用于垂直滑动的Viewpager变换动画

Question

I am using a vertical swipe in view pager. and am using a tranform animation for it. but when i swipe vertically animation happens horizontally. Can any one show me the error in this code

public class DepthPageTransformer implements ViewPager.PageTransformer {
private static final float MIN_SCALE = 0.75f;

public void transformPage(View view, float position) {
    int pageWidth = view.getWidth();

    if (position < -1) { // [-Infinity,-1)
        // This page is way off-screen to the left.
        view.setAlpha(0);

    } else if (position <= 0) { // [-1,0]
        // Use the default slide transition when moving to the left page
        view.setAlpha(1);
        view.setTranslationX(0);
        view.setScaleX(1);
        view.setScaleY(1);

    } else if (position <= 1) { // (0,1]
        // Fade the page out.
        view.setAlpha(1 - position);

        // Counteract the default slide transition
        view.setTranslationX(pageWidth * -position);

        // Scale the page down (between MIN_SCALE and 1)
        float scaleFactor = MIN_SCALE
                + (1 - MIN_SCALE) * (1 - Math.abs(position));
        view.setScaleX(scaleFactor);
        view.setScaleY(scaleFactor);

    } else { // (1,+Infinity]
        // This page is way off-screen to the right.
        view.setAlpha(0);
    }
}
}

Answer 1

use this code

 public void transformPage(View view, float position) {
            int pageWidth = view.getWidth();

        if (position < -1) { // [-Infinity,-1)
            // This page is way off-screen to the left.
            view.setAlpha(0);

        } else if (position <= 0) { // [-1,0]
            // Use the default slide transition when moving to the left page
            view.setAlpha(1);
            view.setTranslationX(view.getWidth() * -position);

            //set Y position to swipe in from top
            float yPosition = position * view.getHeight();
            view.setTranslationY(yPosition);
            view.setScaleX(1);
            view.setScaleY(1);

        } else if (position <= 1) { // (0,1]
            // Fade the page out.
            view.setAlpha(1 - position);

            // Counteract the default slide transition
            view.setTranslationX(pageWidth * -position);

            // Scale the page down (between MIN_SCALE and 1)
            float scaleFactor = MIN_SCALE
                    + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);

        } else { // (1,+Infinity]
            // This page is way off-screen to the right.
            view.setAlpha(0);
        }
    }

replace [-1,0] code