data-device: Implement DnD actions

The policy in weston in order to determine the chosen DnD action is
deliberately simple, and is probably the minimals that any compositor
should be doing here.

Besides honoring the set_actions requests on both wl_data_source and
wl_data_offer, weston now will emit the newly added "action" events
notifying both source and dest of the chosen action.

The "dnd" client has been updated too (although minimally), so it
notifies the compositor of a "move" action on both sides.

Changes since v8:
  - Add back wl_data_offer.source_actions emission, gone during last
    code shuffling. Fix nits found in review.

Changes since v7:
  - Fixes spotted during review. Add client-side version checks.
    Implement .action emission as specified in protocol patch v11.

Changes since v6:
  - Emit errors as defined in DnD actions patch v10.

Changes since v5:
  - Use enum types and values for not-a-bitfield stored values.
    handle errors when finding unexpected dnd_actions values.

Changes since v4:
  - Added compositor-side version checks. Spaces vs tabs fixes.
    Fixed resource versioning. Initialized new weston_data_source/offer
    fields.

Changes since v3:
  - Put data_source.action to use in the dnd client, now updates
    the dnd surface like data_source.target events do.

Changes since v2:
  - Split from DnD progress notification changes.

Changes since v1:
  - Updated to v2 of DnD actions protocol changes, implement
    wl_data_offer.source_actions.
  - Fixed coding style issues.

Signed-off-by: Carlos Garnacho <carlosg@gnome.org>
Reviewed-by: Michael Catanzaro <mcatanzaro@igalia.com>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>

clients/dnd.c

@@ -72,6 +72,7 @@ struct dnd_drag {
 	struct item *item;
 	int x_offset, y_offset;
 	int width, height;
+	uint32_t dnd_action;
 	const char *mime_type;
 
 	struct wl_surface *drag_surface;
@@ -266,16 +267,13 @@ dnd_get_item(struct dnd *dnd, int32_t x, int32_t y)
 }
 
 static void
-data_source_target(void *data,
+dnd_drag_update_surface(struct dnd_drag *dnd_drag)
-		   struct wl_data_source *source, const char *mime_type)
 {
-	struct dnd_drag *dnd_drag = data;
 	struct dnd *dnd = dnd_drag->dnd;
 	cairo_surface_t *surface;
 	struct wl_buffer *buffer;
 
-	dnd_drag->mime_type = mime_type;
+	if (dnd_drag->mime_type && dnd_drag->dnd_action)
-	if (mime_type)
 		surface = dnd_drag->opaque;
 	else
 		surface = dnd_drag->translucent;
@@ -287,6 +285,16 @@ data_source_target(void *data,
 	wl_surface_commit(dnd_drag->drag_surface);
 }
 
+static void
+data_source_target(void *data,
+		   struct wl_data_source *source, const char *mime_type)
+{
+	struct dnd_drag *dnd_drag = data;
+
+	dnd_drag->mime_type = mime_type;
+	dnd_drag_update_surface(dnd_drag);
+}
+
 static void
 data_source_send(void *data, struct wl_data_source *source,
 		 const char *mime_type, int32_t fd)
@@ -360,12 +368,22 @@ data_source_dnd_finished(void *data, struct wl_data_source *source)
 	dnd_drag_destroy(dnd_drag);
 }
 
+static void
+data_source_action(void *data, struct wl_data_source *source, uint32_t dnd_action)
+{
+	struct dnd_drag *dnd_drag = data;
+
+	dnd_drag->dnd_action = dnd_action;
+	dnd_drag_update_surface(dnd_drag);
+}
+
 static const struct wl_data_source_listener data_source_listener = {
 	data_source_target,
 	data_source_send,
 	data_source_cancelled,
 	data_source_dnd_drop_performed,
 	data_source_dnd_finished,
+	data_source_action,
 };
 
 static cairo_surface_t *
@@ -428,6 +446,8 @@ create_drag_source(struct dnd *dnd,
 		dnd_drag->item = item;
 		dnd_drag->x_offset = x - item->x;
 		dnd_drag->y_offset = y - item->y;
+		dnd_drag->dnd_action = WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE;
+		dnd_drag->mime_type = NULL;
 
 		for (i = 0; i < ARRAY_LENGTH(dnd->items); i++) {
 			if (item == dnd->items[i]){
@@ -456,6 +476,12 @@ create_drag_source(struct dnd *dnd,
 					     text_mime_type);
 		}
 
