The Perfect Solution To Convert Immutable Bitmap To A Mutable Bitmap

An acceptable solution to convert immutable bitmap to a mutable bitmap ,using RadomAccessFile to save the source bitmap on disk(no ram memory) and then release it, and after that, loading the file info to another bitmap ,the way is perfectly cut off the ram memory use, it just have one bitmap stored in ram memory per time!!!

>This is the original
/**
* Converts a immutable bitmap to a mutable bitmap. This operation doesn't
* allocates more memory that there is already allocated.
* @param imgIn - Source image. It will be released, and should not be used more
* @return a copy of imgIn, but muttable.
*/
public static Bitmap convertToMutable(Bitmap imgIn) {
try {
// this is the file going to use temporally to save the bytes.
// This file will not be a image, it will store the raw image data.
// File file = new File(Environment.getExternalStorageDirectory() + File.separator + "temp.tmp");
File file = new File(FileUtils.getDiskCacheDir(DataApplication.getContext()) + File.separator + "temp.tmp");

        // Open an RandomAccessFile
        // Make sure you have added uses-permission
        // android:name="android.permission.WRITE_EXTERNAL_STORAGE"
        // into AndroidManifest.xml file
        RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");

        // get the width and height of the source bitmap.
        int width = imgIn.getWidth();
        int height = imgIn.getHeight();
        Config type = imgIn.getConfig();

        // Copy the byte to the file
        // Assume source bitmap loaded using options.inPreferredConfig =
        // Config.ARGB_8888;
        FileChannel channel = randomAccessFile.getChannel();
        MappedByteBuffer map = channel.map(MapMode.READ_WRITE, 0, imgIn.getRowBytes() * height);
        imgIn.copyPixelsToBuffer(map);
        // recycle the source bitmap, this will be no longer used.
        imgIn.recycle();
        System.gc();// try to force the bytes from the imgIn to be released

        // Create a new bitmap to load the bitmap again. Probably the memory
        // will be available.
        imgIn = Bitmap.createBitmap(width, height, type);
        map.position(0);
        // load it back from temporary
        imgIn.copyPixelsFromBuffer(map);
        // close the temporary file and channel , then delete that also
        channel.close();
        randomAccessFile.close();

        // delete the temp file
        file.delete();

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return imgIn;
}

转载于:https://www.cnblogs.com/David-Young/p/6618123.html