window_layouter: "pick_up" and "place_down" action

The new 'action' attribute values can be used to realize the
keyboard-based assignement of windows to screens. The "pick_up" action
(on a key press) selects the focused window to be held at the current
position until the "place_down" action is issued (by a key release).
While the focused window is held, "screen" actions can be executed
taking the picked up window to the selected screen.

Issue #5390

repos/gems/recipes/raw/motif_wm/layouter.config

@@ -26,12 +26,23 @@
 			</release>
 			<release key="KEY_SCREEN" action="raise_window"/>
 		</press>
-		<press key="KEY_LEFTSHIFT">
+		<press key="KEY_LEFTSHIFT" action="pick_up">
 			<press key="KEY_TAB" action="prev_window">
 				<release key="KEY_TAB">
 					<release key="KEY_SCREEN" action="raise_window"/>
 				</release>
 			</press>
+			<press key="KEY_1" action="screen" target="screen_1"/>
+			<press key="KEY_2" action="screen" target="screen_2"/>
+			<press key="KEY_3" action="screen" target="screen_3"/>
+			<press key="KEY_4" action="screen" target="screen_4"/>
+			<press key="KEY_5" action="screen" target="screen_5"/>
+			<press key="KEY_6" action="screen" target="screen_6"/>
+			<press key="KEY_7" action="screen" target="screen_7"/>
+			<press key="KEY_8" action="screen" target="screen_8"/>
+			<press key="KEY_9" action="screen" target="screen_9"/>
+			<press key="KEY_0" action="screen" target="screen_0"/>
+			<release key="KEY_LEFTSHIFT" action="place_down"/>
 		</press>
 		<press key="KEY_ENTER" action="toggle_fullscreen"/>
 		<press key="KEY_1"     action="screen" target="screen_1"/>

repos/gems/recipes/raw/window_layouter/window_layouter.config

@@ -26,12 +26,23 @@
 			</release>
 			<release key="KEY_SCREEN" action="raise_window"/>
 		</press>
-		<press key="KEY_LEFTSHIFT">
+		<press key="KEY_LEFTSHIFT" action="pick_up">
 			<press key="KEY_TAB" action="prev_window">
 				<release key="KEY_TAB">
 					<release key="KEY_SCREEN" action="raise_window"/>
 				</release>
 			</press>
+			<press key="KEY_1" action="screen" target="screen_1"/>
+			<press key="KEY_2" action="screen" target="screen_2"/>
+			<press key="KEY_3" action="screen" target="screen_3"/>
+			<press key="KEY_4" action="screen" target="screen_4"/>
+			<press key="KEY_5" action="screen" target="screen_5"/>
+			<press key="KEY_6" action="screen" target="screen_6"/>
+			<press key="KEY_7" action="screen" target="screen_7"/>
+			<press key="KEY_8" action="screen" target="screen_8"/>
+			<press key="KEY_9" action="screen" target="screen_9"/>
+			<press key="KEY_0" action="screen" target="screen_0"/>
+			<release key="KEY_LEFTSHIFT" action="place_down"/>
 		</press>
 		<press key="KEY_ENTER" action="toggle_fullscreen"/>
 		<press key="KEY_1"     action="screen" target="screen_1"/>

repos/gems/src/app/window_layouter/command.h

@@ -22,7 +22,7 @@ namespace Window_layouter { class Command; }
 struct Window_layouter::Command
 {
 	enum Type { NONE, NEXT_WINDOW, PREV_WINDOW, RAISE_WINDOW, TOGGLE_FULLSCREEN,
-	            NEXT_TAB, PREV_TAB, SCREEN, RELEASE_GRAB, };
+	            NEXT_TAB, PREV_TAB, SCREEN, RELEASE_GRAB, PICK_UP, PLACE_DOWN };
 
 	Type         type;
 	Target::Name target;
@@ -37,6 +37,8 @@ struct Window_layouter::Command
 			if (string == "toggle_fullscreen") return TOGGLE_FULLSCREEN;
 			if (string == "screen")            return SCREEN;
 			if (string == "release_grab")      return RELEASE_GRAB;
+			if (string == "pick_up")           return PICK_UP;
+			if (string == "place_down")        return PLACE_DOWN;
 
 			warning("cannot convert \"", string, "\" to action type");
 			return NONE;

repos/gems/src/app/window_layouter/main.cc

@@ -48,6 +48,7 @@ struct Window_layouter::Main : User_state::Action,
 	Timer::Connection _drop_timer { _env };
 
 	Drag _drag { };
+	Pick _pick { };
 
 	Signal_handler<Main> _drop_timer_handler {
 		_env.ep(), *this, &Main::_handle_drop_timer };
@@ -247,7 +248,7 @@ struct Window_layouter::Main : User_state::Action,
 					fn(from, to); }); });
 	}
 
-	void _retarget_window(Window_id id, Target const &from, Target const &to)
+	void _with_retargeted_window(Window_id id, Target const &to, auto const &fn)
 	{
 		_assign_list.for_each([&] (Assign &assign) {
 			Window *window_ptr = nullptr;
@@ -256,18 +257,44 @@ struct Window_layouter::Main : User_state::Action,
 					window_ptr = &member.window; });
 			if (window_ptr) {
 				assign.target_name = to.name;
-				window_ptr->warp(from.rect.at - to.rect.at);
+				fn(*window_ptr);
 			}
 		});
 	}
 
