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 import android.widget.LinearLayout;
  29 import android.widget.ScrollView;
  30
  31 /**
  32  * A PagerAdapter used by PreviewSeekBarPreferenceFragment that for showing multiple preview screen
  33  * regarding a single setting and allowing the user to swipe across them.
  34  */
  35 public class PreviewPagerAdapter extends PagerAdapter {
  36
  37     private FrameLayout[] mPreviewFrames;
  38
  39     /** Duration to use when cross-fading between previews. */
  40     private static final long CROSS_FADE_DURATION_MS = 400;
  41
  42     /** Interpolator to use when cross-fading between previews. */
  43     private static final Interpolator FADE_IN_INTERPOLATOR = new DecelerateInterpolator();
  44
  45     /** Interpolator to use when cross-fading between previews. */
  46     private static final Interpolator FADE_OUT_INTERPOLATOR = new AccelerateInterpolator();
  47
  48     public PreviewPagerAdapter(Context context, int[] previewSampleResIds,
  49                                Configuration[] configurations) {
  50         mPreviewFrames = new FrameLayout[previewSampleResIds.length];
  51
  52         for (int i = 0; i < previewSampleResIds.length; ++i) {
  53             mPreviewFrames[i] = new FrameLayout(context);
  54             mPreviewFrames[i].setLayoutParams(new LinearLayout.LayoutParams(
  55                     LinearLayout.LayoutParams.MATCH_PARENT,
  56                     LinearLayout.LayoutParams.MATCH_PARENT));
  57             mPreviewFrames[i].setContentDescription(
  58                     context.getString(R.string.preview_page_indicator_content_description, i + 1,
  59                             previewSampleResIds.length));
  60
  61             for (Configuration configuration : configurations) {
  62                 // Create a new configuration for the specified value. It won't
  63                 // have any theme set, so manually apply the current theme.
  64                 final Context configContext = context.createConfigurationContext(configuration);
  65                 configContext.setTheme(context.getThemeResId());
  66
  67                 final LayoutInflater configInflater = LayoutInflater.from(configContext);
  68                 final View sampleView = configInflater.inflate(previewSampleResIds[i],
  69                         mPreviewFrames[i], false);
  70                 sampleView.setAlpha(0);
  71                 sampleView.setVisibility(View.INVISIBLE);
  72                 mPreviewFrames[i].addView(sampleView);
  73             }
  74         }
  75     }
  76
  77     @Override
  78     public void destroyItem (ViewGroup container, int position, Object object) {
  79         container.removeView((View) object);
  80     }
  81
  82     @Override
  83     public int getCount() {
  84         return mPreviewFrames.length;
  85     }
  86
  87     @Override
  88     public Object instantiateItem(ViewGroup container, int position) {
  89         container.addView(mPreviewFrames[position]);
  90         return mPreviewFrames[position];
  91     }
  92
  93     @Override
  94     public boolean isViewFromObject(View view, Object object) {
  95         return (view == object);
  96     }
  97
  98     void setPreviewLayer(int newIndex, int currentIndex, int currentItem, boolean animate) {
  99         for (FrameLayout previewFrame : mPreviewFrames) {
 100             if (currentIndex >= 0) {
 101                 final View lastLayer = previewFrame.getChildAt(currentIndex);
 102                 if (animate && previewFrame == mPreviewFrames[currentItem]) {
 103                     lastLayer.animate()
 104                             .alpha(0)
 105                             .setInterpolator(FADE_OUT_INTERPOLATOR)
 106                             .setDuration(CROSS_FADE_DURATION_MS)
 107                             .withEndAction(new Runnable() {
 108                                 @Override
 109                                 public void run() {
 110                                     lastLayer.setVisibility(View.INVISIBLE);
 111                                 }
 112                             });
 113                 } else {
 114                     lastLayer.setAlpha(0);
 115                     lastLayer.setVisibility(View.INVISIBLE);
 116                 }
 117             }
 118
 119             final View nextLayer = previewFrame.getChildAt(newIndex);
 120             if (animate && previewFrame == mPreviewFrames[currentItem]) {
 121                 nextLayer.animate()
 122                         .alpha(1)
 123                         .setInterpolator(FADE_IN_INTERPOLATOR)
 124                         .setDuration(CROSS_FADE_DURATION_MS)
 125                         .withStartAction(new Runnable() {
 126                             @Override
 127                             public void run() {
 128                                 nextLayer.setVisibility(View.VISIBLE);
 129                             }
 130                         });
 131             } else {
 132                 nextLayer.setVisibility(View.VISIBLE);
 133                 nextLayer.setAlpha(1);
 134             }
 135         }
 136     }
 137 }