android - How to start shared element transition using Fragments?

Question

I am trying to implement transitions between fragments which have "shared elements" as described in the new material design specs. The only method I can find is the ActivityOptionsCompat.makeSceneTransitionAnimation, which I believe works on Activity only. I've been searching for this same functionality but with/for fragments.

Answer 1

I had the same problem but had it working by adding a new fragment from another fragment. The following link is very helpful in getting started on this: https://developer.android.com/training/material/animations.html#Transitions

Following is my code that works. I'm animating an ImageView from one fragment to the other. Make sure the View you want to animate has the same android:transitionName in both fragments. The other content doesn't really matter.

As a test, you could copy this to both your layout xml files. Make sure the image exists.

<ImageView
android:transitionName="MyTransition"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
android:src="@drawable/test_image" />

Then I have 1 file in my res/transition folder, named change_image_transform.xml.

<?xml version="1.0" encoding="utf-8"?>
<transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
    <changeImageTransform />
</transitionSet>

Now you can get started. Lets say you have Fragment A containing the image and want to add Fragment B.

Run this in Fragment A:

@Override
public void onClick(View v) {
    switch(v.getId()) {
        case R.id.product_detail_image_click_area:
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                setSharedElementReturnTransition(TransitionInflater.from(getActivity()).inflateTransition(R.transition.change_image_transform));
                setExitTransition(TransitionInflater.from(getActivity()).inflateTransition(android.R.transition.explode));

                // Create new fragment to add (Fragment B)
                Fragment fragment = new ImageFragment();
                fragment.setSharedElementEnterTransition(TransitionInflater.from(getActivity()).inflateTransition(R.transition.change_image_transform));
                fragment.setEnterTransition(TransitionInflater.from(getActivity()).inflateTransition(android.R.transition.explode));

                // Our shared element (in Fragment A)
                mProductImage   = (ImageView) mLayout.findViewById(R.id.product_detail_image);

                // Add Fragment B
                FragmentTransaction ft = getFragmentManager().beginTransaction()
                        .replace(R.id.container, fragment)
                        .addToBackStack("transaction")
                        .addSharedElement(mProductImage, "MyTransition");
                ft.commit();
            }
            else {
                // Code to run on older devices
            }
            break;
    }
}