InputStream read twice when calculating sampled image?

Question

im trying to adapt a method to prevent an outOfMemoryError when reading from an internet bitmap. Do I use it right? Isnt the stream read twice from internet?

BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
URL url = new URL(imageUrl);
InputStream inputStream = url.openConnection().getInputStream();
BitmapFactory.decodeStream(inputStream, null, options);

// Calculate inSampleSize
int coverDimensions = CommonTasks.getDisplayMinSize(getActivity());
options.inSampleSize = calculateInSampleSize(options, coverDimensions, coverDimensions);

 // Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeStream(inputStream, null, options);

private int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        // Raw height and width of image
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            final int halfHeight = height / 2;
            final int halfWidth = width / 2;

            // Calculate the largest inSampleSize value that is a power of 2 and keeps both
            // height and width larger than the requested height and width.
            while ((halfHeight / inSampleSize) > reqHeight
                    && (halfWidth / inSampleSize) > reqWidth) {
                inSampleSize *= 2;
            }
        }

        return inSampleSize;
    }

Answer 1

In the while use || to keep both width and height withing bounds. And no , you cannot reread an InputStream.

No. Theoretically you could use reset() but internet is sequential I/O:

boolen canReset = inputStream.markSupported();
if (canReset) {
    inputStream.mark(Integer.MAX_VALUE);
}
... first read
if (canReset) {
    inputStream.reset();
}
... second read

Instead of a boolean flag, catching an IOException on reset would be easier: it might be thrown anyway when the read limit is exceeded for instance.

Simply reread. The second time it might come from cache.