ImageUtils.java

/*
 * Copyright (C) 2014 Fastboot Mobile, LLC.
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation; either version 3 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program;
 * if not, see <http://www.gnu.org/licenses>.
 */

package com.fastbootmobile.encore.utils;

import android.annotation.TargetApi;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.os.Build;

import com.fastbootmobile.encore.art.ImageCache;

/**
 * Image processing utility methods
 */
public class ImageUtils {

    /**
     * Get the size in bytes of a bitmap in a BitmapDrawable. Note that from Android 4.4 (KitKat)
     * onward this returns the allocated memory size of the bitmap which can be larger than the
     * actual bitmap data byte count (in the case it was re-used).
     *
     * @param value The bitmap to measure
     * @return size in bytes
     */
    @TargetApi(Build.VERSION_CODES.KITKAT)
    public static int getBitmapSize(BitmapDrawable value) {
        Bitmap bitmap = value.getBitmap();

        // From KitKat onward use getAllocationByteCount() as allocated bytes can potentially be
        // larger than bitmap byte count.
        if (Utils.hasKitKat()) {
            return bitmap.getAllocationByteCount();
        }

        return bitmap.getByteCount();
    }


    /**
     * @param candidate - Bitmap to check
     * @param targetOptions - Options that have the out* value populated
     * @return true if <code>candidate</code> can be used for inBitmap re-use with
     *      <code>targetOptions</code>
     */
    @TargetApi(Build.VERSION_CODES.KITKAT)
    public static boolean canUseForInBitmap(
            Bitmap candidate, BitmapFactory.Options targetOptions) {
        if (!Utils.hasKitKat()) {
            // On earlier versions, the dimensions must match exactly and the inSampleSize must be 1
            return candidate.getWidth() == targetOptions.outWidth
                    && candidate.getHeight() == targetOptions.outHeight
                    && targetOptions.inSampleSize == 1;
        }

        // From Android 4.4 (KitKat) onward we can re-use if the byte size of the new bitmap
        // is smaller than the reusable bitmap candidate allocation byte count.
        if (targetOptions.inSampleSize == 0) {
            targetOptions.inSampleSize = 1;
        }

        int width = targetOptions.outWidth / targetOptions.inSampleSize;
        int height = targetOptions.outHeight / targetOptions.inSampleSize;
        int byteCount = width * height * getBytesPerPixel(candidate.getConfig());
        return byteCount <= candidate.getAllocationByteCount();
    }

    /**
     * Return the byte usage per pixel of a bitmap based on its configuration.
     * @param config The bitmap configuration.
     * @return The byte usage per pixel.
     */
    private static int getBytesPerPixel(Bitmap.Config config) {
        if (config == Bitmap.Config.ARGB_8888) {
            return 4;
        } else if (config == Bitmap.Config.RGB_565) {
            return 2;
        } else if (config == Bitmap.Config.ARGB_4444) {
            return 2;
        } else if (config == Bitmap.Config.ALPHA_8) {
            return 1;
        }
        return 1;
    }

    public static void addInBitmapOptions(BitmapFactory.Options options, ImageCache cache,
                                          int requestedSize, int width, int height) {
        // inBitmap only works with mutable bitmaps so force the decoder to
        // return mutable bitmaps.
        options.inMutable = true;

        // If no inSampleSize is forced, calculate a sampleSize to fit the requested size
        if (options.inSampleSize == 0 && requestedSize > 0) {
            final int originalLargestSide = Math.max(width, height);
            int largestSide = originalLargestSide;
            int factor = 1;
            while (largestSide > requestedSize) {
                factor = factor * 2;
                largestSide = originalLargestSide / factor;
            }

            // We re-divide the factor so that we have an image that is at least large enough.
            // Keeping the factor as is would mean the image can be smaller than the display area.
            if (largestSide == requestedSize) {
                options.inSampleSize = factor;
            } else {
                options.inSampleSize = factor / 2;
            }
        } else if (options.inSampleSize == 0) {
            options.inSampleSize = 1;
        }

        // Try to find a suitable input bitmap to reuse
        if (cache != null) {
            // Try and find a bitmap to use for inBitmap
            Bitmap inBitmap = cache.getBitmapFromReusableSet(options);

            if (inBitmap != null) {
                options.inBitmap = inBitmap;
            }
        }
    }
}