src/com/android/settings/PreviewPagerAdapter.java

   1 /*
   2  * Copyright (C) 2016 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 package com.android.settings;
  17
  18 import android.content.Context;
  19 import android.content.res.Configuration;
  20 import android.support.v4.view.PagerAdapter;
  21 import android.view.LayoutInflater;
  22 import android.view.View;
  23 import android.view.ViewGroup;
  24 import android.view.animation.AccelerateInterpolator;
  25 import android.view.animation.DecelerateInterpolator;
  26 import android.view.animation.Interpolator;
  27 import android.widget.FrameLayout;
  28
  29 /**
  30  * A PagerAdapter used by PreviewSeekBarPreferenceFragment that for showing multiple preview screen
  31  * regarding a single setting and allowing the user to swipe across them.
  32  */
  33 public class PreviewPagerAdapter extends PagerAdapter {
  34
  35     private TouchBlockingFrameLayout[] mPreviewFrames;
  36
  37     /** Duration to use when cross-fading between previews. */
  38     private static final long CROSS_FADE_DURATION_MS = 400;
  39
  40     /** Interpolator to use when cross-fading between previews. */
  41     private static final Interpolator FADE_IN_INTERPOLATOR = new DecelerateInterpolator();
  42
  43     /** Interpolator to use when cross-fading between previews. */
  44     private static final Interpolator FADE_OUT_INTERPOLATOR = new AccelerateInterpolator();
  45
  46     public PreviewPagerAdapter(Context context, int[] previewSampleResIds,
  47                                Configuration[] configurations) {
  48         mPreviewFrames = new TouchBlockingFrameLayout[previewSampleResIds.length];
  49
  50         for (int i = 0; i < previewSampleResIds.length; ++i) {
  51             mPreviewFrames[i] = (TouchBlockingFrameLayout) LayoutInflater.from(context)
  52                     .inflate(R.layout.preview_frame_container, null);
  53             mPreviewFrames[i].setContentDescription(
  54                     context.getString(R.string.preview_page_indicator_content_description, i + 1,
  55                             previewSampleResIds.length));
  56
  57             for (Configuration configuration : configurations) {
  58                 // Create a new configuration for the specified value. It won't
  59                 // have any theme set, so manually apply the current theme.
  60                 final Context configContext = context.createConfigurationContext(configuration);
  61                 configContext.setTheme(context.getThemeResId());
  62
  63                 final LayoutInflater configInflater = LayoutInflater.from(configContext);
  64                 final View sampleView = configInflater.inflate(previewSampleResIds[i],
  65                         mPreviewFrames[i], false);
  66                 sampleView.setAlpha(0);
  67                 sampleView.setVisibility(View.INVISIBLE);
  68
  69                 mPreviewFrames[i].addView(sampleView);
  70             }
  71         }
  72     }
  73
  74     @Override
  75     public void destroyItem (ViewGroup container, int position, Object object) {
  76         container.removeView((View) object);
  77     }
  78
  79     @Override
  80     public int getCount() {
  81         return mPreviewFrames.length;
  82     }
  83
  84     @Override
  85     public Object instantiateItem(ViewGroup container, int position) {
  86         container.addView(mPreviewFrames[position]);
  87         return mPreviewFrames[position];
  88     }
  89
  90     @Override
  91     public boolean isViewFromObject(View view, Object object) {
  92         return (view == object);
  93     }
  94
  95     void setPreviewLayer(int newIndex, int currentIndex, int currentItem, boolean animate) {
  96         for (FrameLayout previewFrame : mPreviewFrames) {
  97             if (currentIndex >= 0) {
  98                 final View lastLayer = previewFrame.getChildAt(currentIndex);
  99                 if (animate && previewFrame == mPreviewFrames[currentItem]) {
 100                     lastLayer.animate()
 101                             .alpha(0)
 102                             .setInterpolator(FADE_OUT_INTERPOLATOR)
 103                             .setDuration(CROSS_FADE_DURATION_MS)
 104                             .withEndAction(new Runnable() {
 105                                 @Override
 106                                 public void run() {
 107                                     lastLayer.setVisibility(View.INVISIBLE);
 108                                 }
 109                             });
 110                 } else {
 111                     lastLayer.setAlpha(0);
 112                     lastLayer.setVisibility(View.INVISIBLE);
 113                 }
 114             }
 115
 116             final View nextLayer = previewFrame.getChildAt(newIndex);
 117             if (animate && previewFrame == mPreviewFrames[currentItem]) {
 118                 nextLayer.animate()
 119                         .alpha(1)
 120                         .setInterpolator(FADE_IN_INTERPOLATOR)
 121                         .setDuration(CROSS_FADE_DURATION_MS)
 122                         .withStartAction(new Runnable() {
 123                             @Override
 124                             public void run() {
 125                                 nextLayer.setVisibility(View.VISIBLE);
 126                             }
 127                         });
 128             } else {
 129                 nextLayer.setVisibility(View.VISIBLE);
 130                 nextLayer.setAlpha(1);
 131             }
 132         }
 133     }
 134 }