Android: Expand/collapse animation

Question

Let's say I have a vertical linearLayout with :

[v1]
[v2]

By default v1 has visibily = GONE. I would like to show v1 with an expand animation and push down v2 at the same time.

I tried something like this:

Animation a = new Animation()
{
    int initialHeight;

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        final int newHeight = (int)(initialHeight * interpolatedTime);
        v.getLayoutParams().height = newHeight;
        v.requestLayout();
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        super.initialize(width, height, parentWidth, parentHeight);
        initialHeight = height;
    }

    @Override
    public boolean willChangeBounds() {
        return true;
    }
};

But with this solution, I have a blink when the animation starts. I think it's caused by v1 displaying full size before the animation is applied.

With javascript, this is one line of jQuery! Any simple way to do this with android?

Answer 1

Adding to Tom Esterez's excellent answer and Erik B's excellent update to it, I thought I'd post my own take, compacting the expand and contract methods into one. This way, you could for example have an action like this...

button.setOnClickListener(v -> expandCollapse(view));

... which calls the method below and letting it figure out what to do after each onClick()...

public static void expandCollapse(View view) {

    boolean expand = view.getVisibility() == View.GONE;
    Interpolator easeInOutQuart = PathInterpolatorCompat.create(0.77f, 0f, 0.175f, 1f);

    view.measure(
        View.MeasureSpec.makeMeasureSpec(((View) view.getParent()).getWidth(), View.MeasureSpec.EXACTLY),
        View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED)
    );

    int height = view.getMeasuredHeight();
    int duration = (int) (height/view.getContext().getResources().getDisplayMetrics().density);

    Animation animation = new Animation() {
        @Override protected void applyTransformation(float interpolatedTime, Transformation t) {
            if (expand) {
                view.getLayoutParams().height = 1;
                view.setVisibility(View.VISIBLE);
                if (interpolatedTime == 1) {
                    view.getLayoutParams().height = ViewGroup.LayoutParams.WRAP_CONTENT;
                } else {
                    view.getLayoutParams().height = (int) (height * interpolatedTime);
                }
                view.requestLayout();
            } else {
                if (interpolatedTime == 1) {
                    view.setVisibility(View.GONE);
                } else {
                    view.getLayoutParams().height = height - (int) (height * interpolatedTime);
                    view.requestLayout();
                }
            }
        }
        @Override public boolean willChangeBounds() {
            return true;
        }
    };

    animation.setInterpolator(easeInOutQuart);
    animation.setDuration(duration);
    view.startAnimation(animation);

}

Answer 2

Ok, I just found a VERY ugly solution :

public static Animation expand(final View v, Runnable onEnd) {
    try {
        Method m = v.getClass().getDeclaredMethod("onMeasure", int.class, int.class);
        m.setAccessible(true);
        m.invoke(
            v,
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),
            MeasureSpec.makeMeasureSpec(((View)v.getParent()).getMeasuredHeight(), MeasureSpec.AT_MOST)
        );
    } catch (Exception e){
        Log.e("test", "", e);
    }
    final int initialHeight = v.getMeasuredHeight();
    Log.d("test", "initialHeight="+initialHeight);

    v.getLayoutParams().height = 0;
    v.setVisibility(View.VISIBLE);
    Animation a = new Animation()
    {
        @Override
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            final int newHeight = (int)(initialHeight * interpolatedTime);
            v.getLayoutParams().height = newHeight;
            v.requestLayout();
        }

        @Override
        public boolean willChangeBounds() {
            return true;
        }
    };
    a.setDuration(5000);
    v.startAnimation(a);
    return a;
}

Feel free to propose a better solution !

Answer 3

I would like to add something to the very helpful answer above. If you don't know the height you'll end up with since your views .getHeight() returns 0 you can do the following to get the height:

contentView.measure(DUMMY_HIGH_DIMENSION, DUMMY_HIGH_DIMENSION);
int finalHeight = view.getMeasuredHeight();

Where DUMMY_HIGH_DIMENSIONS is the width/height (in pixels) your view is constrained to ... having this a huge number is reasonable when the view is encapsulated with a ScrollView.

Answer 4

@Tom Esterez's answer, but updated to use view.measure() properly per Android getMeasuredHeight returns wrong values !

