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.animation.Animator;
  19 import android.animation.Animator.AnimatorListener;
  20 import android.content.Context;
  21 import android.content.res.Configuration;
  22 import android.support.v4.view.PagerAdapter;
  23 import android.view.LayoutInflater;
  24 import android.view.View;
  25 import android.view.ViewGroup;
  26 import android.view.animation.AccelerateInterpolator;
  27 import android.view.animation.DecelerateInterpolator;
  28 import android.view.animation.Interpolator;
  29 import android.widget.FrameLayout;
  30 import android.widget.LinearLayout;
  31 import android.widget.ScrollView;
  32
  33 /**
  34  * A PagerAdapter used by PreviewSeekBarPreferenceFragment that for showing multiple preview screen
  35  * regarding a single setting and allowing the user to swipe across them.
  36  */
  37 public class PreviewPagerAdapter extends PagerAdapter {
  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     private final FrameLayout[] mPreviewFrames;
  49
  50     private Runnable mAnimationEndAction;
  51
  52     private int mAnimationCounter;
  53
  54     public PreviewPagerAdapter(Context context, int[] previewSampleResIds,
  55                                Configuration[] configurations) {
  56         mPreviewFrames = new FrameLayout[previewSampleResIds.length];
  57
  58         for (int i = 0; i < previewSampleResIds.length; ++i) {
  59             mPreviewFrames[i] = new FrameLayout(context);
  60             mPreviewFrames[i].setLayoutParams(new LinearLayout.LayoutParams(
  61                     LinearLayout.LayoutParams.MATCH_PARENT,
  62                     LinearLayout.LayoutParams.MATCH_PARENT));
  63
  64             for (Configuration configuration : configurations) {
  65                 // Create a new configuration for the specified value. It won't
  66                 // have any theme set, so manually apply the current theme.
  67                 final Context configContext = context.createConfigurationContext(configuration);
  68                 configContext.setTheme(context.getThemeResId());
  69
  70                 final LayoutInflater configInflater = LayoutInflater.from(configContext);
  71                 final View sampleView = configInflater.inflate(previewSampleResIds[i],
  72                         mPreviewFrames[i], false);
  73                 sampleView.setAlpha(0);
  74                 sampleView.setVisibility(View.INVISIBLE);
  75                 mPreviewFrames[i].addView(sampleView);
  76             }
  77         }
  78     }
  79
  80     @Override
  81     public void destroyItem (ViewGroup container, int position, Object object) {
  82         container.removeView((View) object);
  83     }
  84
  85     @Override
  86     public int getCount() {
  87         return mPreviewFrames.length;
  88     }
  89
  90     @Override
  91     public Object instantiateItem(ViewGroup container, int position) {
  92         container.addView(mPreviewFrames[position]);
  93         return mPreviewFrames[position];
  94     }
  95
  96     @Override
  97     public boolean isViewFromObject(View view, Object object) {
  98         return (view == object);
  99     }
 100
 101     boolean isAnimating() {
 102         return mAnimationCounter > 0;
 103     }
 104
 105     void setAnimationEndAction(Runnable action) {
 106         mAnimationEndAction = action;
 107     }
 108
 109     void setPreviewLayer(int newIndex, int currentIndex, int currentItem, boolean animate) {
 110         for (FrameLayout previewFrame : mPreviewFrames) {
 111             if (currentIndex >= 0) {
 112                 final View lastLayer = previewFrame.getChildAt(currentIndex);
 113                 if (animate && previewFrame == mPreviewFrames[currentItem]) {
 114                     lastLayer.animate()
 115                             .alpha(0)
 116                             .setInterpolator(FADE_OUT_INTERPOLATOR)
 117                             .setDuration(CROSS_FADE_DURATION_MS)
 118                             .setListener(new PreviewFrameAnimatorListener())
 119                             .withEndAction(new Runnable() {
 120                                 @Override
 121                                 public void run() {
 122                                     lastLayer.setVisibility(View.INVISIBLE);
 123                                 }
 124                             });
 125                 } else {
 126                     lastLayer.setAlpha(0);
 127                     lastLayer.setVisibility(View.INVISIBLE);
 128                 }
 129             }
 130
 131             final View nextLayer = previewFrame.getChildAt(newIndex);
 132             if (animate && previewFrame == mPreviewFrames[currentItem]) {
 133                 nextLayer.animate()
 134                         .alpha(1)
 135                         .setInterpolator(FADE_IN_INTERPOLATOR)
 136                         .setDuration(CROSS_FADE_DURATION_MS)
 137                         .setListener(new PreviewFrameAnimatorListener())
 138                         .withStartAction(new Runnable() {
 139                             @Override
 140                             public void run() {
 141                                 nextLayer.setVisibility(View.VISIBLE);
 142                             }
 143                         });
 144             } else {
 145                 nextLayer.setVisibility(View.VISIBLE);
 146                 nextLayer.setAlpha(1);
 147             }
 148         }
 149     }
 150
 151     private void runAnimationEndAction() {
 152         if (mAnimationEndAction != null && !isAnimating()) {
 153             mAnimationEndAction.run();
 154             mAnimationEndAction = null;
 155         }
 156     }
 157
 158     private class PreviewFrameAnimatorListener implements AnimatorListener {
 159         @Override
 160         public void onAnimationStart(Animator animation) {
 161             mAnimationCounter++;
 162         }
 163
 164         @Override
 165         public void onAnimationEnd(Animator animation) {
 166             mAnimationCounter--;
 167             runAnimationEndAction();
 168         }
 169
 170         @Override
 171         public void onAnimationCancel(Animator animation) {
 172             // Empty method.
 173         }
 174
 175         @Override
 176         public void onAnimationRepeat(Animator animation) {
 177             // Empty method.
 178         }
 179     }
 180 }