+		if (display_get_data_device_manager_version(display) >=
+		    WL_DATA_SOURCE_SET_ACTIONS_SINCE_VERSION) {
+			wl_data_source_set_actions(dnd_drag->data_source,
+						   WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE);
+		}
+
 		wl_data_device_start_drag(input_get_data_device(input),
 					  dnd_drag->data_source,
 					  window_get_wl_surface(dnd->window),

clients/window.c

@@ -3418,6 +3418,8 @@ struct data_offer {
 	int fd;
 	data_func_t func;
 	int32_t x, y;
+	uint32_t dnd_action;
+	uint32_t source_actions;
 	void *user_data;
 };
 
@@ -3431,8 +3433,26 @@ data_offer_offer(void *data, struct wl_data_offer *wl_data_offer, const char *ty
 	*p = strdup(type);
 }
 
+static void
+data_offer_source_actions(void *data, struct wl_data_offer *wl_data_offer, uint32_t source_actions)
+{
+	struct data_offer *offer = data;
+
+	offer->source_actions = source_actions;
+}
+
+static void
+data_offer_action(void *data, struct wl_data_offer *wl_data_offer, uint32_t dnd_action)
+{
+	struct data_offer *offer = data;
+
+	offer->dnd_action = dnd_action;
+}
+
 static const struct wl_data_offer_listener data_offer_listener = {
 	data_offer_offer,
+	data_offer_source_actions,
+	data_offer_action
 };
 
 static void
@@ -3496,6 +3516,14 @@ data_device_enter(void *data, struct wl_data_device *data_device,
 		*p = NULL;
 
 		types_data = input->drag_offer->types.data;
+
+		if (input->display->data_device_manager_version >=
+		    WL_DATA_OFFER_SET_ACTIONS_SINCE_VERSION) {
+			wl_data_offer_set_actions(offer,
+						  WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY |
+						  WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE,
+						  WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE);
+		}
 	} else {
 		input->drag_offer = NULL;
 		types_data = NULL;
@@ -5932,6 +5960,12 @@ display_exit(struct display *display)
 	display->running = 0;
 }
 
+int
+display_get_data_device_manager_version(struct display *display)
+{
+	return display->data_device_manager_version;
+}
+
 void
 keysym_modifiers_add(struct wl_array *modifiers_map,
 		     const char *name)

clients/window.h

@@ -175,6 +175,9 @@ display_run(struct display *d);
 void
 display_exit(struct display *d);
 
+int
+display_get_data_device_manager_version(struct display *d);
+
 enum cursor_type {
 	CURSOR_BOTTOM_LEFT,
 	CURSOR_BOTTOM_RIGHT,

src/compositor.h

@@ -321,6 +321,9 @@ struct weston_data_offer {
 	struct wl_resource *resource;
 	struct weston_data_source *source;
 	struct wl_listener source_destroy_listener;
+	uint32_t dnd_actions;
+	enum wl_data_device_manager_dnd_action preferred_dnd_action;
+	bool in_ask;
 };
 
 struct weston_data_source {
@@ -330,6 +333,9 @@ struct weston_data_source {
 	struct weston_data_offer *offer;
 	struct weston_seat *seat;
 	bool accepted;
+	bool actions_set;
+	uint32_t dnd_actions;
+	enum wl_data_device_manager_dnd_action current_dnd_action;
 
 	void (*accept)(struct weston_data_source *source,
 		       uint32_t serial, const char *mime_type);

src/data-device.c

@@ -56,6 +56,10 @@ struct weston_touch_drag {
 	struct weston_touch_grab grab;
 };
 
+#define ALL_ACTIONS (WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY | \
+		     WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE | \
+		     WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK)
+
 static void
 data_offer_accept(struct wl_client *client, struct wl_resource *resource,
 		  uint32_t serial, const char *mime_type)
@@ -95,6 +99,13 @@ data_offer_destroy(struct wl_client *client, struct wl_resource *resource)
 static void
 data_source_notify_finish(struct weston_data_source *source)
 {
+	if (source->offer->in_ask &&
+	    wl_resource_get_version(source->resource) >=
+	    WL_DATA_SOURCE_ACTION_SINCE_VERSION) {
+		wl_data_source_send_action(source->resource,
+					   source->current_dnd_action);
+	}
+
 	if (wl_resource_get_version(source->resource) >=
 	    WL_DATA_SOURCE_DND_FINISHED_SINCE_VERSION) {
 		wl_data_source_send_dnd_finished(source->resource);
@@ -103,6 +114,94 @@ data_source_notify_finish(struct weston_data_source *source)
 	source->offer = NULL;
 }
 
