package org.wikipedia.page.gallery;

import android.support.v4.view.ViewPager;
import android.view.View;

public class GalleryPagerTransformer implements ViewPager.PageTransformer {
    private static final float MIN_SCALE = 0.9f;

    @Override
    public void transformPage(View view, float position) {
        if (position < -1) { // [-Infinity,-1)
            // This page is way off-screen to the left.
            view.setTranslationX(0);
        } else if (position <= 0) { // [-1,0]
            float scaleFactor = MIN_SCALE + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);
            // fade out
            view.setAlpha(1 + position);
            // keep it in place (undo the default translation)
            view.setTranslationX(-(view.getWidth() * position));
        } else if (position <= 1) { // (0,1]
            // don't do anything to it when it's sliding in.
        } else { // (1,+Infinity]
            // This page is way off-screen to the right.
            view.setTranslationX(0);
        }
    }
}
package org.wikipedia.page.gallery;

import android.support.v4.view.ViewPager;
import android.view.View;

public class GalleryPagerTransformer implements ViewPager.PageTransformer {
    private static final float MIN_SCALE = 0.5f;
    private static final float ROTATION_DEGREES = 30.0f;

    @Override
    public void transformPage(View view, float position) {
        if (position < -1) { // [-Infinity,-1)
            // This page is way off-screen to the left.
        } else if (position <= 0) { // [-1,0]
            float scaleFactor = MIN_SCALE + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);
            // fade out
            view.setAlpha(1 + position);
            // give it a bit of a rotation
            view.setRotationY(-position * ROTATION_DEGREES);
        } else if (position <= 1) { // (0,1]
            float scaleFactor = MIN_SCALE + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);
            // fade out
            view.setAlpha(1 - position);
            // give it a bit of a rotation
            view.setRotationY(-position * ROTATION_DEGREES);
        } else { // (1,+Infinity]
            // This page is way off-screen to the right.
        }
    }
}
--- 
+++ 
@@ -4,31 +4,26 @@
 import android.view.View;
 
 public class GalleryPagerTransformer implements ViewPager.PageTransformer {
-    private static final float MIN_SCALE = 0.5f;
-    private static final float ROTATION_DEGREES = 30.0f;
+    private static final float MIN_SCALE = 0.9f;
 
     @Override
     public void transformPage(View view, float position) {
         if (position < -1) { // [-Infinity,-1)
             // This page is way off-screen to the left.
+            view.setTranslationX(0);
         } else if (position <= 0) { // [-1,0]
             float scaleFactor = MIN_SCALE + (1 - MIN_SCALE) * (1 - Math.abs(position));
             view.setScaleX(scaleFactor);
             view.setScaleY(scaleFactor);
             // fade out
             view.setAlpha(1 + position);
-            // give it a bit of a rotation
-            view.setRotationY(-position * ROTATION_DEGREES);
+            // keep it in place (undo the default translation)
+            view.setTranslationX(-(view.getWidth() * position));
         } else if (position <= 1) { // (0,1]
-            float scaleFactor = MIN_SCALE + (1 - MIN_SCALE) * (1 - Math.abs(position));
-            view.setScaleX(scaleFactor);
-            view.setScaleY(scaleFactor);
-            // fade out
-            view.setAlpha(1 - position);
-            // give it a bit of a rotation
-            view.setRotationY(-position * ROTATION_DEGREES);
+            // don't do anything to it when it's sliding in.
         } else { // (1,+Infinity]
             // This page is way off-screen to the right.
+            view.setTranslationX(0);
         }
     }
 }
[Hackathon] Improve transition between gallery images.

Change-Id: I2edb2195e507d20b31e49637dc19bc751aaee40f
