BitmapUtil.java

/*
Copyright © 2013-2014, Silent Circle, LLC.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
    * Any redistribution, use, or modification is done solely for personal 
      benefit and not for any commercial purpose or for monetary gain
    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name Silent Circle nor the names of its contributors may 
      be used to endorse or promote products derived from this software 
      without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL SILENT CIRCLE, LLC BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/*
 * This  implementation is edited version of original Android sources.
 */

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.silentcircle.contacts.utils;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

/**
 * Provides static functions to decode bitmaps at the optimal size
 */
public class BitmapUtil {
    private BitmapUtil() {}

    /**
     * Returns Width or Height of the picture, depending on which size is smaller. Doesn't actually
     * decode the picture, so it is pretty efficient to run.
     */
    public static int getSmallerExtentFromBytes(byte[] bytes) {
        final BitmapFactory.Options options = new BitmapFactory.Options();

        // don't actually decode the picture, just return its bounds
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options);

        // test what the best sample size is
        return Math.min(options.outWidth, options.outHeight);
    }

    /**
     * Finds the optimal sampleSize for loading the picture
     * @param originalSmallerExtent Width or height of the picture, whichever is smaller
     * @param targetExtent Width or height of the target view, whichever is bigger.
     *
     * If either one of the parameters is 0 or smaller, no sampling is applied
     */
    public static int findOptimalSampleSize(int originalSmallerExtent, int targetExtent) {
        // If we don't know sizes, we can't do sampling.
        if (targetExtent < 1) return 1;
        if (originalSmallerExtent < 1) return 1;

        // Test what the best sample size is. To do that, we find the sample size that gives us
        // the best trade-off between resulting image size and memory requirement. We allow
        // the down-sampled image to be 20% smaller than the target size. That way we can get around
        // unfortunate cases where e.g. a 720 picture is requested for 362 and not down-sampled at
        // all. Why 20%? Why not. Prove me wrong.
        int extent = originalSmallerExtent;
        int sampleSize = 1;
        while ((extent >> 1) >= targetExtent * 0.8f) {
            sampleSize <<= 1;
            extent >>= 1;
        }

        return sampleSize;
    }

    /**
     * Decodes the bitmap with the given sample size
     */
    public static Bitmap decodeBitmapFromBytes(byte[] bytes, int sampleSize) {
        final BitmapFactory.Options options;
        if (sampleSize <= 1) {
            options = null;
        } else {
            options = new BitmapFactory.Options();
            options.inSampleSize = sampleSize;
        }
        return BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options);
    }
}