Prevent cursor based region-snapping when starting a move with A-Left

When wanting to snap to a region when starting the move
operation with A-Left (or a similar mousebind which includes a
modifier), the modifier - or another one - must be pressed again.

Fixes #761

include/labwc.h

@@ -164,6 +164,8 @@ struct seat {
 	/* Private use by regions.c */
 	struct region *region_active;
 	struct region_overlay region_overlay;
+	/* Used to prevent region snapping when starting a move with A-Left */
+	bool region_prevent_snap;
 
 	struct wl_client *active_client_while_inhibited;
 	struct wl_list inputs;

include/regions.h

@@ -33,8 +33,8 @@ struct region_overlay {
 	};
 };
 
-/* Can be used as a cheap check to detect if there are any regions configured */
-bool regions_available(void);
+/* Returns true if we should show the region overlay or snap to region */
+bool regions_should_snap(struct server *server);
 
 /**
  * regions_reconfigure*() - re-initializes all regions from struct rc.

src/cursor.c

@@ -190,17 +190,14 @@ process_cursor_move(struct server *server, uint32_t time)
 	view_move(view, dx, dy);
 
 	/* Region overlay */
-	if (!regions_available()) {
+	if (!regions_should_snap(server)) {
 		return;
 	}
-	struct wlr_keyboard *keyboard = &server->seat.keyboard_group->keyboard;
-	if (keyboard_any_modifiers_pressed(keyboard)) {
-		struct region *region = regions_from_cursor(server);
-		if (region) {
-			regions_show_overlay(view, &server->seat, region);
-		} else {
-			regions_hide_overlay(&server->seat);
-		}
+	struct region *region = regions_from_cursor(server);
+	if (region) {
+		regions_show_overlay(view, &server->seat, region);
+	} else {
+		regions_hide_overlay(&server->seat);
 	}
 }
 

src/interactive.c

@@ -58,6 +58,11 @@ interactive_begin(struct view *view, enum input_mode mode, uint32_t edges)
 			/* Store natural geometry at start of move */
 			view_store_natural_geometry(view);
 		}
+
+		/* Prevent region snapping when just moving via A-Left mousebind */
+		struct wlr_keyboard *keyboard = &seat->keyboard_group->keyboard;
+		seat->region_prevent_snap = keyboard_any_modifiers_pressed(keyboard);
+
 		cursor_set(seat, LAB_CURSOR_GRAB);
 		break;
 	case LAB_INPUT_STATE_RESIZE:
@@ -137,20 +142,15 @@ snap_to_edge(struct view *view)
 static bool
 snap_to_region(struct view *view)
 {
-	if (!regions_available()) {
+	if (!regions_should_snap(view->server)) {
 		return false;
 	}
 
-	struct wlr_keyboard *keyboard =
-		&view->server->seat.keyboard_group->keyboard;
-
-	if (keyboard_any_modifiers_pressed(keyboard)) {
-		struct region *region = regions_from_cursor(view->server);
-		if (region) {
-			view_snap_to_region(view, region,
-				/*store_natural_geometry*/ false);
-			return true;
-		}
+	struct region *region = regions_from_cursor(view->server);
+	if (region) {
+		view_snap_to_region(view, region,
+			/*store_natural_geometry*/ false);
+		return true;
 	}
 	return false;
 }
@@ -159,11 +159,8 @@ void
 interactive_finish(struct view *view)
 {
 	if (view->server->grabbed_view == view) {
-		enum input_mode mode = view->server->input_mode;
 		regions_hide_overlay(&view->server->seat);
-		view->server->input_mode = LAB_INPUT_STATE_PASSTHROUGH;
-		view->server->grabbed_view = NULL;
-		if (mode == LAB_INPUT_STATE_MOVE) {
+		if (view->server->input_mode == LAB_INPUT_STATE_MOVE) {
 			if (!snap_to_region(view)) {
 				if (!snap_to_edge(view)) {
 					/* Reset tiled state if not snapped */
@@ -171,6 +168,10 @@ interactive_finish(struct view *view)
 				}
 			}
 		}
+
+		view->server->input_mode = LAB_INPUT_STATE_PASSTHROUGH;
+		view->server->grabbed_view = NULL;
+
 		/* Update focus/cursor image */
 		cursor_update_focus(view->server);
 	}

src/keyboard.c

@@ -56,6 +56,11 @@ keyboard_modifiers_notify(struct wl_listener *listener, void *data)
 	struct wlr_keyboard_key_event *event = data;
 	struct wlr_keyboard *wlr_keyboard = keyboard->wlr_keyboard;
 
+	if (server->input_mode == LAB_INPUT_STATE_MOVE) {
+		/* Any change to the modifier state re-enable region snap */
+		seat->region_prevent_snap = false;
+	}
+
 	if (server->osd_state.cycle_view || server->grabbed_view
 			|| seat->workspace_osd_shown_by_modifier) {
 		if (event->state == WL_KEYBOARD_KEY_STATE_RELEASED

src/regions.c

@@ -17,9 +17,16 @@
 #include "view.h"
 
 bool
-regions_available(void)
+regions_should_snap(struct server *server)
 {
-	return !wl_list_empty(&rc.regions);
+	if (server->input_mode != LAB_INPUT_STATE_MOVE
+			|| wl_list_empty(&rc.regions)
+			|| server->seat.region_prevent_snap) {
+		return false;
+	}
+
+	struct wlr_keyboard *keyboard = &server->seat.keyboard_group->keyboard;
+	return keyboard_any_modifiers_pressed(keyboard);
 }
 
 static void