private void zoomImageFromThumb(final View thumbView, int imageResId) {
        // If there's an animation in progress, cancel it immediately and proceed with this one.
        if (mCurrentAnimator != null) {
            mCurrentAnimator.cancel();
        }

        // Load the high-resolution "zoomed-in" image.
        final ImageView expandedImageView = (ImageView) findViewById(R.id.expanded_image);
        expandedImageView.setImageResource(imageResId);

        // Calculate the starting and ending bounds for the zoomed-in image. This step
        // involves lots of math. Yay, math.
        final Rect startBounds = new Rect();
        final Rect finalBounds = new Rect();
        final Point globalOffset = new Point();

        // The start bounds are the global visible rectangle of the thumbnail, and the
        // final bounds are the global visible rectangle of the container view. Also
        // set the container view's offset as the origin for the bounds, since that's
        // the origin for the positioning animation properties (X, Y).
        thumbView.getGlobalVisibleRect(startBounds);
        findViewById(R.id.container).getGlobalVisibleRect(finalBounds, globalOffset);
        startBounds.offset(-globalOffset.x, -globalOffset.y);
        finalBounds.offset(-globalOffset.x, -globalOffset.y);

        // Adjust the start bounds to be the same aspect ratio as the final bounds using the
        // "center crop" technique. This prevents undesirable stretching during the animation.
        // Also calculate the start scaling factor (the end scaling factor is always 1.0).
        float startScale;
        if ((float) finalBounds.width() / finalBounds.height()
                > (float) startBounds.width() / startBounds.height()) {
            // Extend start bounds horizontally
            startScale = (float) startBounds.height() / finalBounds.height();
            float startWidth = startScale * finalBounds.width();
            float deltaWidth = (startWidth - startBounds.width()) / 2;
            startBounds.left -= deltaWidth;
            startBounds.right += deltaWidth;
        } else {
            // Extend start bounds vertically
            startScale = (float) startBounds.width() / finalBounds.width();
            float startHeight = startScale * finalBounds.height();
            float deltaHeight = (startHeight - startBounds.height()) / 2;
            startBounds.top -= deltaHeight;
            startBounds.bottom += deltaHeight;
        }

        // Hide the thumbnail and show the zoomed-in view. When the animation begins,
        // it will position the zoomed-in view in the place of the thumbnail.
        thumbView.setAlpha(0f);
        expandedImageView.setVisibility(View.VISIBLE);

        // Set the pivot point for SCALE_X and SCALE_Y transformations to the top-left corner of
        // the zoomed-in view (the default is the center of the view).
        expandedImageView.setPivotX(0f);
        expandedImageView.setPivotY(0f);

        // Construct and run the parallel animation of the four translation and scale properties
        // (X, Y, SCALE_X, and SCALE_Y).
        AnimatorSet set = new AnimatorSet();
        set
                .play(ObjectAnimator.ofFloat(expandedImageView, View.X, startBounds.left,
                        finalBounds.left))
                .with(ObjectAnimator.ofFloat(expandedImageView, View.Y, startBounds.top,
                        finalBounds.top))
                .with(ObjectAnimator.ofFloat(expandedImageView, View.SCALE_X, startScale, 1f))
                .with(ObjectAnimator.ofFloat(expandedImageView, View.SCALE_Y, startScale, 1f));
        set.setDuration(mShortAnimationDuration);
        set.setInterpolator(new DecelerateInterpolator());
        set.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                mCurrentAnimator = null;
            }

            @Override
            public void onAnimationCancel(Animator animation) {
                mCurrentAnimator = null;
            }
        });
        set.start();
        mCurrentAnimator = set;

        // Upon clicking the zoomed-in image, it should zoom back down to the original bounds
        // and show the thumbnail instead of the expanded image.
        final float startScaleFinal = startScale;
        expandedImageView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (mCurrentAnimator != null) {
                    mCurrentAnimator.cancel();
                }

                // Animate the four positioning/sizing properties in parallel, back to their
                // original values.
                AnimatorSet set = new AnimatorSet();
                set
                        .play(ObjectAnimator.ofFloat(expandedImageView, View.X, startBounds.left))
                        .with(ObjectAnimator.ofFloat(expandedImageView, View.Y, startBounds.top))
                        .with(ObjectAnimator
                                .ofFloat(expandedImageView, View.SCALE_X, startScaleFinal))
                        .with(ObjectAnimator
                                .ofFloat(expandedImageView, View.SCALE_Y, startScaleFinal));
                set.setDuration(mShortAnimationDuration);
                set.setInterpolator(new DecelerateInterpolator());
                set.addListener(new AnimatorListenerAdapter() {
                    @Override
                    public void onAnimationEnd(Animator animation) {
                        thumbView.setAlpha(1f);
                        expandedImageView.setVisibility(View.GONE);
                        mCurrentAnimator = null;
                    }

                    @Override
                    public void onAnimationCancel(Animator animation) {
                        thumbView.setAlpha(1f);
                        expandedImageView.setVisibility(View.GONE);
                        mCurrentAnimator = null;
                    }
                });
                set.start();
                mCurrentAnimator = set;
            }
        });
    }
"Zooms" in a thumbnail view by assigning the high resolution image to a hidden "zoomed-in"
image view and animating its bounds to fit the entire activity content area. More
specifically:
<p>
<ol>
<li>Assign the high-res image to the hidden "zoomed-in" (expanded) image view.</li>
<li>Calculate the starting and ending bounds for the expanded view.</li>
<li>Animate each of four positioning/sizing properties (X, Y, SCALE_X, SCALE_Y)
simultaneously, from the starting bounds to the ending bounds.</li>
<li>Zoom back out by running the reverse animation on click.</li>
</ol>

@param thumbView  The thumbnail view to zoom in.
@param imageResId The high-resolution version of the image represented by the thumbnail.
app/src/main/java/home/smart/fly/animations/ui/activity/demos/ZoomActivity.java