Animation for the Background Sky

SkyAnimation.java

// Start the animation
mImageView.post(new Runnable() {
    @Override
    public void run() {
        mScaleFactor = (float) mImageView.getHeight() / (float) mImageView.getDrawable().getIntrinsicHeight();
        mMatrix.postScale(mScaleFactor, mScaleFactor);
        mImageView.setImageMatrix(mMatrix);
        animate();
    }
});

// ...
// Create a display rect and matrix for the animation
// Movement should be from right to left.
private void animate() {
    int width = mImageView.getDrawable().getIntrinsicWidth();
    int height = mImageView.getDrawable().getIntrinsicHeight();
    mDisplayRect.set(0, 0, width, height);
    mMatrix.mapRect(mDisplayRect);
    animate(mDisplayRect.left, mDisplayRect.left - (mDisplayRect.right - mImageView.getWidth()));
}

// Use a ValueAnimator to update the view displayed.
private void animate(float from, float to) {
    mCurrentAnimator = ValueAnimator.ofFloat(from, to);
    mCurrentAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            float value = (Float) animation.getAnimatedValue();

            mMatrix.reset();
            mMatrix.postScale(mScaleFactor, mScaleFactor);
            mMatrix.postTranslate(value, 0);

            mImageView.setImageMatrix(mMatrix);
        }
    });
    // Animation takes place over 5s
    mCurrentAnimator.setDuration(5000L);
    mCurrentAnimator.addListener(new AnimatorListenerAdapter() {
        @Override
        public void onAnimationEnd(Animator animation) {
            closeButton.setVisibility(View.VISIBLE);
        }
    });
    mCurrentAnimator.start();
}