Transform that copies the drawable from a starting ImageView to an ending ImageView

CopyDrawableImageTransform.java

/**
 * Similar to {@link ChangeImageTransform}, but prior to capturing the end values for the transition
 * it will copy the drawable from the starting image to the ending image.
 *
 * This allows the image transform to work when the end ImageView doesn't immediately have content,
 * such as when the image will be loaded via Picasso.
 *
 * @author bherbst
 */
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public class CopyDrawableImageTransform extends ChangeImageTransform {
    private Drawable drawable;

    @Override
    public void captureStartValues(TransitionValues transitionValues) {
        if (transitionValues.view instanceof ImageView) {
            drawable = ((ImageView) transitionValues.view).getDrawable();
        }

        super.captureStartValues(transitionValues);
    }

    @Override
    public void captureEndValues(TransitionValues transitionValues) {
        if (transitionValues.view instanceof ImageView) {
            ImageView imageView = (ImageView) transitionValues.view;
            if (imageView.getDrawable() == null) {
                imageView.setImageDrawable(drawable);
            }
        }

        super.captureEndValues(transitionValues);
    }
}