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Diffstat (limited to 'documentation/src/osissues.dox')
| -rw-r--r-- | documentation/src/osissues.dox | 45 |
1 files changed, 43 insertions, 2 deletions
diff --git a/documentation/src/osissues.dox b/documentation/src/osissues.dox index cc2b4f195..fe25ca2b4 100644 --- a/documentation/src/osissues.dox +++ b/documentation/src/osissues.dox @@ -4,6 +4,7 @@ This appendix describes the operating system specific interfaces in FLTK: \li \ref osissues_accessing +\li \ref osissues_wl_x11_hybrid \li \ref osissues_unix \li \ref osissues_win32 \li \ref osissues_macos @@ -44,8 +45,40 @@ operating system. </TABLE> </CENTER> +\section osissues_wl_x11_hybrid The Wayland/X11 hybrid library + +By default, the FLTK library is, under Linux and Unix, a Wayland/X11 hybrid which +can run FLTK-based apps as Wayland clients or as X11 clients. +The choice between running an app as a Wayland or an X11 client is done as follows, +when the app runs function \c fl_open_display() (that function can be called explicitly by the app +or implicitly by FLTK, for example the first time an Fl_Window is show()'n) : +- if environment variable FLTK_BACKEND is not defined, Wayland is used if a Wayland compositor + is available, otherwise X11 is used; +- if $FLTK_BACKEND equals "wayland", the library makes the app a Wayland client, and stops + with error if no Wayland compositor is available; +- if $FLTK_BACKEND equals "x11", the library makes the app an X11 client even if a Wayland + compositor is available. + +After function \c fl_open_display() has been called, exactly one of the functions \c fl_wl_display() +and \c fl_x11_display() returns a non-NULL value. +When the former function does, the app runs as a Wayland client, +and Wayland-specific functions and symbols described below (\ref osissues_wayland) can be used, whereas +X11-specific functions and symbols cannot. Otherwise, the app runs as an X11 client, and only +X11-specific functions and symbols below (\ref osissues_unix) can be used. + +Because a single app can be expected to run either Wayland or X11, it's necessary to use distinct +names for global variables and functions in the X11- and the Wayland-specific source code. + +Non-default configurations of the FLTK library under Linux/Unix are described in +file README.Wayland.txt. + \section osissues_unix The UNIX (X11) Interface +Cross-platform applications should bracket X11-specific source code between +<tt>\#if defined(FLTK_USE_X11) / \#endif</tt> and should ensure function +\c fl_x11_display() returns non-NULL before calling X11-specific functions and using +X11-specific symbols. + The UNIX interface provides access to the X Window System state information and data structures. @@ -494,6 +527,9 @@ what is done by the gnome and KDE desktops. \section osissues_win32 The Windows Interface +Cross-platform applications should bracket Windows-specific source code between +<tt>\#ifdef _WIN32 / \#endif</tt>. + The Windows interface provides access to the Windows GDI state information and data structures. @@ -712,6 +748,9 @@ version of FLTK: \section osissues_macos The Apple OS X Interface +Cross-platform applications should bracket macOS-specific source code between +<tt>\#if defined(\_\_APPLE\_\_) && !defined(FLTK_USE_X11) / \#endif</tt>. + FLTK supports Apple OS X using the Apple Cocoa library. Older versions of MacOS are no longer supported. @@ -948,8 +987,10 @@ FLTK uses UTF-8-encoded UNIX-style filenames and paths. \section osissues_wayland The Wayland Interface -See file README.Wayland.txt for details about how to organize platform-specific -source code for the Wayland platform. +Cross-platform applications should bracket Wayland-specific source code between +<tt>\#ifdef FLTK_USE_WAYLAND / \#endif</tt> and should ensure function +\c fl_wl_display() returns non-NULL before calling Wayland-specific functions and using +Wayland-specific symbols. extern struct wl_display *fl_wl_display(); \par |