    // http://easings.net/
    Interpolator easeInOutQuart = PathInterpolatorCompat.create(0.77f, 0f, 0.175f, 1f);

    public static Animation expand(final View view) {
        int matchParentMeasureSpec = View.MeasureSpec.makeMeasureSpec(((View) view.getParent()).getWidth(), View.MeasureSpec.EXACTLY);
        int wrapContentMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
        view.measure(matchParentMeasureSpec, wrapContentMeasureSpec);
        final int targetHeight = view.getMeasuredHeight();

        // Older versions of android (pre API 21) cancel animations for views with a height of 0 so use 1 instead.
        view.getLayoutParams().height = 1;
        view.setVisibility(View.VISIBLE);

        Animation animation = new Animation() {
        @Override
        protected void applyTransformation(float interpolatedTime, Transformation t) {

               view.getLayoutParams().height = interpolatedTime == 1
                    ? ViewGroup.LayoutParams.WRAP_CONTENT
                    : (int) (targetHeight * interpolatedTime);

            view.requestLayout();
        }

            @Override
            public boolean willChangeBounds() {
                return true;
            }
        };

        animation.setInterpolator(easeInOutQuart);
        animation.setDuration(computeDurationFromHeight(view));
        view.startAnimation(animation);

        return animation;
    }

    public static Animation collapse(final View view) {
        final int initialHeight = view.getMeasuredHeight();

        Animation a = new Animation() {
            @Override
            protected void applyTransformation(float interpolatedTime, Transformation t) {
                if (interpolatedTime == 1) {
                    view.setVisibility(View.GONE);
                } else {
                    view.getLayoutParams().height = initialHeight - (int) (initialHeight * interpolatedTime);
                    view.requestLayout();
                }
            }

            @Override
            public boolean willChangeBounds() {
                return true;
            }
        };

        a.setInterpolator(easeInOutQuart);

        int durationMillis = computeDurationFromHeight(view);
        a.setDuration(durationMillis);

        view.startAnimation(a);

        return a;
    }

    private static int computeDurationFromHeight(View view) {
        // 1dp/ms * multiplier
        return (int) (view.getMeasuredHeight() / view.getContext().getResources().getDisplayMetrics().density);
    }

Answer 5

Here is my solution. I think it is simpler. It only expands the view but can easy be extended.

public class WidthExpandAnimation extends Animation
{
    int _targetWidth;
    View _view;

    public WidthExpandAnimation(View view)
    {
        _view = view;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t)
    {
        if (interpolatedTime < 1.f)
        {
            int newWidth = (int) (_targetWidth * interpolatedTime);

            _view.layout(_view.getLeft(), _view.getTop(),
                    _view.getLeft() + newWidth, _view.getBottom());
        }
        else
            _view.requestLayout();
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight)
    {
        super.initialize(width, height, parentWidth, parentHeight);

        _targetWidth = width;
    }

    @Override
    public boolean willChangeBounds() {
        return true;
    }
}

Answer 6

This was my solution, my ImageView grows from 100% to 200% and return to his original size, using two animation files inside res/anim/ folder

anim_grow.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:interpolator="@android:anim/accelerate_interpolator">
 <scale
  android:fromXScale="1.0"
  android:toXScale="2.0"
  android:fromYScale="1.0"
  android:toYScale="2.0"
  android:duration="3000"
  android:pivotX="50%"
  android:pivotY="50%"
  android:startOffset="2000" />
</set>

anim_shrink.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:interpolator="@android:anim/accelerate_interpolator">
 <scale
  android:fromXScale="2.0"
  android:toXScale="1.0"
  android:fromYScale="2.0"
  android:toYScale="1.0"
  android:duration="3000"
  android:pivotX="50%"
  android:pivotY="50%"
  android:startOffset="2000" />
</set>

Send an ImageView to my method setAnimationGrowShrink()

ImageView img1 = (ImageView)findViewById(R.id.image1);
setAnimationGrowShrink(img1);

setAnimationGrowShrink() method:

private void setAnimationGrowShrink(final ImageView imgV){
    final Animation animationEnlarge = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.anim_grow);
    final Animation animationShrink = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.anim_shrink);

    imgV.startAnimation(animationEnlarge);

    animationEnlarge.setAnimationListener(new AnimationListener() {         
        @Override
        public void onAnimationStart(Animation animation) {}

        @Override
        public void onAnimationRepeat(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {
            imgV.startAnimation(animationShrink);
        }
    });

    animationShrink.setAnimationListener(new AnimationListener() {          
        @Override
        public void onAnimationStart(Animation animation) {}

        @Override
        public void onAnimationRepeat(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {
            imgV.startAnimation(animationEnlarge);
        }
    });

}