When called from gst_gl_window_win32_close(), internal window
could not exist, and if it does it's going to be destroyed just
after that anyway. Also it causes window_proc() to be called
and crash because it gets a NULL context.
When called from gst_gl_window_win32_set_window_handle() we are
going to set another parent anyway, and it's probably better to
reparent directly instead of passing by a NULL parent which could
cause the internal window to popup briefly.
https://bugzilla.gnome.org/show_bug.cgi?id=749601
gst_gl_context_finalize() is calling gst_gl_window_win32_quit()
which was posting a message. But then window_proc takes window's
context and get a NULL.
Now that we've got a GMainLoop we can do like other backends and
simply call g_main_loop_quit().
This also remove duplicated code to release the parent window and
potential crash there because parent_proc could be NULL if we never
created the internal window. That could happen for example if setting
state to READY then setting a window_handle, and go back to NULL state.
https://bugzilla.gnome.org/show_bug.cgi?id=749601
gst_gl_window_win32_send_message_async() could be called before the
internal window is created so we cannot use PostMessage there.
x11 and wayland backends both create a custom GSource for this,
so there is no reason to not do that for win32.
https://bugzilla.gnome.org/show_bug.cgi?id=749601
Depending on the platform, it was only ever implemented to 1) set a
default surface size, 2) resize based on the video frame or 3) nothing.
Instead, provide a set_preferred_size () that elements/applications
can use to request a certain size which may be ignored for
videooverlay/other cases.
This commit makes the loading of the GModules threadsafe, and
always first tries to load the symbol for the GL library that
is selected for the current context. Only then it falls back
to looking into the current module (NULL), and only as a last
resort the context specific function (e.g. eglGetProcAddress())
is called.
Also add configure parameters to select the names of the library
modules instead of using the defaults, and let the defaults be
independent of the G_MODULE_SUFFIX.
https://bugzilla.gnome.org/show_bug.cgi?id=728753
