viewpager pageTransformer

ZoomOutPageTransformer.java

public class ZoomOutPageTransformer implements ViewPager.PageTransformer {


    private static final float MIN_SCALE = 0.85f;
    private static final float MIN_ALPHA = 0.5f;


    @Override
    public void transformPage(View page, float position) {

        int pageWidth = page.getWidth();
        int pageHeight = page.getHeight();

        if (position < -1) {
            //off screen to the left
            page.setAlpha(0);
        } else if (position <= 1) {

            float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
            float vertMargin = pageHeight * (1 - scaleFactor) / 2;
            float horzMargin = pageWidth * (1 - scaleFactor) / 2;

//            if (position < 0) {
//                page.setTranslationX(horzMargin - vertMargin / 2);
//            } else {
//                page.setTranslationX(-horzMargin + vertMargin / 2);
//            }

            page.setScaleX(scaleFactor);
            page.setScaleY(scaleFactor);

            page.setAlpha(MIN_ALPHA+ (scaleFactor- MIN_SCALE) / (1-MIN_SCALE)*(1-MIN_ALPHA));

        }else{
            page.setAlpha(0);
        }

    }
}