BitmapWorkers.java

/**
 * Created by awave on 2016-07-27.
 */

public class BitmapWorkers {

    public static class BitmapWorkerFile extends AsyncTask<String, Void, Bitmap> {
        private WeakReference<ImageView> imageViewReference = null;
        private Activity mActivity;

        public BitmapWorkerFile() {
        }

        private BitmapWorkerFile(ImageView imageView, Activity a) {
            // Use a WeakReference to ensure the ImageView can be garbage collected
            imageViewReference = new WeakReference<>(imageView);
            mActivity = a;
        }

        @Override
        protected Bitmap doInBackground(String... strings) {
            return decodeSampledBitmapFromPath(strings[0], 300, 300);
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            if (imageViewReference != null && bitmap != null) {
                final ImageView imageView = imageViewReference.get();
                if (imageView != null) {
                    imageView.setImageBitmap(bitmap);
                }
            }
        }

        private static Bitmap decodeSampledBitmapFromPath(String path,
                                                          int reqWidth, int reqHeight) {

            // First decode with inJustDecodeBounds=true to check dimensions
            final BitmapFactory.Options options = new BitmapFactory.Options();
            options.inJustDecodeBounds = true;
            BitmapFactory.decodeFile(path, options);

            // Calculate inSampleSize
            options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

            // Decode bitmap with inSampleSize set
            options.inJustDecodeBounds = false;
            return BitmapFactory.decodeFile(path, options);
        }

        public void loadBitmap(String path, ImageView imageView, Activity a) {
            BitmapWorkerFile task = new BitmapWorkerFile(imageView, a);
            task.execute(path);
        }
    }

    public static class BitmapWorkerRes extends AsyncTask<Integer, Void, Bitmap> {
        private WeakReference<ImageView> imageViewReference = null;
        private Activity mActivity;
        private int data = 0;

        public BitmapWorkerRes() {
        }

        private BitmapWorkerRes(ImageView imageView, Activity a) {
            // Use a WeakReference to ensure the ImageView can be garbage collected
            imageViewReference = new WeakReference<>(imageView);
            mActivity = a;
        }

        // Decode image in background.
        @Override
        protected Bitmap doInBackground(Integer... params) {
            data = params[0];
            return decodeSampledBitmapFromResource(mActivity.getResources(), data, 800, 400);
        }

        // Once complete, see if ImageView is still around and set bitmap.
        @Override
        protected void onPostExecute(Bitmap bitmap) {
            if (imageViewReference != null && bitmap != null) {
                final ImageView imageView = imageViewReference.get();
                if (imageView != null) {
                    imageView.setImageBitmap(bitmap);
                }
            }
        }


        public void loadBitmap(int resId, ImageView imageView, Activity a) {
            BitmapWorkerRes task = new BitmapWorkerRes(imageView, a);
            task.execute(resId);
        }

        private static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
                                                              int reqWidth, int reqHeight) {

            // First decode with inJustDecodeBounds=true to check dimensions
            final BitmapFactory.Options options = new BitmapFactory.Options();
            options.inJustDecodeBounds = true;
            BitmapFactory.decodeResource(res, resId, options);

            // Calculate inSampleSize
            options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

            // Decode bitmap with inSampleSize set
            options.inJustDecodeBounds = false;
            return BitmapFactory.decodeResource(res, resId, options);
        }
    }
}