I see this in every app with theme switching, mine included.
My guess is that when Android performs an activity launch "from nothing",
it runs the launch animation using whatever theme is specified in the
manifest, before any of the app's code is executed.
You can easily test this by setting a title for your activity in the
manifest, and then setting a different one in your onCreate. You should see
the title change (flash) after the animation completes.
It works differently in Chrome, where the launch animation has the "recent
sites" tiles (Chrome does not have a light/dark theme, but we're talking
about being able to control the launch animation).
I believe the reason for this is they handle the back key and use
moveTaskToBackground rather than letting the activity get destroyed.
Again, easy to test: 1) kill Chrome in the app manager, relaunch, watch the
first launch animation after that, it'll be just white without the "recent
sites" tiles 2) press Back in Chrome, use "adb shell dumpsys activity
activities" and you'll see the main Chrome activity in state=STOPPED, not
destroyed.
And actually, it looks like it's not just Chrome.... DialtactsActivity.java
(in Contacts):
@Override
public void onBackPressed() {
if (mInSearchUi) {
// We should let the user go back to usual screens with tabs.
exitSearchUi();
} else if (isTaskRoot()) {
// Instead of stopping, simply push this to the back of the
stack.
// This is only done when running at the top of the stack;
// otherwise, we have been launched by someone else so need to
// allow the user to go back to the caller.
moveTaskToBack(false);
} else {
super.onBackPressed();
}
}
The tradeoff is of course a somewhat higher memory usage, and potentially
emails from users asking "why does your activity keep running, it's really
affecting my battery and has been proven to cause baldness and insomnia".
-- K
On Thursday, January 31, 2013 8:35:32 PM UTC+4, Pent wrote:
>
> Tearing my hair out over this one.
>
> I'm offering the user a choice of several dark or light themes.
> Setting with getApplication().setTheme() and setTheme() in onCreate of
> activity
> (as the first thing in that function).
>
> There's a period while the app loads when the screen goes black. If
> you have a light desktop, it's very disconcerting (flashes). Of course
> I could set a fixed white theme in the manifest, but then the inverse
> problem occurs when user selects a dark theme.
>
> Tried everything I can think of e.g. overrode Application, set in
> Application:onCreate, created a FrontDoor activity that just sets the
> theme then loads the relevant dedicated Light or Dark activity.
>
> It appears Application:setTheme is completely ignored.
>
> The current best solution I have is to set a manifest theme with a
> grey background. Could create dedicated Dark and Light launcher icons,
> but
>
> Any tips ?
>
> Pent
>
> p.s. tried setting a transparent application theme in the manifest,
> then you can get a huge delay while data loads. And if Android is
> short of memory the user keeps seeing the desktop in-between
> activities.
>
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