How to disable the background color when HomeUp is pressed?

Question

Background:

I currently enable the HomeUp button on Activity, thanks to:

getSupportActionBar().setDisplayHomeAsUpEnabled(true);  

According to the Documentation, it's related to setHomeButtonEnabled which:

Enables or disables the "home" button in the corner of the action bar [...] Setting the constant DISPLAY_HOME_AS_UP display option (setDisplayHomeAsUpEnabled method) will automatically enable the home button.

Also, I customize with a selector the state background of items in ActionBar with this style:

<style name="MainTheme" parent="@style/Theme.AppCompat.Light">
    <item name="android:actionBarItemBackground">@drawable/ab_item_background</item>
    <item name="actionBarItemBackground">@drawable/ab_item_background</item>
</style>

Although this works well, I don't want to use a drawable selector for the HomeUp button when UpIndicator is enabled.

Why do I need it:

The ActionBar's background is grey (relative to Theme.AppCompat.Light) and the selector uses a green background when items are pressed. However, the app icon is also green which, when it is pressed, merges with the background pressed state. I need to avoid this by not using a drawable for HomeUp's background.

Question:

How can I achieve this, any idea about a workaround?

Notes:

1. I tried to search a related attribute, which allows to use a custom background for the app icon and UpIndicator, to customize in style.xml but I didn't find it in the Resources.

2. If I use setDisplayHomeAsUpEnabled(true) and setDisplayHomeAsUpEnabled(false), I have the expected behaviour for the Menu Items (backgrounds changed relative to its states) but the HomeUp button, although I have the right behaviour with its background, is no longer enabled.

3. Also, I want to avoid using a CustomView to the ActionBar.

---

Update:

According to Adneal's answer and after tests and researches, here is the results:

 _______________________________________________________________________________
|     |                        |                         |                      |
| API |       R.id.home        |    android.R.id.home    |        method        |
|_____|________________________|_________________________|______________________|
|     |                        |                         |                      |
|  8  |          OK            |           --            |    getParent() x 1   |
| 10  |          OK            |           --            |    getParent() x 1   |
| 11  |          OK            |           --            |    getParent() x 1   |
| 12  |          OK            |           --            |    getParent() x 1   |
| 13  |          OK            |           --            |    getParent() x 1   |
| 14  |          --            |           OK            |    getParent() x 1   |
| 15  |          --            |           OK            |    getParent() x 1   |
| 16  |          --            |           OK            |    getParent() x 1   |
| 17  |          --            |           OK            |    getParent() x 2   |
| 18  |          --            |           OK            |    getParent() x 2   |
| 19  |          --            |           OK            |    getParent() x 2   |
|_____|________________________|_________________________|______________________|

Then, the right condition should be:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
    // retrieve the two parents with "android.R.id.home"
} else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
    // retrieve the first parent with "android.R.id.home"
} else {
    // retrieve the first parent with "R.id.home"
}

Hatti

Answer 1

You can set the background of the home button to null by using View.getParent.

This is the layout that contains the home button, once inflated in ActionBarView, is added to the up container layout which is what actually uses the actionBarItemBackground attribute.

However, AppCompat doesn't utilize an "up container" layout, as well as the normal ActionBar up to API level 18 (Jelly Bean MR2).

So, to change the home button background you'd make one call to View.getParent when using the support library or API levels 11-17's ActionBar, but two when you're changing API level 18+'s.

    View home;
    final int version = Build.VERSION.SDK_INT;
    if (version >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
        // Normal action bar, post-"up container"
        home = (View) findViewById(android.R.id.home).getParent().getParent();
    } else if (version >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        // Normal action bar, pre-"up container"
        home = (View) findViewById(android.R.id.home).getParent();
    } else {
        // Support library action bar
        home = (View) findViewById(R.id.home).getParent();
    }
    home.setBackgroundDrawable(null);

AppCompat could be updated in the future to include to an "up container" layout, so bear in mind you may need to adjust your code later on to accommodate for that.

Laconia

This is exactly what I needed. Thank you very much to share your knowledge and good related links! – Hatti

Adneal, I think there is something wrong in your condition: I get some NullPointerException in API 3.+ with android.R.id.home. That's being said, I changed to ICE_SCREAM_SANDWICH and everything seems to worked well. – Hatti

@Fllo Oh, you're right. I forgot the "up container" wasn't added to the ActionBar until API level 18 (Jelly Bean MR2). I think you meant to type API 13, in which case I can't really say what the ActionBar layout is like because Honeycomb isn't open source, but either way I made an edit. I'm sorry, that's all a little confusing. – Laconia

I updated my answer with several tests I made. The right condition is mentioned in this update part. I think you should update your answer too. Anyway, thanks a lot to have given me the clue. It works definitely well on all API tested. – Hatti

@Fllo Ha, nice table. You should be careful though about API level 17 though. I dove a little deeper and it looks like the "up container" isn't added until 4.2.2_r1, so there are some versions of Jelly Bean that won't work correctly. – Laconia