DnD under Windows needed 3 fixes to work with Gtk.DropTarget.
1. The droptarget_w32format_contentformat_map list never gets
filled so the gdk_win32_drop_read_async throws
"No compatible transfer format found".
This is an easy fix and done the same way in the win32 clipboard code.
2. After a drop no gdk_drop_emit_leave_event gets emitted.
This causes a second drop to trigger a bunch of assertion
'self->drop == drop' failed because the first drop is still active.
This is also an easy fix and done the same way by the macos backend.
3. Handling gdk_drop_status/gdk_drop_get_actions interaction.
In gtk_drop_target_do_drop the code
```gdk_drop_finish (self->drop, gdk_drop_get_actions (self->drop));```
calls the finish operation with the actions of the drop which triggers
```g_return_if_fail (gdk_drag_action_is_unique (action));```
in gdk_drop_finish. The code assumes that GdkDrop::actions gets
narrowed down by calling gdk_drop_status. This is hard to assure
because at the same time gdk_drop_get_actions is used by
gtk_drop_target_accept to figure out if a drag is accepted.
GdkDrop::actions serves a double purpose here as the supported source
actions and the currently agreed on action. Both the x11 and the
wayland backend get this wrong somewhat too. Under wayland/x11 when
a drag coming from a source that supports both MOVE and COPY is
first hovering a drop target that only supports COPY it is afterwards
no longer accepted by other drop targets only accepting MOVE.
Under x11 this is permanent for this drag but with wayland the drag
recovers when hovering other widgets. The win32 backend now sets the
supported source actions before any enter/move/drop and narrows them
down in gdk_win32_drop_status.
The patch only touches the win32 backend and fixes all three issues,
for me restoring DnD under windows.
Closes#4498
It is basically not used by default and is pretty much broken at this point, so
it's about time to drop it.
Let's focus on fixing the OLE2 DnD protocol.
Make _gdk_win32_display_get_monitor_scale_factor() less complex, by:
* Drop the preceding underscore.
* Dropping an unused parameter.
* Using a GdkSurface instead of a HWND, as the HWND that we pass into
this function might have been taken from a GdkSurface, which are now
always created with CS_OWNDC. This means if a GdkSurface was passed
in, we ensure that we only acquire the DC from the HWND once, and do
not attempt to call ReleaseDC() on it.
* Store the HDC that we acquire from the GdkSurface's HWND into the
surface, and use that as the HDC we need for our GdkGLContext.
* Drop the gl_hwnd from GdkWin32Display, as that is really should be
stored in the GdkSurface.
* For functions that were updated, name GdkWin32Display variables as
display_win32 and GdkSurface variables as surface, to unify things.
* Stop calling ReleaseDC() on the HDC that we use for OpenGL, since
they were acquired from HWND's created with CS_OWNDC.
My reading of the code is that gdk_drop_new() is not
consuming the content formats it is given, so the caller
must not pass a new reference.
Needs testing on Windows.
Use better matching format modifiers/specifiers, initialise some things
which in theory wont be written to because of getters using g_return_if_fail(),
a cast, and gsize as input for malloc because gsize!=glong on 64bit Windows.
* There's no GdkDragContext->dest_surface anymore.
Add dest_window field to GdkWin32DragContext,
and use that instead.
* Remove unused function prototypes
* Add more comments
* Rename variables and fields from 'window' to 'surface'
where appropriate
* Fix header indentation a bit
* Try to ensure that uninitialized/unknown handle variables
and fields are set to INVALID_HANDLE_VALUE instead of NULL,
as there may be cases where NULL is a valid handle value.
* Remove clipdrop->dnd_target_state, it's not used anymore
* Remove non-functioning _gdk_dropfiles_store(), store dropfiles
list in GdkWin32Drop instead
* Fix multiple comment typos
* Fix _gdk_win32_get_clipboard_format_name_as_interned_mimetype() to
leave names that look like mime/types alone
* Refactor _gdk_win32_add_w32format_to_pairs() to populate
GdkContentFormatsBuilder directly, instead of making a GList
* Rename context -> drag (still using GdkDragContext type,
but [almost?] all variables and comments say "drag" now)
* Rename GdkDropContext -> GdkDrop
* Rename some parameter names for clarity
* Rewrite local protocol to look more like OLE2 protocol
instead of mirroring the structure of the X11 API.
* Add handle_events field to GdkWin32DragContext,
to shut off event handling (temporary fix until GTK is patched up)
* Remove _gdk_win32_drag_context_find() - the drag object is stored
in GdkDrop instead. Use _gdk_win32_find_drag_for_dest_surface()
to get it initially.
* Remove target_ctx_for_window, droptarget context is stored
in the surface instead.
* Call gdk_drag_context_set_cursor() just like wayland backend does
(slightly broken for now)
* Clean up the action choosing code (filter source actions by using
keyboard state, pass that to GTK, get all actions supported by GTK in
response, match them up with filtered source actions, return the
result, falling back to COPY in case of multiple actions)
* Check drag_win32->protocol instead of the use_ole2_dnd variable where
possible
* Remove protocol checks from functions that are only used by the local
protocol
* Use event state to manufacture the keyboard state for WM_MOUSEMOVE
* Change function names printed by GDK_NOTE to name the actual
functions, not their theoretical generic GDK stack ancestors
* Consistently use drag_win32 and drop_win32 variables instead of a mix
of that and win32_drag/win32_drop
* Return FALSE from button handler to ensure that GTK gets the button
event to break implicit grab
* Emit leave event on failed idroptarget_drop() calls
Add a new W32 backend-specific message filtering mechanism.
Works roughly the same way old event filtering did, but without
events (events are GDK/X11 concept that never really made sense
on W32), so there's no functionality for 'altering' events being
emitted. If an event needs to be emitted in response to a message
do it yourself.
Implemented like this, it should give better performance than
if we were to use GLib signals for this, since W32 sends a LOT
of messages (unlike X11, which doesn't send events as often)
all the time, and invoking the signal machinery on *each* message
would probably be bad.
https://bugzilla.gnome.org/show_bug.cgi?id=773299
Rename GdkWin32Selection to GdkWin32Clipdrop, since GdkSelection
is mostly gone, and the word "selection" does not reflect the
functionality of this object too well.
Clipboard is now handled by a separate thread, most of the code for
it now lives in gdkclipdrop-win32.c, gdkclipboard-win32.c just uses
clipdrop as a backend.
The DnD source part is also put into a thread.
The DnD target part does not spin the main loop, it just
emits a GDK event and returns a default value if it doesn't get a reply
by the time the event is processed.
Both clipboard and DnD use a new GOutputStream subclass to get data
from GTK and put it into a HGLOBAL.
GdkWin32DragContext is split into GdkWin32DragContext and GdkWin32DropContext,
anticipating a similar change that slated to happen to GdkDragContext.
OLE2 DnD protocol is now used by default, set GDK_WIN32_OLE2_DND envvar to 0
to make GDK use the old LOCAL and DROPFILES protocols.
https://bugzilla.gnome.org/show_bug.cgi?id=773299
