window layouter: keyboard actions

This patch adds support for manipulating the window layout with keyboard
actions. It supports the toggling of fullscreen (aka maximize), the
raising of the currently focused window, and the focusing the next/previous
window.

repos/gems/src/app/floating_window_layouter/README

@@ -0,0 +1,84 @@
+The window-layouter component complements the window manager (wm) with the
+policy of how windows are positioned on screen and how windows behave when the
+user interacts with window elements like the maximize button or the window
+title. Whereas the decorator defines how windows look, the layouter defines how
+they behave.
+
+By default, the window layouter presents each window as a floating window that
+can be positioned by dragging the window title, or resized by dragging the
+window border.
+
+
+Configurable window placement
+-----------------------------
+
+The policy of the window layouter can be adjusted via its configuration. For
+a given window label, the window's initial position and its maximized state
+can be defined as follows:
+
+! <config>
+!   <policy label="mupdf" maximized="yes"/>
+!   <policy label="nit_fb" xpos="50" ypos="50"/>
+! </config>
+
+
+Keyboard shortcuts
+------------------
+
+The window layouter is able to respond to key sequences. However, normally,
+the layouter is not a regular nitpicker client but receives only those
+input events that refer to the window decorations. It never owns the keyboard
+focus. In order to propagate global key sequences to the layouter, nitpicker
+must be explicitly configured to direct key sequences initiated with certain
+keys to the decorator. For example, the following nitpicker configuration
+routes key sequences starting with the left windows key to the decorator. The
+window manager, in turn, forwards those events to the layouter.
+
+! <start name="nitpicker">
+!   ...
+!   <config>
+!     ...
+!     <global-key name="KEY_LEFTMETA" label="wm -> decorator" />
+!     ...
+!   </config>
+!   ...
+! </start>
+
+The response of the window layouter to key sequences can be expressed in the
+layouter configuration as follows:
+
+! <config>
+!   <press key="KEY_LEFTMETA">
+!     <press key="KEY_TAB"              action="next_window">
+!       <release key="KEY_TAB">
+!         <release key="KEY_LEFTMETA"   action="raise_window"/>
+!       </release>
+!     </press>
+!     <press key="KEY_LEFTSHIFT">
+!       <press key="KEY_TAB"            action="prev_window">
+!         <release key="KEY_TAB">
+!           <release key="KEY_LEFTMETA" action="raise_window"/>
+!         </release>
+!       </press>
+!     </press>
+!     <press key="KEY_ENTER"            action="toggle_fullscreen"/>
+!   </press>
+! </config>
+
+Each '<press>' node defines the policy when the specified 'key' is pressed.
+If can be equipped with an 'action' attribute that triggers a window action.
+The supported window actions are:
+
+:next_window:       Focus the next window in the focus history.
+:prev_window:       Focus the previous window in the focus history.
+:raise_window:      Bring the focused window to the front.
+:toggle_fullscreen: Maximize/unmaximize the focused window.
+
+By nesting '<press>' nodes, actions can be tied to key sequences. In the
+example above, the 'next_window' action is executed only if TAB is pressed
+while the left windows-key is kept pressed. Furthermore, key sequences can
+contain specific release events. In the example above, the release of the left
+windows key brings the focused window to front, but only if TAB was pressed
+before.
+
+

