Animate ImageView between two activities using sha

问题:

I am trying to animate one ImageView to another position between two activities in Android API level 21. Since "MoveImage" in Android L Preview has been removed, I use "ChangeImageTransform" instead, but the sample code in documents doesn't work out (the two images animated separately).

<transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
    <changeImageTransform>
        <targets>
            <target android:targetId="@id/ivA" />
            <target android:targetId="@id/ivB" />
        </targets>
    </changeImageTransform>
</transitionSet>

Is there any working example? Thanks!

回答1:

To make a screen transition animation between two activities that have a shared element, you can read this article and follow the mentioned steps:

1. Enable window content transitions in your theme.
2. Specify a shared elements transition in your style.
3. Define your transition as an XML resource.
4. Assign a common name to the shared elements in both layouts with the android:transitionName attribute.
5. Use the ActivityOptions.makeSceneTransitionAnimation() method.

About the 3rd step, according to the documentation:

In combination with ChangeBounds, ChangeImageTransform allows ImageViews that change size, shape, or ImageView.ScaleType to animate contents smoothly.

The res/transition/your_transition.xml should be like this:

<transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
    <changeBounds>
        <targets>
            <target android:targetId="@id/ivA" />
            <target android:targetId="@id/ivB" />
        </targets>
    </changeBounds>
    <changeImageTransform>
        <targets>
            <target android:targetId="@id/ivA" />
            <target android:targetId="@id/ivB" />
        </targets>
    </changeImageTransform>
</transitionSet>

or simply like this if only ivA and ivB need to be animated:

<transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
    <changeBounds/>
    <changeImageTransform/>
</transitionSet>

回答2:

I have got this working following this guide, a few others, and the referenced material.

A transition set in this style. I put this under res/transition:

<transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
    <changeBounds>
        <targets>
            <target android:targetId="@id/ivA" />
            <target android:targetId="@id/ivB" />
        </targets>
    </changeBounds>
    <changeImageTransform>
        <targets>
            <target android:targetId="@id/ivA" />
            <target android:targetId="@id/ivB" />
        </targets>
    </changeImageTransform>
</transitionSet>

In the source and target ImageViews, you need to add a name tag. The name must be the same.

<ImageView
...
android:transitionName="MYTRANSITIONVIEW"

/>

In styles.xml, add to the application theme:

<item name="android:windowContentTransitions">true</item>
<item name="android:windowActivityTransitions">true</item>
<item name="android:windowSharedElementEnterTransition">@transition/my_transition</item>
<item name="android:windowSharedElementExitTransition">@transition/my_transition</item>

I am running this inside a fragment so I start the new activity like this:

Bundle bundle = null;

if (activity != null) {
    ActivityOptionsCompat options =
                ActivityOptionsCompat.makeSceneTransitionAnimation(activity, Frag2_, "MYTRANSITIONVIEW");
    bundle = options.toBundle();
}
activity.startActivity(i, bundle);

It works on API 21 clients. It did not work on an API 16 client as the XML tags are not valid.

I hope this helps.

Slight update, to get the reverse transition on exit, I had to call

supportFinishAfterTransition();

rather than finish();