Besides, using std::iostream
on Linux makes impossible to write programs that are binary compatible across different Linux distributions.
Therefore, wxStreams have been added to wxWidgets so that an applications can reliably compile and run on all supported platforms without dependence on a particular release of libg++.
wxStream classes are divided in two main groups:
wxStreamBuffer is a cache manager for wxStreamBase: it manages a stream buffer linked to a stream. One stream can have multiple stream buffers but one stream has always one autoinitialized stream buffer.
wxInputStream is the base class for read-only streams. It implements Read(), SeekI() (I for Input), and all read or IO generic related functions. wxOutputStream does the same thing for write-only streams.
wxFilterInputStream and wxFileterOutputStream are the base class definitions for stream filtering. Stream filtering means a stream which does no syscall but filters data which are passed to it and then pass them to another stream. For example, wxZLibInputStream is an inline stream decompressor.
The "IO" classes implements the specific parts of the stream. This could be nothing in the case of wxMemoryInputStream and wxMemoryOutputStream which base themselves on wxStreamBuffer. This could also be a simple link to the true syscall (for example read(...), write(...)).
... // The constructor initializes the stream buffer and open the file descriptor // associated to the name of the file. wxFileInputStream in_stream("the_file_to_be_read"); // Ok, read some bytes ... nb_datas is expressed in bytes. in_stream.Read(data, nb_datas); if (in_stream.LastError() != wxSTREAM_NOERROR) { // Oh oh, something bad happens. // For a complete list, look into the documentation at wxStreamBase. } // You can also inline all like this. if (in_stream.Read(data, nb_datas).LastError() != wxSTREAM_NOERROR) { // Do something. } // You can also get the last number of bytes REALLY put into the buffer. size_t really_read = in_stream.LastRead(); // Ok, moves to the beginning of the stream. SeekI returns the last position // in the stream counted from the beginning. off_t old_position = in_stream.SeekI(0, wxFromBeginning); // What is my current position ? off_t position = in_stream.TellI(); // wxFileInputStream will close the file descriptor on destruction.
![]() |
[ top ] |