[Interest] Qt 5.6.1 widget app terminates if do not accept Android back key ?

[Federico Buti]

Hi,

Show a toast with "tap again to quit" on the first tap and then quit on the
second tap. That's the common behavior of closing app. It would help in
avoiding accidental closing and confirming to the user that the app is
really going to be quit.

Cheers,
F.

On Oct 7, 2016 9:39 PM, "Eddie Sutton" <eddie.of.the.spam at gmail.com> wrote:


On Oct 7, 2016, at 2:26 PM, Gianluca <gmaxera at gmail.com> wrote:


Il giorno 07 ott 2016, alle ore 20:19, Eddie Sutton <
eddie.of.the.spam at gmail.com> ha scritto:


On Oct 7, 2016, at 2:15 PM, Gianluca <gmaxera at gmail.com> wrote:


Il giorno 07 ott 2016, alle ore 20:09, Eddie Sutton <
eddie.of.the.spam at gmail.com> ha scritto:

Thank you for your reply Jason.

On Oct 7, 2016, at 1:01 PM, Jason H <jhihn at gmx.com> wrote:

It seems like the activity catches it and removes itself from the stack.
Is it crashing? If so paste the exception.


I think maybe you are correct.

I see no exceptions in adb.  Instead it appeared the app was closed
deliberately.

Perhaps the problem is that I do not understand the Android back button.
Does an Android user expect the back button to close an app?


D/TSR     (25898): ../source/source/mainwindow.cpp:812 (virtual void
tcmw::*MainWindow::closeEvent*(QCloseEvent*)):
************************* C L O S E ******************


I/ActivityManager(  563): Process com.ditchwitch.tsr (pid 25898) (adj
9) has died.

I/WindowState(  563): WIN DEATH: Window{42c61a48 u0
com.ditchwitch.tsr/com.ditchwitch.tsr.tsractivity.TsrActivity}

W/WindowManager(  563): Force-removing child win Window{42caa3f8 u0
SurfaceView} from container Window{42c61a48 u0
com.ditchwitch.tsr/com.ditchwitch.tsr.tsractivity.TsrActivity}




I expected Android button to retain my app state, suspend app to
background, then restore suspended state when reactivated.


Default behavior of Android on back button is to terminate the application.
If you don’t want this behavior you have to capture the back button and
handle.
This is not Qt thing … it happens also if you are programming in Java.

http://www.androiduipatterns.com/2011/03/back-button-behavior.html



So most Android users will be irritated if I intercept the back button and
do not let the app close??

I thought the Android back button was supposed to back-track through the
apps the user had opened before the current app.


:-D one thing is what the Android system does by default … another is what
the users except :-D
So, what users except are:
 - if the app is its very first screen, pressing back button will exit from
the app and go to the home screen but when the user will open the app again
is expecting to see exactly the same state as before like the app was in
the background. So you should save the status and restart the app has it
should never been stopped.
 - if the app is into an internal page, pressing back button will just
navigate backward into the history (or app views structure) without exiting
from the app.

But unfortunately this is up to the programmers to do into the Android
world :-(



I think since my UI is a tab control, I will let the app close and any
Bluetooth discovered devices or Bluetooth connections will be closed.

Then re-launching will re-start the app at the default tab and users will
have to scan again for B;bluetooth devices.

Thank you for taking time to explain it to me!

-Ed

>Has anyone seen this?

I cannot find any useful clues in adb.

The app terminates unless I add a keyReleaseEvent to accept the Key_Back.



#if defined(Q_OS_ANDROID)

///

///  Android back button kills TSR ?

///

/// Adding a keyReleaseEvent that accepts the event prevents the crash.

/// I do not understand reason why.

///

/// Ignoring the Android back button will annoy users but is better
than crashing.

///

void MainWindow::keyReleaseEvent(QKeyEvent *event)

{

    if( Qt::Key_Back == event->key())

    {

        qDebug("Android Back button");

        event->setAccepted(true);

    }

}

#endif



Thanks in advance,



-Ed


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