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      1 /*
      2  * Copyright (C) 2015 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.calculator2;
     18 
     19 import android.content.Context;
     20 import android.graphics.Color;
     21 import android.support.v4.view.PagerAdapter;
     22 import android.support.v4.view.ViewPager;
     23 import android.util.AttributeSet;
     24 import android.view.MotionEvent;
     25 import android.view.View;
     26 import android.view.ViewGroup;
     27 
     28 public class CalculatorPadViewPager extends ViewPager {
     29 
     30     private final PagerAdapter mStaticPagerAdapter = new PagerAdapter() {
     31         @Override
     32         public int getCount() {
     33             return getChildCount();
     34         }
     35 
     36         @Override
     37         public View instantiateItem(ViewGroup container, int position) {
     38             return getChildAt(position);
     39         }
     40 
     41         @Override
     42         public void destroyItem(ViewGroup container, int position, Object object) {
     43             removeViewAt(position);
     44         }
     45 
     46         @Override
     47         public boolean isViewFromObject(View view, Object object) {
     48             return view == object;
     49         }
     50 
     51         @Override
     52         public float getPageWidth(int position) {
     53             return position == 1 ? 7.0f / 9.0f : 1.0f;
     54         }
     55     };
     56 
     57     private final OnPageChangeListener mOnPageChangeListener = new SimpleOnPageChangeListener() {
     58         @Override
     59         public void onPageSelected(int position) {
     60             for (int i = getChildCount() - 1; i >= 0; --i) {
     61                 final View child = getChildAt(i);
     62                 // Prevent clicks and accessibility focus from going through to descendants of
     63                 // other pages which are covered by the current page.
     64                 child.setClickable(i == position);
     65                 child.setImportantForAccessibility(i == position
     66                         ? IMPORTANT_FOR_ACCESSIBILITY_AUTO
     67                         : IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS);
     68             }
     69         }
     70     };
     71 
     72     private final PageTransformer mPageTransformer = new PageTransformer() {
     73         @Override
     74         public void transformPage(View view, float position) {
     75             if (position < 0.0f) {
     76                 // Pin the left page to the left side.
     77                 view.setTranslationX(getWidth() * -position);
     78                 view.setAlpha(Math.max(1.0f + position, 0.0f));
     79             } else {
     80                 // Use the default slide transition when moving to the next page.
     81                 view.setTranslationX(0.0f);
     82                 view.setAlpha(1.0f);
     83             }
     84         }
     85     };
     86 
     87     public CalculatorPadViewPager(Context context) {
     88         this(context, null /* attrs */);
     89     }
     90 
     91     public CalculatorPadViewPager(Context context, AttributeSet attrs) {
     92         super(context, attrs);
     93 
     94         setAdapter(mStaticPagerAdapter);
     95         setBackgroundColor(Color.BLACK);
     96         setPageMargin(getResources().getDimensionPixelSize(R.dimen.pad_page_margin));
     97         setPageTransformer(false, mPageTransformer);
     98         addOnPageChangeListener(mOnPageChangeListener);
     99     }
    100 
    101     @Override
    102     protected void onFinishInflate() {
    103         super.onFinishInflate();
    104 
    105         // Invalidate the adapter's data set since children may have been added during inflation.
    106         getAdapter().notifyDataSetChanged();
    107 
    108         // Let page change listener know about our initial position.
    109         mOnPageChangeListener.onPageSelected(getCurrentItem());
    110     }
    111 
    112     @Override
    113     public boolean onInterceptTouchEvent(MotionEvent ev) {
    114         boolean shouldIntercept = super.onInterceptTouchEvent(ev);
    115 
    116         // Only allow the current item to receive touch events.
    117         if (!shouldIntercept && ev.getActionMasked() == MotionEvent.ACTION_DOWN) {
    118             final int x = (int) ev.getX() + getScrollX();
    119             final int y = (int) ev.getY() + getScrollY();
    120 
    121             final int childCount = getChildCount();
    122             for (int i = childCount - 1; i >= 0; --i) {
    123                 final int childIndex = getChildDrawingOrder(childCount, i);
    124                 final View child = getChildAt(childIndex);
    125                 if (child.getVisibility() == View.VISIBLE
    126                         && x >= child.getLeft() && x < child.getRight()
    127                         && y >= child.getTop() && y < child.getBottom()) {
    128                     shouldIntercept = (childIndex != getCurrentItem());
    129                     break;
    130                 }
    131             }
    132         }
    133 
    134         return shouldIntercept;
    135     }
    136 }
    137