Android Open Source - CamTimer Scaled Bitmap Cache

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Back to project page CamTimer.
License

The source code is released under:
GNU General Public License
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Java Source Code

package com.dozingcatsoftware.util;
//from   w  ww  .  j  a  va  2s .  c o  m
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;


import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.net.Uri;
import android.support.v4.util.LruCache;

/** This class implements a two-level cache for Bitmaps. The first level is an in-memory map
 * which uses an LruCache so that the Bitmaps will be freed when necessary. The second
 * level is a location directory on the SD card, where smaller versions of the images
 * will be saved for faster retrieval. The exact location is determined by the ThumbnailLocator
 * implementation passed to the constructor.
 */

public class ScaledBitmapCache {
    
    static int MEMORY_CACHE_SIZE = 2*1024*1024;
  
  public static interface ThumbnailLocator {
    File thumbnailFileForUri(Uri imageUri);
  }
  
  // Simple ThumbnailLocator for putting thumbnails into a single directory using the image URI's filename.
  public static ThumbnailLocator createFixedDirectoryLocator(final String thumbnailDirectory) {
      return new ThumbnailLocator() {
          public File thumbnailFileForUri(Uri imageUri) {
              String filename = imageUri.getLastPathSegment();
              return new File(thumbnailDirectory + File.separator + filename);
          }   
      };
  }

  Context context;
  ThumbnailLocator thumbnailLocator;
  
  LruCache<Uri, Bitmap> scaledBitmapCache = new LruCache<Uri, Bitmap>(MEMORY_CACHE_SIZE) {
      @Override protected int sizeOf(Uri uri, Bitmap bitmap) {
          int size = AndroidUtils.getBitmapByteCount(bitmap);
          return size;
      }
  };
  
  public ScaledBitmapCache(Context context, ThumbnailLocator thumbnailLocator) {
    this.context = context;
    this.thumbnailLocator = thumbnailLocator;
  }
  
  public ScaledBitmapCache(Context context, String imageDirectory) {
    this(context, createFixedDirectoryLocator(imageDirectory));
  }
  
  public Bitmap getInMemoryScaledBitmap(Uri imageUri, int minWidth, int minHeight) {
        Bitmap bitmap = scaledBitmapCache.get(imageUri);
        if (bitmap!=null && bitmap.getWidth()>=minWidth && bitmap.getHeight()>=minHeight) {
            return bitmap;
        }
        return null;
  }
  
  public Bitmap getScaledBitmap(Uri imageUri, int minWidth, int minHeight) {
    Bitmap bitmap = getInMemoryScaledBitmap(imageUri, minWidth, minHeight);
    if (bitmap!=null) return bitmap;
    
    // check thumbnail directory
    File thumbfile = thumbnailLocator.thumbnailFileForUri(imageUri);
    if (thumbfile!=null && thumbfile.isFile()) {
      try {
        bitmap = AndroidUtils.scaledBitmapFromURIWithMinimumSize(context, 
            Uri.fromFile(thumbfile), minWidth, minHeight);
        if (bitmap!=null && bitmap.getWidth()>=minWidth && bitmap.getHeight()>=minHeight) {
          scaledBitmapCache.put(imageUri, bitmap);
          return bitmap;
        }
      }
      catch(Exception ignored) {}
    }
    
    // read full-size image
    try {
      bitmap = AndroidUtils.scaledBitmapFromURIWithMinimumSize(context, imageUri, minWidth, minHeight);
    }
    catch(Exception ex) {
      bitmap = null;
    }
    if (bitmap!=null) {
      // write to in-memory map and save thumbnail image
      scaledBitmapCache.put(imageUri, bitmap);
      try {
        // create thumbnail directory if it doesn't exist
        thumbfile.getParentFile().mkdirs();
        OutputStream thumbnailOutputStream = new FileOutputStream(thumbfile);
        bitmap.compress(CompressFormat.JPEG, 90, thumbnailOutputStream);
        thumbnailOutputStream.close();
        // create .noindex file so thumbnail pictures won't be indexed and show up in the gallery app
        (new File(thumbfile.getParentFile().getPath() + File.separator + ".nomedia")).createNewFile();
      }
      catch(Exception ignored) {}
    }
    return bitmap;
  }
  
  public void removeUri(Uri imageUri) {
    scaledBitmapCache.remove(imageUri);
    thumbnailLocator.thumbnailFileForUri(imageUri).delete();
  }
}
Java Source Code List