+static uint32_t
+data_offer_choose_action(struct weston_data_offer *offer)
+{
+	uint32_t available_actions, preferred_action = 0;
+	uint32_t source_actions, offer_actions;
+
+	if (wl_resource_get_version(offer->resource) >=
+	    WL_DATA_OFFER_ACTION_SINCE_VERSION) {
+		offer_actions = offer->dnd_actions;
+		preferred_action = offer->preferred_dnd_action;
+	} else {
+		offer_actions = WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY;
+	}
+
+	if (wl_resource_get_version(offer->source->resource) >=
+	    WL_DATA_SOURCE_ACTION_SINCE_VERSION)
+		source_actions = offer->source->dnd_actions;
+	else
+		source_actions = WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY;
+
+	available_actions = offer_actions & source_actions;
+
+	if (!available_actions)
+		return WL_DATA_DEVICE_MANAGER_DND_ACTION_NONE;
+
+	/* If the dest side has a preferred DnD action, use it */
+	if ((preferred_action & available_actions) != 0)
+		return preferred_action;
+
+	/* Use the first found action, in bit order */
+	return 1 << (ffs(available_actions) - 1);
+}
+
+static void
+data_offer_update_action(struct weston_data_offer *offer)
+{
+	uint32_t action;
+
+	if (!offer->source)
+		return;
+
+	action = data_offer_choose_action(offer);
+
+	if (offer->source->current_dnd_action == action)
+		return;
+
+	offer->source->current_dnd_action = action;
+
+	if (offer->in_ask)
+		return;
+
+	if (wl_resource_get_version(offer->source->resource) >=
+	    WL_DATA_SOURCE_ACTION_SINCE_VERSION)
+		wl_data_source_send_action(offer->source->resource, action);
+
+	if (wl_resource_get_version(offer->resource) >=
+	    WL_DATA_OFFER_ACTION_SINCE_VERSION)
+		wl_data_offer_send_action(offer->resource, action);
+}
+
+static void
+data_offer_set_actions(struct wl_client *client,
+		       struct wl_resource *resource,
+		       uint32_t dnd_actions, uint32_t preferred_action)
+{
+	struct weston_data_offer *offer = wl_resource_get_user_data(resource);
+
+	if (dnd_actions & ~ALL_ACTIONS) {
+		wl_resource_post_error(offer->resource,
+				       WL_DATA_OFFER_ERROR_INVALID_ACTION_MASK,
+				       "invalid action mask %x", dnd_actions);
+		return;
+	}
+
+	if (preferred_action &&
+	    (!(preferred_action & dnd_actions) ||
+	     __builtin_popcount(preferred_action) > 1)) {
+		wl_resource_post_error(offer->resource,
+				       WL_DATA_OFFER_ERROR_INVALID_ACTION,
+				       "invalid action %x", preferred_action);
+		return;
+	}
+
+	offer->dnd_actions = dnd_actions;
+	offer->preferred_dnd_action = preferred_action;
+	data_offer_update_action(offer);
+}
+
 static void
 data_offer_finish(struct wl_client *client, struct wl_resource *resource)
 {
@@ -122,6 +221,17 @@ data_offer_finish(struct wl_client *client, struct wl_resource *resource)
 		return;
 	}
 
+	switch (offer->source->current_dnd_action) {
+	case WL_DATA_DEVICE_MANAGER_DND_ACTION_NONE:
+	case WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK:
+		wl_resource_post_error(offer->resource,
+				       WL_DATA_OFFER_ERROR_INVALID_OFFER,
+				       "offer finished with an invalid action");
+		return;
+	default:
+		break;
+	}
+
 	data_source_notify_finish(offer->source);
 }
 
@@ -130,6 +240,7 @@ static const struct wl_data_offer_interface data_offer_interface = {
 	data_offer_receive,
 	data_offer_destroy,
 	data_offer_finish,
+	data_offer_set_actions,
 };
 
 static void
@@ -196,6 +307,9 @@ weston_data_source_send_offer(struct weston_data_source *source,
 	wl_resource_set_implementation(offer->resource, &data_offer_interface,
 				       offer, destroy_data_offer);
 
