shadows/framework/src/main/java/org/robolectric/shadows/ShadowImageDecoder.java
@Implementation
  protected static ImageDecoder nCreate(FileDescriptor fd, Source src) throws IOException {
    return ImageDecoder_nCreateFd(fd, src);
  }
@Implementation
  protected static ImageDecoder nCreate(FileDescriptor fd, Source src) throws IOException {
    return ImageDecoder_nCreateFd(fd, src);
  }
The fd must be seekable.