In non-composited environments, we were ending up with all-black
drag icons, because nothing was drawing the background of our new
toplevel. Fix this by drawing background when we are not composited.
We don't do this when composited, since we want to allow transparent
icons.
The documentation clearly says that the widget is not destroyed,
but we were in fact failing to keep it alive, since it was still
a child or the icon_window when we destroy that. Fix this by
reparenting the icon_widget out before. Also, deal with the
possibility that the application might destroy the widget
halfway through, for whatever reason.
We should conform to a minimal set of reasons for the gtk side to emit
a better GtkDragResult than GTK_DRAG_RESULT_ERROR. This fixes the notebook
tab DnD feature, where we rely on GTK_DRAG_RESULT_NO_TARGET.
In the wayland side, unfortunately we can't honor either NO_TARGET nor
USER_CANCELLED, we don't know of the latter, so we could return false
positives on the former.
https://bugzilla.gnome.org/show_bug.cgi?id=761954
Grabbing must stay a bit longer until all other backends than x11/wayland
catch up with GDK DnD, so ignore deprecation flags are used on those. The
uses of GdkDeviceManager can be entirely avoided though.
When this is in use, there's essentially a bunch of dead code here.
When all backends are ported, we'll be able to remove grab/cursor
management plus a bunch of source-side event handlers.
I hadn't noticed the :drop() pseudo state in the CSS4 Selectors
spec when I added this a while ago. This commit renames
GTK_STATE_FLAG_DND to GTK_STATE_FLAG_DROP_ACTIVE and adds
:drop(active) as equivalent to the :dnd pseudo state.
Remove some now unused includes and dead code, and rename
gtk_drag_set_icon_window to gtk_drag_set_icon_widget_internal,
since it is no longer restricted to toplevel windows.
Under Wayland, the compositor does it, so there is no need
for us to move the window ourselves. For X11, we are now
doing the animation from the X11 backend. Trigger that by
calling gdk_drag_drop_done().
What changes here is that we have to keep the icon_window
alive for as long as the drag context exists. Use a weak
reference to do so.
When we start a drag cancel animation, we can just keep the existing
window. The reset was only necessary to convert from cursor icon to
window and we removed the cursor handling.
The Wayland dnd surface must remain in place until the drag
is over. Setting it directly as the hardcoded window of the
widget we construct carries the danger that it might get
destroyed prematurely, e.g. when the application calls
gtk_drag_set_icon_name more than once and we recreate the
widget.
Instead, create a dedicated toplevel, and reparent the widget
into it. To keep the code simple, we use the same approach
under X11 as well, and make it the responsibility of the
GDK dnd code to keep the window position updated. We already
pass the current pointer position to gdk_drag_motion, which
makes this very easy.
As a side-effect of these changes, it is now possible to use
non-toplevel widgets as drag icons.
https://bugzilla.gnome.org/show_bug.cgi?id=748763
The size of icons is a property that is relevant to who is rendering the
icon, not to the icon itself.
Example: Starting a DND operation from an entry icon should cause the
icon to resize (from the entr icon's size to the DND icon size).
Make gtk_icon_helper_ensure_surface() a private function that just
ensures the surface was loaded.
Add gtk_icon_helper_load_surface() that is called by the above function
and the dnd code to actually load the surface.
This is wrong by all accounts there, as we can do no tricks there to show
a "drag failed" animation, which is performed by the compositor itself
on wayland.
The current widget lookup code bails out on insensitive widgets, there's
however legit cases where we want DnD handled by a parent of the insensitive
widget, so just keep going upwards in that case.
We also use now the widget state flags, because get_sensitive() doesn't
propagate across hierarchies, so we could conceivably find a drop site
inside an insensitive widget.
https://bugzilla.gnome.org/show_bug.cgi?id=751793
