Home | History | Annotate | Download | only in deskclock 
      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.deskclock;
     18 
     19 import android.content.Context;
     20 import android.support.v4.view.ViewPager;
     21 import android.util.AttributeSet;
     22 import android.view.MotionEvent;
     23 import android.view.View;
     24 
     25 public class VerticalViewPager extends ViewPager {
     26 
     27     public VerticalViewPager(Context context) {
     28         this(context, null);
     29     }
     30 
     31     public VerticalViewPager(Context context, AttributeSet attrs) {
     32         super(context, attrs);
     33         init();
     34     }
     35 
     36     /**
     37      * @return {@code false} since a vertical view pager can never be scrolled horizontally
     38      */
     39     @Override
     40     public boolean canScrollHorizontally(int direction) {
     41         return false;
     42     }
     43 
     44     /**
     45      * @return {@code true} iff a normal view pager would support horizontal scrolling at this time
     46      */
     47     @Override
     48     public boolean canScrollVertically(int direction) {
     49         return super.canScrollHorizontally(direction);
     50     }
     51 
     52     private void init() {
     53         // Make page transit vertical
     54         setPageTransformer(true, new VerticalPageTransformer());
     55         // Get rid of the overscroll drawing that happens on the left and right (the ripple)
     56         setOverScrollMode(View.OVER_SCROLL_NEVER);
     57     }
     58 
     59     @Override
     60     public boolean onInterceptTouchEvent(MotionEvent ev) {
     61         final boolean toIntercept = super.onInterceptTouchEvent(flipXY(ev));
     62         // Return MotionEvent to normal
     63         flipXY(ev);
     64         return toIntercept;
     65     }
     66 
     67     @Override
     68     public boolean onTouchEvent(MotionEvent ev) {
     69         final boolean toHandle = super.onTouchEvent(flipXY(ev));
     70         // Return MotionEvent to normal
     71         flipXY(ev);
     72         return toHandle;
     73     }
     74 
     75     private MotionEvent flipXY(MotionEvent ev) {
     76         final float width = getWidth();
     77         final float height = getHeight();
     78 
     79         final float x = (ev.getY() / height) * width;
     80         final float y = (ev.getX() / width) * height;
     81 
     82         ev.setLocation(x, y);
     83 
     84         return ev;
     85     }
     86 
     87     private static final class VerticalPageTransformer implements ViewPager.PageTransformer {
     88         @Override
     89         public void transformPage(View view, float position) {
     90             final int pageWidth = view.getWidth();
     91             final int pageHeight = view.getHeight();
     92             if (position < -1) {
     93                 // This page is way off-screen to the left.
     94                 view.setAlpha(0);
     95             } else if (position <= 1) {
     96                 view.setAlpha(1);
     97                 // Counteract the default slide transition
     98                 view.setTranslationX(pageWidth * -position);
     99                 // set Y position to swipe in from top
    100                 float yPosition = position * pageHeight;
    101                 view.setTranslationY(yPosition);
    102             } else {
    103                 // This page is way off-screen to the right.
    104                 view.setAlpha(0);
    105             }
    106         }
    107     }
    108 }
    109