// <!-*-C++-*- file: wstream.h --->
// <!-------------------------------------------------------------------------->
// <! Copyright (C) 1995 Dietmar Kuehl >
// <!>
// <! This file is free software; you can redistribute it and/or modify >
// <! it under the terms of the GNU General Public License as published by >
// <! the Free Software Foundation; either version 2 of the License, or >
// <! (at your option) any later version. >
// <!>
// <! This program is distributed in the hope that it will be useful, >
// <! but WITHOUT ANY WARRANTY; without even the implied warranty of >
// <! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >
// <! GNU General Public License for more details. >
//----------------------------------------------------------------------------
// <HTML>
// <HEAD>
// <TITLE> wstream.h - Header File for a Specialized IOstream </TITLE>
// <H1>Header File for a Specialized IOstream</H1>
// <H2>Writing into a Motif Text Widget</H2>
// <HR>
// </HEAD>
This page includes a header file used to declare a specialized
ostream and streambuf: The widgetbuf derived from streambuf is used
to write text to a Motif text widget. A Motif text widget is used
as external representation because I needed such an ostream myself
and because I have seen several request how to solve a similar
problem in conjunction with MS Windows. I couldn't write an MS Windows
example because I haven't any experience with that (thus there is also
no point in asking me for MS Windows related code doing a similar thing).
However, it should not be a problem to change the code to write to another
external representation.
For further information about iostreams see a documentation of this stuff.
Most of the knowledge I have about iostreams comes from
C++ IOStreams Handbook
Steve Teale
Addison-Wesley
ISBN 0-201-59641-5
#ifndef _WSTREAM_H_ #define _WSTREAM_H_ // </PRE>----------------------------------------------------------------------------Next the necessary header files are included: iostream.h is needed for the declaration of ostream and streambuf. In the headerfile Intrinsic.h declaration of Widget is found.#include <iostream.h> #include <X11/Intrinsic.h> // </PRE>----------------------------------------------------------------------------The important part is the declaration of a class derived from streambuf. This class is used to put characters into and get characters from some "extrenal representation", e.g. a file. In this case characters are put into a widget. Thus the derived class is called 'widgetbuf'. Currently only the putting of characters is implemented...
The important functions for this class are 'overflow()' which is called if the internal buffer of the widgetbuf is full and some character should be placed in there and the 'sync()' which is called when the external representation is to be brought into synchronization with the buffers representation (e.g. if an 'endl' or an '\n' is put into a stream). The other functions are used for construction/destruction of the object and for uses internal to the implementation (see wstream.cc):class widgetbuf: public streambuf { private: Widget text; void put_buffer(void); void put_char(int); protected: int overflow(int); int sync(); public: widgetbuf(Widget, int = 0); ~widgetbuf(); }; // </PRE>---------------------------------------------------------------------------- To make the use of the widgetbuf more convinient a class derived from ostream is supported which only initializes an ostream with a widgetbuf as streambuf. It is also possible to directly allocate a widgetbuf and initialize an ostream with it. Thus this class is not really necessary:class owstream: public ostream { public: owstream(Widget, int = 0); };---------------------------------------------------------------------------- Finally there has to be a proper termination of the header file:#endif /* _WSTREAM_H_ */
Please send comments, suggestions, problem reports, bug fixes etc. to
Dietmar Kühl: Dietmar.Kuehl@claas-solutions.de
Please send comments, suggestions, problem reports, bug fixes etc. to
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