is an example). This can happen in circumstances that are not
manageable by the OSG itself (e.g. 3rd party buggy program) but one
would expect the plugin to be able to recover by returning
ReadResult::ERROR_IN_READING_FILE.
libpng provides two callbacks for warnings and errors - those are
currently unused. By default, they point to function that call exit()
or something similar (the default error callback never returns). This
patch registers the callbacks using libpng's mechanisms, makes the
warning callback emit an osg::notify(osg::WARN) message and the error
callback throw an error. The reading process is enclosed in a
try...catch block. Upon error, the memory is freed and
ReadResult::ERROR_IN_READING_FILE is returned.
"