+	offer->in_ask = false;
+	offer->dnd_actions = 0;
+	offer->preferred_dnd_action = WL_DATA_DEVICE_MANAGER_DND_ACTION_NONE;
 	offer->source = source;
 	offer->source_destroy_listener.notify = destroy_offer_data_source;
 	wl_signal_add(&source->destroy_signal,
@@ -208,6 +322,7 @@ weston_data_source_send_offer(struct weston_data_source *source,
 
 	source->offer = offer;
 	source->accepted = false;
+	data_offer_update_action(offer);
 
 	return offer->resource;
 }
@@ -234,9 +349,44 @@ data_source_destroy(struct wl_client *client, struct wl_resource *resource)
 	wl_resource_destroy(resource);
 }
 
+static void
+data_source_set_actions(struct wl_client *client,
+			struct wl_resource *resource,
+			uint32_t dnd_actions)
+{
+	struct weston_data_source *source =
+		wl_resource_get_user_data(resource);
+
+	if (source->actions_set) {
+		wl_resource_post_error(source->resource,
+				       WL_DATA_SOURCE_ERROR_INVALID_ACTION_MASK,
+				       "cannot set actions more than once");
+		return;
+	}
+
+	if (dnd_actions & ~ALL_ACTIONS) {
+		wl_resource_post_error(source->resource,
+				       WL_DATA_SOURCE_ERROR_INVALID_ACTION_MASK,
+				       "invalid action mask %x", dnd_actions);
+		return;
+	}
+
+	if (source->seat) {
+		wl_resource_post_error(source->resource,
+				       WL_DATA_SOURCE_ERROR_INVALID_ACTION_MASK,
+				       "invalid action change after "
+				       "wl_data_device.start_drag");
+		return;
+	}
+
+	source->dnd_actions = dnd_actions;
+	source->actions_set = true;
+}
+
 static struct wl_data_source_interface data_source_interface = {
 	data_source_offer,
-	data_source_destroy
+	data_source_destroy,
+	data_source_set_actions
 };
 
 static void
@@ -378,6 +528,12 @@ weston_drag_set_focus(struct weston_drag *drag,
 							       resource);
 		if (offer_resource == NULL)
 			return;
+
+		if (wl_resource_get_version (offer_resource) >=
+		    WL_DATA_OFFER_SOURCE_ACTIONS_SINCE_VERSION) {
+			wl_data_offer_send_source_actions (offer_resource,
+			                                   drag->data_source->dnd_actions);
+		}
 	}
 
 	wl_data_device_send_enter(resource, serial, view->surface->resource,
@@ -475,13 +631,18 @@ drag_grab_button(struct weston_pointer_grab *grab,
 	    pointer->grab_button == button &&
 	    state == WL_POINTER_BUTTON_STATE_RELEASED) {
 		if (drag->base.focus_resource &&
-		    data_source->accepted) {
+		    data_source->accepted &&
+		    data_source->current_dnd_action) {
 			wl_data_device_send_drop(drag->base.focus_resource);
 
 			if (wl_resource_get_version(data_source->resource) >=
 			    WL_DATA_SOURCE_DND_DROP_PERFORMED_SINCE_VERSION)
 				wl_data_source_send_dnd_drop_performed(data_source->resource);
 
+			data_source->offer->in_ask =
+				data_source->current_dnd_action ==
+				WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK;
+
 			data_source->seat = NULL;
 		} else if (wl_resource_get_version(data_source->resource) >=
 			   WL_DATA_SOURCE_DND_FINISHED_SINCE_VERSION) {
@@ -912,13 +1073,23 @@ data_device_set_selection(struct wl_client *client,
 			  struct wl_resource *resource,
 			  struct wl_resource *source_resource, uint32_t serial)
 {
+	struct weston_data_source *source;
+
 	if (!source_resource)
 		return;
 
+	source = wl_resource_get_user_data(source_resource);
+
+	if (source->actions_set) {
+		wl_resource_post_error(source_resource,
+				       WL_DATA_SOURCE_ERROR_INVALID_SOURCE,
+				       "cannot set drag-and-drop source as selection");
+		return;
+	}
+
 	/* FIXME: Store serial and check against incoming serial here. */
 	weston_seat_set_selection(wl_resource_get_user_data(resource),
-				  wl_resource_get_user_data(source_resource),
+				  source, serial);
-				  serial);
 }
 static void
 data_device_release(struct wl_client *client, struct wl_resource *resource)
@@ -998,6 +1169,9 @@ create_data_source(struct wl_client *client,
 	source->offer = NULL;
 	source->accepted = false;
 	source->seat = NULL;
+	source->actions_set = false;
+	source->dnd_actions = 0;
+	source->current_dnd_action = WL_DATA_DEVICE_MANAGER_DND_ACTION_NONE;
 
 	wl_array_init(&source->mime_types);