Home | History | Annotate | Download | only in documentsui 
      1 /*
      2  * Copyright (C) 2017 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.documentsui;
     17 
     18 import static com.android.documentsui.base.SharedMinimal.VERBOSE;
     19 
     20 import android.content.ContentProviderClient;
     21 import android.content.ContentResolver;
     22 import android.content.Context;
     23 import android.graphics.Bitmap;
     24 import android.graphics.Point;
     25 import android.net.Uri;
     26 import android.os.AsyncTask;
     27 import android.os.CancellationSignal;
     28 import android.os.OperationCanceledException;
     29 import android.provider.DocumentsContract;
     30 import android.util.Log;
     31 import android.view.View;
     32 import android.widget.ImageView;
     33 import com.android.documentsui.ProviderExecutor.Preemptable;
     34 import java.util.function.BiConsumer;
     35 import java.util.function.Consumer;
     36 
     37 /**
     38  *  Loads a Thumbnails asynchronously then animates from the mime icon to the thumbnail
     39  */
     40 public final class ThumbnailLoader extends AsyncTask<Uri, Void, Bitmap> implements Preemptable {
     41 
     42     private static final String TAG = ThumbnailLoader.class.getCanonicalName();
     43 
     44     /**
     45      * Two animations applied to image views. The first is used to switch mime icon and thumbnail.
     46      * The second is used when we need to update thumbnail.
     47      */
     48     public static final BiConsumer<View, View> ANIM_FADE_IN = (mime, thumb) -> {
     49         float alpha = mime.getAlpha();
     50         mime.animate().alpha(0f).start();
     51         thumb.setAlpha(0f);
     52         thumb.animate().alpha(alpha).start();
     53     };
     54     public static final BiConsumer<View, View> ANIM_NO_OP = (mime, thumb) -> {};
     55 
     56     private final ImageView mIconThumb;
     57     private final Point mThumbSize;
     58     private final Uri mUri;
     59     private final long mLastModified;
     60     private final Consumer<Bitmap> mCallback;
     61     private final boolean mAddToCache;
     62     private final CancellationSignal mSignal;
     63 
     64     /**
     65      * @param uri - to a thumbnail.
     66      * @param iconThumb - ImageView to display the thumbnail.
     67      * @param thumbSize - size of the thumbnail.
     68      * @param lastModified - used for updating thumbnail caches.
     69      * @param addToCache - flag that determines if the loader saves the thumbnail to the cache.
     70      */
     71     public ThumbnailLoader(Uri uri, ImageView iconThumb, Point thumbSize, long lastModified,
     72         Consumer<Bitmap> callback, boolean addToCache) {
     73 
     74         mUri = uri;
     75         mIconThumb = iconThumb;
     76         mThumbSize = thumbSize;
     77         mLastModified = lastModified;
     78         mCallback = callback;
     79         mAddToCache = addToCache;
     80         mSignal = new CancellationSignal();
     81         mIconThumb.setTag(this);
     82 
     83         if (VERBOSE) Log.v(TAG, "Starting icon loader task for " + mUri);
     84     }
     85 
     86     @Override
     87     public void preempt() {
     88         if (VERBOSE) Log.v(TAG, "Icon loader task for " + mUri + " was cancelled.");
     89         cancel(false);
     90         mSignal.cancel();
     91     }
     92 
     93     @Override
     94     protected Bitmap doInBackground(Uri... params) {
     95         if (isCancelled()) {
     96             return null;
     97         }
     98 
     99         final Context context = mIconThumb.getContext();
    100         final ContentResolver resolver = context.getContentResolver();
    101 
    102         ContentProviderClient client = null;
    103         Bitmap result = null;
    104         try {
    105             client = DocumentsApplication.acquireUnstableProviderOrThrow(
    106                 resolver, mUri.getAuthority());
    107             result = DocumentsContract.getDocumentThumbnail(client, mUri, mThumbSize, mSignal);
    108             if (result != null && mAddToCache) {
    109                 final ThumbnailCache cache = DocumentsApplication.getThumbnailCache(context);
    110                 cache.putThumbnail(mUri, mThumbSize, result, mLastModified);
    111             }
    112         } catch (Exception e) {
    113             if (!(e instanceof OperationCanceledException)) {
    114                 Log.w(TAG, "Failed to load thumbnail for " + mUri + ": " + e);
    115             }
    116         } finally {
    117             ContentProviderClient.releaseQuietly(client);
    118         }
    119         return result;
    120     }
    121 
    122     @Override
    123     protected void onPostExecute(Bitmap result) {
    124         if (VERBOSE) Log.v(TAG, "Loader task for " + mUri + " completed");
    125 
    126         if (mIconThumb.getTag() == this) {
    127             mIconThumb.setTag(null);
    128             mCallback.accept(result);
    129         }
    130     }
    131 }