Collapsing CardView inside RecyclerView when animating

问题

What I'm trying to do

I have a CardView with a supporting text on the bottom that is GONE by default. I want to make this section of the card visible only when the user clicks the "action arrow", as shown on the image below:

I know I can achieve that by simply setting that View visibility to VISIBLE, but I also want to animate the expand and the collapse events.

The problem and what I've tried so far

To do that I've used the android:animateLayoutChanges="true" property on my CardView xml, and it works just fine when it's expanding. But once I click on the arrow again to collapse the supporting text, the card below overlaps the card I've clicked during the animation. How can I avoid this overlapping?

EDIT: I know it may be possible to do something like the solution on this question, but it seems overly complicated since the android:animateLayoutChanges option exists. I wonder if it's possible to solve my issue using that XML property, to keep it simple.

My animation code is as follows:

Java code

protected void expandCard() {
    if (isExpanded) {
        ibt_show_more.animate().rotation(0).start();
        isExpanded = false;
        tv_support.setVisibility(View.GONE);
    }
    else {
        ibt_show_more.animate().rotation(180).start();
        isExpanded = true;
        tv_support.setVisibility(View.VISIBLE);
    }
}

XML code

<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="@dimen/spacing_small"
    card_view:cardCornerRadius="2dp"
    android:id="@+id/os_list_item_cv">

    <RelativeLayout
        android:id="@+id/os_list_item_rl_root"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:animateLayoutChanges="true">

        <!-- Here goes the header, the image, the action buttons and so on -->
        <!-- Omitted on purpose -->
        <!-- ... -->

        <!-- This is the support TextView -->
        <TextView
            android:id="@+id/tv_support"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/os_list_item_rl_actions"
            android:text="@string/bacon_ipsum"
            android:paddingBottom="24dp"
            android:paddingEnd="16dp"
            android:paddingRight="16dp"
            android:paddingLeft="16dp"
            android:paddingStart="16dp"
            android:visibility="gone"/>

    </RelativeLayout>

</android.support.v7.widget.CardView>

GIF for completeness (With wrong collapse behavior)

回答1:

Right before you change the visibility, add this line of code:

TransitionManager.beginDelayedTransition(the rootView containing the cardView, new AutoTransition());

You should get a smooth animation. Also remove "animateLayoutChanges=true" from your xml before this.

As for why this works, calling TransitionManager.beginDelayedTransition() makes the TransitionManger capture current values in the parent ViewGroup and render the animations in the next animation frame. The Transition passed in this case is an AutoTransition, which takes care of all the fading, moving, and resizing in the parent ViewGroup.

See Transitions and TransitionManager

Also take care to use Transitions from the support library where appropriate, or perform the neccessary API level checks.

来源：https://stackoverflow.com/questions/41982987/collapsing-cardview-inside-recyclerview-when-animating

标签

android

android-animation

android-cardview