Shared Element Transitions Between Views (not Activities or Fragments)

Question

Let's say I'm using a view-based approach to develop an Android application like for example described in the following article: http://corner.squareup.com/2014/10/advocating-against-android-fragments.html

So now I have two full screen views. One is visible and contains a grid of images. The other is hidden and is a detail view of the to-be-clicked image. Without transitions on clicking an image in the grid the grid view will be hidden and the detail view will be shown. Now what if I want to have something akin to a shared element transition between the small image in the grid view and the larger image in the detail view. Is something like this possible?

Tryptophan

android.transition.Scene ? – Headstock

Answer 1

Yes, transitions allow this.

In your example, you have both the grid and detail views already in your hierarchy. To use transitions, it will work better if the detail view does not start in the View hierarchy. You need to exchange the two views.

There are two (similar) ways to do it. The first is to have the grid view in a scene. Then use TransitionManager.go(detailScene, transition).

The second way is to use TransitionManager.beginDelayedTransition and then swap the detailed layout for the grid layout.

It is important to have the shared views have something in common. Typically it is a View ID or transitionName. This linking will tell the transition system that even though the views are different instances.

The transition that you'll want to use is @android:transition/move. It combines ChangBounds, ChangeTransform, ChangeImageTransform, and ChangeClipBounds. You'll have to target this at the shared element views. It looks like you will need another transition (Fade?) for the entering and /or exiting views.

Something like this:

TransitionSet shared = ...
shared.addTarget("sharedName");
gridElement.setTransitionName("sharedName");
Fade fade = new Fade();
fade.excludeTarget("sharedName", true);
TransitionSet set = new TransitionSet();
set.addTransition(shared)
   .addTransition(fade);
TransitionManager.go(detailScene, set);

Incessant

George, thank you so much for your answer! I have created a quick POC using your approach (github.com/eugenkiss/MaterialEverywhere/commit/…). But if you compare the view-based (shared) transition with the original activity-based transition then you'll see some shortcomings. E.g., the shared element is not drawn on the overlay but instead the previous scene is. Do you see a possibility to improve this approach such that it looks (almost) exactly like the previous activity-based transition? – Tryptophan

I have some good news and some bad news. The good news is that I figured out how to make your app transitions work. The bad news is that it is a little hokey! Both the fade transition and the ChangeTransform add views to the overlay. I don't believe that there is any guarantee for the order of these additions. It just happens to work if you invert adding them to the set (fade first, then shared). The transitionName was also applied to the wrong element (the imageView's container), so ChangeImageTransform couldn't work on it. – Incessant

Thanks, it works (github.com/eugenkiss/MaterialEverywhere/commit/…)! – Tryptophan

I suggest checking this library for transitions : github.com/guerwan/TransitionsBackport – Thud

I like this answers, but this transition is not consistent across all android devices. Possible reason? – Imperfection