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Wayland.dox: more details about window positioning

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ManoloFLTK 2023-03-08 17:52:21 +01:00
parent e409b01ba6
commit dd5dccb30f
1 changed files with 14 additions and 4 deletions
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documentation/src/wayland.dox
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@ -44,8 +44,16 @@ app as parameters of these calls. Each listener is first associated to its corre
Wayland object by a call to a specific Wayland function of the form \c wl_XXX_add_listener().
Wayland differs noticeably from X11 in that the position of a window in the display is
completely hidden to the client app. Besides toplevel and sub-windows, Wayland
allows to create popup windows positioned relatively to a previously mapped other window.
completely hidden to the client app. This prevents function \c Fl_Window::position() from having
any effect on a top-level window. Wayland also prevents a client app from knowing whether
a window is minimized: \c Fl_Window::show() has no effect on an already mapped window.
Subwindows can be positionned as usual relatively to their
parent window. FLTK uses that for the small, yellow windows that display
the new scale factor value when it's changed: these are created as short-lived subwindows
centered above \c Fl::first_window().
Wayland allows to create popup windows positioned relatively to a previously mapped other
window, with the sole restriction that any popup must intersect or at least touch that other
window.
This allows FLTK to create menus and tooltips, but it seriously complicates the algorithm
to pilot menus, because the previous algorithm conceived for other platforms assumes
the position of a window in the display to be known to the client app, which is wrong
@ -280,7 +288,8 @@ above unfold.
\section wayland-graphics-driver Fl_Wayland_Graphics_Driver and Fl_Cairo_Graphics_Driver
Wayland uses an \c Fl_Wayland_Graphics_Driver object for all its on-screen drawing operations.
The Wayland platform of FLTK uses an \c Fl_Wayland_Graphics_Driver object for all its on-screen
drawing operations.
This object is created by function \c Fl_Graphics_Driver::newMainGraphicsDriver() called by
\c Fl_Display_Device::display_device() when the library opens the display.
New \c Fl_Wayland_Graphics_Driver objects are also created for each \c Fl_Image_Surface and
@ -389,7 +398,8 @@ That's done by member function \c Fl_Wayland_Graphics_Driver::create_shm_buffer(
which follows this 3-step procedure to create a "buffer factory" for FLTK and construct
Wayland buffers from it:
- Libdecor function <tt>os_create_anonymous_file(off_t size)</tt> creates an adequate file and mmap's
it. FLTK initially sets this file size to \c pool_size = 10 MB. This size will be increased when and
it. This file lives in RAM because it is created by function \c memfd_create().
FLTK initially sets this file size to \c pool_size = 10 MB. This size will be increased when and
if necessary.
FLTK stores in variable \c pool_memory the address of the beginning of the mmap'ed memory structure.
- Wayland function \c wl_shm_create_pool() has this mmap'ed memory shared with the