1 /* 2 * Copyright (C) 2014 Google Inc. 3 * Licensed to The Android Open Source Project. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package com.android.mail.ui; 19 20 import android.support.v4.view.ViewPager; 21 22 import com.android.mail.utils.ViewUtils; 23 24 /** 25 * Helper class for adding RTL support to a ViewPager. Note that this also requires a PagerAdapter 26 * that returns the pages in reversed order in the RTL case. 27 */ 28 public class BidiViewPagerHelper { 29 private ViewPager mViewPager; 30 31 public BidiViewPagerHelper(ViewPager viewPager) { 32 mViewPager = viewPager; 33 } 34 35 public int getFirstPage() { 36 return getBidiIndex(0); 37 } 38 39 public int getLastPage() { 40 return getBidiIndex(mViewPager.getAdapter().getCount() - 1); 41 } 42 43 public int getPreviousPage() { 44 return clampToBounds(getBidiIndex(mViewPager.getCurrentItem() - 1)); 45 } 46 47 public int getNextPage() { 48 return clampToBounds(getBidiIndex(mViewPager.getCurrentItem() + 1)); 49 } 50 51 private int clampToBounds(int position) { 52 return Math.max(0, Math.min(mViewPager.getAdapter().getCount() - 1, position)); 53 } 54 55 private int getBidiIndex(int position) { 56 if (ViewUtils.isViewRtl(mViewPager)) { 57 return mViewPager.getAdapter().getCount() - 1 - position; 58 } else { 59 return position; 60 } 61 } 62 }