+	void _retarget_window(Window_id id, Target const &to)
+	{
+		_with_retargeted_window(id, to, [&] (Window &) { });
+	}
+
+	void _retarget_and_warp_window(Window_id id, Target const &from, Target const &to)
+	{
+		_with_retargeted_window(id, to, [&] (Window &window) {
+			window.warp(from.rect.at - to.rect.at); });
+	}
+
 	void screen(Target::Name const &name) override
 	{
+		auto with_visible_geometry = [&] (Rect orig, Area target_area, auto const &fn)
+		{
+			Area const overlap = Rect::intersect(orig, { { }, target_area }).area;
+			bool const visible = (overlap.w > 50) && (overlap.h > 50);
+
+			fn(visible ? orig : Rect { { }, orig.area });
+		};
+
+		/* change screen under picked window */
+		if (_pick.picked)
+			_with_target_change(_pick.window_id, name, [&] (Target const &, Target const &to) {
+				_with_retargeted_window(_pick.window_id, to, [&] (Window &window) {
+					with_visible_geometry(_pick.orig_geometry, to.rect.area, [&] (Rect rect) {
+						window.outer_geometry(rect); }); }); });
+
 		/* change of screen under the dragged window */
 		if (_drag.dragging())
 			_with_target_change(_drag.window_id, name, [&] (Target const &from, Target const &to) {
 				if (from.rect == to.rect)
-					_retarget_window(_drag.window_id, from, to); });
+					_retarget_window(_drag.window_id, to); });
 
 		/* repeated activation of screen moves focus to the screen */
 		bool already_visible = false;
@@ -287,6 +314,18 @@ struct Window_layouter::Main : User_state::Action,
 		_gen_rules_with_frontmost_screen(name);
 	}
 
+	void pick_up(Window_id id) override
+	{
+		_window_list.with_window(id, [&] (Window const &window) {
+			_pick = { .picked        = true,
+			          .window_id     = id,
+			          .orig_geometry = window.outer_geometry() };
+			to_front(id);
+		});
+	}
+
+	void place_down() override { _pick = { }; }
+
 	void drag(Window_id id, Window::Element element, Point clicked, Point curr) override
 	{
 		if (_drag.state == Drag::State::SETTLING)
@@ -362,7 +401,7 @@ struct Window_layouter::Main : User_state::Action,
 			_target_list.with_target_at(curr, [&] (Target const &pointed) {
 				_drag = { Drag::State::SETTLING, moving, id, curr, pointed.rect };
 				_with_target_change(id, pointed.name, [&] (Target const &from, Target const &to) {
-					_retarget_window(id, from, to); });
+					_retarget_and_warp_window(id, from, to); });
 			});
 		}
 

repos/gems/src/app/window_layouter/types.h

@@ -106,6 +106,13 @@ namespace Window_layouter {
 			return dragging() && id == window_id && moving;
 		}
 	};
+
+	struct Pick
+	{
+		bool      picked;
+		Window_id window_id;
+		Rect      orig_geometry;
+	};
 }
 
 #endif /* _TYPES_H_ */

repos/gems/src/app/window_layouter/user_state.h

@@ -34,6 +34,8 @@ class Window_layouter::User_state
 			virtual void to_front(Window_id) = 0;
 			virtual void drag(Window_id, Window::Element, Point clicked, Point curr) = 0;
 			virtual void finalize_drag(Window_id, Window::Element, Point clicked, Point final) = 0;
+			virtual void pick_up(Window_id) = 0;
+			virtual void place_down() = 0;
 			virtual void screen(Target::Name const &) = 0;
 		};
 
@@ -76,6 +78,8 @@ class Window_layouter::User_state
 		 */
 		bool _drag_init_done = false;
 
+		bool _picked_up = false;
+
 		/*
 		 * Pointer position at the beginning of a drag operation
 		 */
@@ -168,7 +172,7 @@ class Window_layouter::User_state
 
 		void hover(Window_id window_id, Window::Element element)
 		{
-			Window_id const last_hovered_window_id = _hovered_window_id;
+			Window_id const orig_hovered_window_id = _hovered_window_id;
 
 			_hovered_window_id = window_id;
 			_hovered_element   = element;
@@ -192,10 +196,11 @@ class Window_layouter::User_state
 				_initiate_drag(_hovered_window_id, _hovered_element);
 
 			/*
-			 * Let focus follows the pointer
+			 * Let focus follows the pointer, except while dragging or when
+			 * the focused window is currently picked up.
 			 */
-			if (!_drag_state && _hovered_window_id.valid()
-			 && _hovered_window_id != last_hovered_window_id) {
+			if (!_drag_state && !_picked_up && _hovered_window_id.valid()
+			 && _hovered_window_id != orig_hovered_window_id) {
 
 				_focused_window_id = _hovered_window_id;
 				_focus_history.focus(_focused_window_id);
@@ -329,6 +334,20 @@ void Window_layouter::User_state::_handle_event(Input::Event const &e,
 				_action.release_grab();
 				return;
 
+			case Command::PICK_UP:
+				if (_focused_window_id.value) {
+					_picked_up = true;
+					_action.pick_up(_focused_window_id);
+				}
+				return;
+
+			case Command::PLACE_DOWN:
+				if (_picked_up) {
+					_action.place_down();
+					_picked_up = false;
+				}
+				return;
+
 			default:
 				warning("command ", (int)command.type, " unhanded");
 			}