[Android-development] Warm application start time

Xavier Bigand flamaros.xavier at gmail.com
Wed Jun 15 09:35:50 CEST 2016


You simply have to hide the window on the back button instead of closing
it, it should work.

2016-06-15 9:16 GMT+02:00 ekke <ekke at ekkes-corner.org>:

> Am 15.06.16 um 08:00 schrieb Лагнер, Сергей:
>
> Indeed. I have checked it carefully. I call QApplication quit if my
> StackView has the last Page.
> But what should I do to hide the app once user presses the back button?
>
> just noticed:
> if app becomes inactive because user uses Home or Overview Button,
> re-opening is very fast
> if user uses BACK button app is closed and re-opening took a long time
>
> you can overwrite BACK behavior:
>
>         Keys.onBackPressed: {
>
>             event.accepted = true
>
>             // ...
>
>         }
>
>
> But I don't know how to set the correct state now to avoid closing the app
> from BACK and doing the same as from HOME
>
> ekke
>
>
> 2016-06-15 1:57 GMT+06:00 Xavier Bigand <flamaros.xavier at gmail.com>:
>
>> I don't really understand, because if the process isn't killed Android
>> don't release anything that you have loaded. So normally when the OS put
>> the application back to the active state it should be really fast.
>>
>> With our app we don't have a such issue.
>>
>> Maybe you catch the back button in QML or C++ and you call the
>> QApplication quit method or something else that finally make your
>> application exiting.
>>
>> Try to launch your app with a debugger, you'll see in the console if the
>> process is killed when pressing the back button.
>>
>> 2016-06-14 21:31 GMT+02:00 Лагнер, Сергей < <developer at lagner.ru>
>> developer at lagner.ru>:
>>
>>> Thank you for advice
>>>
>>> We are already doing our best to optimize QML loading time. We use
>>> Loaders from QML side
>>> and lazy loading for models from C++ side. But the application still too
>>> heavy.
>>> It takes 6 sec approximately to launch on Nexus 5.
>>>
>>> Therefore we are looking for other ways to improve our app.
>>>
>>> Now I'm care about warm start.
>>>
>>> Lets consider the following scenario:
>>> - I launch the app. It takes 6 sec.
>>> - Press back and see a home screen
>>> - Launch the app again in a second. And again it takes 6 sec.
>>>
>>> That is mean that all resources were freed and second start was
>>> completely from scratch.
>>> I wonder if I could speed up the second(warm) start from java side.
>>> For example, is it possible so save preloaded native libraries until the
>>> OS has the real lack of memory?
>>>
>>> 2016-06-14 21:56 GMT+06:00 Xavier Bigand < <flamaros.xavier at gmail.com>
>>> flamaros.xavier at gmail.com>:
>>>
>>>> Hi,
>>>>
>>>> If you are using QML you may have to use Loaders to avoid loading of
>>>> GUI parts that are not displayed directly.
>>>> You can also take a look to the QtQuick compiler to improve qml loading.
>>>> There is a profiler on QtCreator for QML which can help you to find
>>>> your binding that are slow, be sure to not having binding loops.
>>>>
>>>> 2016-06-14 16:33 GMT+02:00 Лагнер, Сергей < <developer at lagner.ru>
>>>> developer at lagner.ru>:
>>>>
>>>>> Hi all.
>>>>>
>>>>> I'm trying to optimize start time of my android application. For now
>>>>> I'm interested in warm start time
>>>>> when the user presses back and quickly returns to the app. If we
>>>>> consider java application the
>>>>> warm start is faster, it seems like android caches something or so.
>>>>> But it does not work for Qt applications. My application spends
>>>>> constant time for each start, even if I closed it a second ago.
>>>>>
>>>>> Is there any way to optimize warm start of Qt application?
>>>>> Any hints are highly appreciated.
>>>>>
>>>>> Thanks,
>>>>> Sergey
>>>>>
>>>>> _______________________________________________
>>>>> Android-development mailing list
>>>>> Android-development at qt-project.org
>>>>> http://lists.qt-project.org/mailman/listinfo/android-development
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Xavier
>>>>
>>>
>>>
>>
>>
>> --
>> Xavier
>>
>
>
>
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>
>
> --
>
> ekke
>
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>


-- 
Xavier
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