private Resource<T> decodeFromSourceData(A data) throws IOException {
        final Resource<T> decoded;
        if (diskCacheStrategy.cacheSource()) {
            decoded = cacheAndDecodeSourceData(data);
        } else {
            long startTime = LogTime.getLogTime();
            decoded = loadProvider.getSourceDecoder().decode(data, width, height);
            if (Log.isLoggable(TAG, Log.VERBOSE)) {
                logWithTimeAndKey("Decoded from source", startTime);
            }
        }
        return decoded;
    }
Returns a transformed and transcoded resource decoded from source data, or null if no source data could be
obtained or no resource could be decoded.

<p>
    Depending on the {@link DiskCacheStrategy} used, source data is either decoded
    directly or first written to the disk cache and then decoded from the disk cache.
</p>

@throws Exception
core/src/main/java/com/bumptech/glide/load/engine/DecodeJob.java