isGif

UriUtil.java

public class UriUtil {
    private final Context context;
    private static final byte[] GIF89A_HEADER = {0x47, 0x49, 0x46, 0x38, 0x39, 0x61};
    
    @Inject
    public UriUtil(Context context) {
        this.context = context;
    }
  
    public boolean isGif(Uri input) {
        return hasMagicBytes(input, GIF89A_HEADER);
    }

    private boolean hasMagicBytes(Uri input, byte[] magicBytes) {
        ContentResolver contentResolver = context.getContentResolver();
        InputStream inputStream = null;
        try {
            inputStream = contentResolver.openInputStream(input);
            if (inputStream == null) {
                throw new IOException("cannot open input");
            }
            BufferedSource buffer = Okio.buffer(Okio.source(inputStream));
            byte[] header = new byte[magicBytes.length];
            buffer.read(header);
            return Arrays.equals(header, magicBytes);
        } catch (@SuppressWarnings("OverlyBroadCatchBlock") IOException e) {
            Timber.w(e, "cannot determine file type");
            return false;
        } finally {
            Utils.closeQuietly(inputStream);
        }
    }
}