to Screen.width etc did give me an idea.
I created a big empty app and just a label with those numbers printed in the center.

The fun result is that I got the low-res number. Not the actual number. (360 x 780 instead of 720x1560).
And I got the exact same number on both phones, including the one with the white.

So, next step. Show the size of my big empty app. It gives me 360x706 on the phone where I do not have a white bar.
The one with the white bar gives me 360x686.

So, concluding, the "Screen" part is irrelevant here as that is the 'fullscreen' size. Additionally, this is a problem that looks like it can not be solved from QML as we simply don't get the full graphics area to draw on...
So, lets try a simple QtGui-only app. No QML. Just a QWindow. Darn, no clue how to draw on that. Ok, QWidget it is. And, voila. same problem there...

This is not a QML issue. I'm 90% certain this is a bug in Qt (QWindow, or more likely some Android specific thing code or plugin).

Reported; https://bugreports.qt.io/browse/QTBUG-109268

JoeCFD

@TomZ Good tests! One way to work around this is to get display size from Java code and resize qml window to that size.

JoeCFD

@tubbadu swipe the top or bottom part of your app and you will be able to see top or bottom bar.

TomZ

@JoeCFD said in QML on android does not fill the entire screen:

One way to work around this is to get display size from Java code and resize qml window to that size.

Sounds like something that should be added to Qt.