android/source/src/java/org/libreoffice/ThumbnailCreator.java

   1 /* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  */
   9 package org.libreoffice;
  10
  11 import android.graphics.Bitmap;
  12 import android.graphics.Color;
  13 import android.graphics.drawable.ColorDrawable;
  14 import android.graphics.drawable.Drawable;
  15 import android.widget.ImageView;
  16
  17 import java.lang.ref.WeakReference;
  18
  19 /**
  20  * Create thumbnails for the parts of the document.
  21  */
  22 public class ThumbnailCreator {
  23     private static final String LOG_TAG = ThumbnailCreator.class.getSimpleName();
  24     private static final int THUMBNAIL_SIZE = 256;
  25
  26     private static boolean needsThumbnailCreation(int partNumber, ImageView imageView) {
  27         ThumbnailCreationTask thumbnailCreationTask = currentThumbnailCreationTask(imageView);
  28
  29         if (thumbnailCreationTask == null) {
  30             return true;
  31         }
  32
  33         if (thumbnailCreationTask.partNumber != partNumber) {
  34             thumbnailCreationTask.cancel();
  35             return true;
  36         } else {
  37             return false;
  38         }
  39     }
  40
  41     private static ThumbnailCreationTask currentThumbnailCreationTask(ImageView imageView) {
  42         if (imageView == null) {
  43             return null;
  44         }
  45         Drawable drawable = imageView.getDrawable();
  46         if (drawable instanceof ThumbnailDrawable) {
  47             return ((ThumbnailDrawable) drawable).thumbnailCreationTask.get();
  48         } else {
  49             return null;
  50         }
  51     }
  52
  53     public void createThumbnail(int partNumber, ImageView imageView) {
  54         if (needsThumbnailCreation(partNumber, imageView)) {
  55             ThumbnailCreationTask task = new ThumbnailCreationTask(imageView, partNumber);
  56             ThumbnailDrawable thumbnailDrawable = new ThumbnailDrawable(task);
  57             imageView.setImageDrawable(thumbnailDrawable);
  58             imageView.setMinimumHeight(THUMBNAIL_SIZE);
  59             LOKitShell.sendThumbnailEvent(task);
  60         }
  61     }
  62
  63     static class ThumbnailDrawable extends ColorDrawable {
  64         public final WeakReference<ThumbnailCreationTask> thumbnailCreationTask;
  65
  66         public ThumbnailDrawable(ThumbnailCreationTask thumbnailCreationTask) {
  67             super(Color.WHITE);
  68             this.thumbnailCreationTask = new WeakReference<ThumbnailCreationTask>(thumbnailCreationTask);
  69         }
  70     }
  71
  72     class ThumbnailCreationTask{
  73         private final WeakReference<ImageView> imageViewReference;
  74         private final int partNumber;
  75         private boolean cancelled = false;
  76
  77         public ThumbnailCreationTask(ImageView imageView, int partNumber) {
  78             imageViewReference = new WeakReference<ImageView>(imageView);
  79             this.partNumber = partNumber;
  80         }
  81
  82         public void cancel() {
  83             cancelled = true;
  84         }
  85
  86         public Bitmap getThumbnail(TileProvider tileProvider) {
  87             int currentPart = tileProvider.getCurrentPartNumber();
  88             tileProvider.changePart(partNumber);
  89             final Bitmap bitmap = tileProvider.thumbnail(THUMBNAIL_SIZE);
  90             tileProvider.changePart(currentPart);
  91             return bitmap;
  92         }
  93
  94         private void changeBitmap(Bitmap bitmap) {
  95             if (cancelled) {
  96                 bitmap = null;
  97             }
  98
  99             if (imageViewReference == null) {
 100                 return;
 101             }
 102             ImageView imageView = imageViewReference.get();
 103             ThumbnailCreationTask thumbnailCreationTask = currentThumbnailCreationTask(imageView);
 104             if (this == thumbnailCreationTask) {
 105                 imageView.setImageBitmap(bitmap);
 106             }
 107         }
 108
 109         public void applyBitmap(final Bitmap bitmap) {
 110             // run on UI thread
 111             LibreOfficeApplication.getMainHandler().post(new Runnable() {
 112                 @Override
 113                 public void run() {
 114                     changeBitmap(bitmap);
 115                 }
 116             });
 117         }
 118     }
 119 }
 120
 121 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */