Rotating/Updating bugs on Android

[timsueberkrueb]

On Android the following problems occur:

• when rotating the screen, the actions of ApplicationWindow are not shown anymore
  • sometimes they show up again after some further rotating
• the ApplicationWindow does not fill the whole screen
  This problems (especially the second one) don't occur on all devices.

Example:

ApplicationWindow {
    initialPage: Page {
        id: main_page
        title: "MyGUS"

        actions: [
            Action {
                iconName: "image/navigate_before"
            },

            Action {
                iconName: "image/navigate_next"
            },

            Action {
                iconName: "navigation/refresh"
            },
        ]
        // ...        
}

The app as it should be ...

Rotated to landscape mode:

Rotated back to portrait mode:

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[MazeChaZer]

I was able to avoid the second problem you describe (the app not filling the whole screen) by removing the width and height properties from the ApplicationWindow component and from the root ApplicationWindow element of my QML app.

[timsueberkrueb]

Hi, @MazeChaZer, I also thought about this, but unfortunately this doesn't work on my testing device:
When I not set any width or height (both in ApplicationWindow.qml and my root element), the app rotates/updates like crazy. It's very strange ...
I made a video of this (because I think it's very hard to believe otherwise ^^):
https://drive.google.com/file/d/0B4EyY4wSGSyjSUlxS1UyNDVvNkU/view?usp=sharing

I'm now using the following workaround:

width: if (Device.type in [Device.phone, Device.phablet, Device.tablet]) {Screen.desktopAvailableWidth} else {Units.dp(800)}
height: if (Device.type in [Device.phone, Device.phablet, Device.tablet]) {Screen.desktopAvailableHeight} else {Units.dp(600)}

This seems to remove the problem for me.

[jneidlinger]

@tim-sueberkrueb Setting the width and height to Screen.desktopAvailableWidth, Screen.desktopAvailableHeight is the correct way to handle this on mobile. This will be the correct dimensions minus status bar, on screen nav buttons, etc.

[MazeChaZer]

@tim-sueberkrueb @jneidlinger Thanks for this information, this helps a lot

[iBelieve]

Do you guys think it would make sense to include @tim-sueberkrueb's solution directly in ApplicationWindow, or should it be left up to the app developer to use that for mobile apps?

[timsueberkrueb]

@ibeliever I'd like it (of course ^^), but there still would be the problem that if the app developer - not knowing about the problem - overrides the height/width in his root component, the problem will still appear.

[MazeChaZer]

@ibeliever I think that would be sensible, although this sounds like an upstream bug to me. I just looked in the Qt Bugtracker but didn't find anything about this issue. Perhaps we should report the problem there? If the Qt guys managed to resolve this issue, we would not need this fix.

[timsueberkrueb]

@MazeChaZer I still don't fully understand what's causing this bug. It only appeared to me when the width/height is set to units.dp(x). I also never experienced this problem using the QtQuick.ApplicationWindow.

[iBelieve]

It does sound like it might be a Qt bug. On Ubuntu Touch, you can set the width and height to whatever you want, and UT just treats the window as maximized - the size you set has no effect.

@tim-sueberkrueb In addition to including your fix, I can add a warning to devs in the documentation.

[jneidlinger]

@ibeliever I think it would be fine to include as default. As long as its documented, a user of the framework can override the default behavior if need be.

[timsueberkrueb]

@jneidlinger @ibeliever Yes, I think this is the best solution, thank you.