Defining Z order of views of RelativeLayout in Android

Question

I would like to define the z order of the views of a RelativeLayout in Android.

I know one way of doing this is calling bringToFront.

Is there are better way of doing this? It would be great if I could define the z order in the layout xml.

Answer 1

The easiest way is simply to pay attention to the order in which the Views are added to your XML file. Lower down in the file means higher up in the Z-axis.

Edit: This is documented here and here on the Android developer site. (Thanks @flightplanner)

Answer 2

If you want to do this in code you can do

View.bringToFront();

see docs

Answer 3

Please note, buttons and other elements in API 21 and greater have a high elevation, and therefore ignore the xml order of elements regardless of parent layout. Took me a while to figure that one out.

Answer 4

In Android starting from API level 21, items in the layout file get their Z order both from how they are ordered within the file, as described in correct answer, and from their elevation, a higher elevation value means the item gets a higher Z order.

This can sometimes cause problems, especially with buttons that often appear on top of items that according to the order of the XML should be below them in Z order. To fix this just set the android:elevation of the the items in your layout XML to match the Z order you want to achieve.

I you set an elevation of an element in the layout it will start to cast a shadow. If you don't want this effect you can remove the shadow with code like so:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
   myView.setOutlineProvider(null);
}

I haven't found any way to remove the shadow of a elevated view through the layout xml.

Answer 5

Please note that you can use view.setZ(float) starting from API level 21. Here you can find more info.

Answer 6

I encountered the same issues: In a relative layout parentView, I have 2 children childView1 and childView2. At first, I put childView1 above childView2 and I want childView1 to be on top of childView2. Changing the order of children views did not solve the problem for me. What worked for me is to set android:clipChildren="false" on parentView and in the code I set:

childView1.bringToFront();

parentView.invalidate();

Answer 7

Thought I'd add an answer since the introduction of the

android:translationZ

XML field changed things a tad. The other answers that suggest running

childView1.bringToFront();

parentView.invalidate();

are totally spot on EXCEPT for that this code will NOT bring childView1 in front of any view with a hardcoded android:translationZ in the XML file. I was having problems with this, and once I removed this field from the other views, bringToFront() worked just fine.

Answer 8

childView.bringToFront() didn't work for me, so I set the Z translation of the least recently added item (the one that was overlaying all other children) to a negative value like so:

lastView.setTranslationZ(-10);

see https://developer.android.com/reference/android/view/View.html#setTranslationZ(float) for more

Answer 9

API 21 has view.setElevation(float) build-in

Use ViewCompat.setElevation(view, float); for backward compatibility

More methods ViewCompat.setZ(v, pixels) and ViewCompat.setTranslationZ(v, pixels)

Another way collect buttons or view array and use addView to add to RelativeLayout

Answer 10

Or put the overlapping button or views inside a FrameLayout. Then, the RelativeLayout in the xml file will respect the order of child layouts as they added.

Answer 11

You can use custom RelativeLayout with redefined

protected int getChildDrawingOrder (int childCount, int i)

Be aware - this method takes param i as "which view should I draw i'th". This is how ViewPager works. It sets custom drawing order in conjuction with PageTransformer.

Answer 12

Check if you have any elevation on one of the Views in XML. If so, add elevation to the other item or remove the elevation to solve the issue. From there, it's the order of the views that dictates what comes above the other.

Answer 13

You can use below code sample also for achieving the same

ViewCompat.setElevation(sourceView, ViewCompat.getElevation(mCardView)+1);

This is backward compatible. Here mCardView is a view which should be below sourceView.