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Update documentation of the Wayland platform implementation

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ManoloFLTK 2025-03-19 15:34:29 +01:00
parent 4b7cea676b
commit 07bb343de7
1 changed files with 22 additions and 16 deletions
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documentation/src/wayland.dox
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@ -336,17 +336,22 @@ accessible from this object.
For example, when \c interface equals \c "wl_compositor", the value returned by
\c wl_registry_bind() is stored as member \c wl_compositor of the
\c Fl_Wayland_Screen_Driver object.
\c registry_handle_global() also identifies whether the Mutter, Weston, or KWin compositor is connected
and stores this information in static member variable \c Fl_Wayland_Screen_Driver::compositor.
Function \c registry_handle_global() also identifies whether the Mutter, Weston, or KWin compositor
is connected and stores this information in static member variable \c Fl_Wayland_Screen_Driver::compositor.
Other compositors (e.g., \c sway, \c labwc) are not specifically identified by FLTK and
store value \c unspecified in member variable \c compositor.
Wayland calls \c registry_handle_global() with its parameter \c interface equals to
"wl_output" once for each screen connected to the system. Each time, an object of type
<tt>struct wl_output</tt> is created, to which a 4-member listener is associated by function
\c "wl_output" once for each screen connected to the system. Each time, a pointer to a Wayland object
of type <tt>struct wl_output</tt> is obtained by a call to \c wl_registry_bind() and an FLTK
record of type \ref wayland-output "Fl_Wayland_Screen_Driver::output" is created.
This FLTK record is added to the end of the linked list of known screens that starts
at member \c outputs of the \c Fl_Wayland_Screen_Driver object.
A 4-member listener is associated to the <tt>struct wl_output</tt> by function
\c wl_output_add_listener(). The 3rd member of this 4-function listener, \c output_done(),
runs after all initialization steps of the screen have completed and turns to \c true
member \c done of a record of type
\c struct \ref wayland-output "Fl_Wayland_Screen_Driver::output" associated to the
screen. Function \c sync_done() mentioned above therefore also calls \c wl_display_dispatch()
member \c done of the record of type \c Fl_Wayland_Screen_Driver::output.
Function \c sync_done() mentioned above therefore also calls \c wl_display_dispatch()
until the \c done member of all \c Fl_Wayland_Screen_Driver::output records are \c true.
Overall, after return from function \c sync_done(), FLTK has been made aware of all
optional protocols and features of its connected Wayland compositor, and has initialized
@ -356,16 +361,15 @@ Finally, function \c wl_display_get_fd() is called to obtain the file descriptor
and a call to Fl::add_fd() makes FLTK listen to this descriptor in \c FL_READ mode and associates
function \c wayland_socket_callback() from file \c Fl_Wayland_Screen_Driver.cxx with it.
This function calls \c wl_display_dispatch() which reads and interprets data available from the
file descriptor, and calls corresponding listeners.
The \c wl_display_dispatch() call is repeated as long as data are available for reading.
file descriptor, and calls corresponding listeners. Function \c wayland_socket_callback() repeats
the \c wl_display_dispatch() call as long as data are available for reading.
The event loop is run by function \c Fl_Unix_System_Driver::wait() which is used by both
the Wayland and X11 FLTK backends. Among various tasks, this function waits for data arriving
on the file descriptors FLTK is listening. Overall, the event loop of the Wayland backend
is nearly exactly the same as that used by the X11 backend. The Wayland backend differs
only in the callback function handling data read from the Wayland connection socket,
and in overridden functions \c Fl_Wayland_Screen_Driver::poll_or_select_with_delay() and
\c Fl_Wayland_Screen_Driver::poll_or_select().
on the file descriptors FLTK is listening. Overall, the Wayland backend's event loop differs
from that of the X11 backend only in the callback function handling data read from the Wayland
connection socket and in overridden functions \c Fl_Wayland_Screen_Driver::poll_or_select_with_delay()
and \c Fl_Wayland_Screen_Driver::poll_or_select().
\section wayland-surface Wayland windows and surfaces
@ -1410,8 +1414,10 @@ gives access, the Wayland way, to the linked list of displays in the system.
struct Fl_Wayland_Screen_Driver::output { // one record for each display
uint32_t id; // an identifier of the display
int x, y; // logical position of the top-left of display
int width; // nber of horizontal pixels
int height; // nber of vertical pixels
int pixel_width; // in pixels
int pixel_height; // in pixels
int width; // in pixels, account for fractional scaling
int height; // in pixels, account for fractional scaling
float dpi; // at this point, always 96.
struct wl_output *wl_output; // the Wayland object for this display
int wld_scale; // Wayland scale factor