repos/gems/src/app/floating_window_layouter/focus_history.h

@@ -0,0 +1,123 @@
+/*
+ * \brief  Focus history, used for swiching between recently focused windows
+ * \author Norman Feske
+ * \date   2016-02-02
+ */
+
+/*
+ * Copyright (C) 2016 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _FOCUS_HISTORY_H_
+#define _FOCUS_HISTORY_H_
+
+/* Genode includes */
+#include <util/list.h>
+
+namespace Floating_window_layouter { class Focus_history; }
+
+
+class Floating_window_layouter::Focus_history
+{
+	public:
+
+		struct Entry : Genode::List<Entry>::Element
+		{
+			Focus_history  &focus_history;
+			Window_id const window_id;
+
+			Entry(Focus_history &focus_history, Window_id window_id);
+
+			inline ~Entry();
+		};
+
+	private:
+
+		Genode::List<Entry> _entries;
+
+		Entry *_lookup(Window_id window_id)
+		{
+			for (Entry *e = _entries.first(); e; e = e->next())
+				if (e->window_id == window_id)
+					return e;
+
+			return nullptr;
+		}
+
+		void _remove_if_present(Entry &entry)
+		{
+			_entries.remove(&entry);
+		}
+
+	public:
+
+		void focus(Window_id window_id)
+		{
+			Entry * const entry = _lookup(window_id);
+			if (!entry) {
+				PWRN("unexpected lookup failure for focus history entry");
+				return;
+			}
+
+			_remove_if_present(*entry);
+
+			/* insert entry at the beginning (most recently focused) */
+			_entries.insert(entry);
+		}
+
+		Window_id next(Window_id window_id)
+		{
+			Entry * const first = _entries.first();
+			if (!first)
+				return Window_id();
+
+			Entry * const entry = _lookup(window_id);
+			if (!entry)
+				return Window_id();
+
+			Entry * const next  = entry->next();
+			return next ? next->window_id : first->window_id;
+		}
+
+		Window_id prev(Window_id window_id)
+		{
+			Entry *curr = _entries.first();
+			if (!curr)
+				return Window_id();
+
+			/* if argument refers to the first window, cycle to the last one */
+			if (curr->window_id == window_id) {
+
+				/* determine last list element */
+				for (; curr->next(); curr = curr->next());
+				return curr->window_id;
+			}
+
+			/* traverse list, looking for the predecessor of the window */
+			for (; curr->next(); curr = curr->next())
+				if (curr->next()->window_id == window_id)
+					return curr->window_id;
+
+			return Window_id();
+		}
+};
+
+
+Floating_window_layouter::Focus_history::Entry::Entry(Focus_history &focus_history,
+                                                      Window_id window_id)
+:
+	focus_history(focus_history), window_id(window_id)
+{
+	focus_history._entries.insert(this);
+}
+
+
+Floating_window_layouter::Focus_history::Entry::~Entry()
+{
+	focus_history._remove_if_present(*this);
+}
+
+#endif /* _FOCUS_HISTORY_H_ */

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

@@ -65,6 +65,8 @@ struct Floating_window_layouter::Main : Operations
 
 	List<Window> windows;
 
+	Focus_history focus_history;
+
 	Window *lookup_window_by_id(Window_id const id)
 	{
 		for (Window *w = windows.first(); w; w = w->next())
@@ -95,7 +97,7 @@ struct Floating_window_layouter::Main : Operations
 			fn(*w);
 	}
 
-	User_state _user_state { *this };
+	User_state _user_state { *this, focus_history };
 
 
 	/**************************
@@ -129,6 +131,7 @@ struct Floating_window_layouter::Main : Operations
 
 	void focus(Window_id id) override
 	{
+		generate_window_layout_model();
 		generate_focus_model();
 	}
 
@@ -354,7 +357,8 @@ void Floating_window_layouter::Main::import_window_list(Xml_node window_list_xml
 
 			Window *win = lookup_window_by_id(id);
 			if (!win) {
-				win = new (env()->heap()) Window(id, maximized_window_geometry);
+				win = new (env()->heap())
+					Window(id, maximized_window_geometry, focus_history);
 				windows.insert(win);
 
 				Point initial_position(150*id % 800, 30 + (100*id % 500));

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

@@ -73,6 +73,8 @@ class Floating_window_layouter::User_state
 
 		Operations &_operations;
 
+		Focus_history &_focus_history;
+
 		bool _is_key(Input::Event const &ev) const
 		{
 			if (ev.type() != Input::Event::PRESS
@@ -107,6 +109,7 @@ class Floating_window_layouter::User_state
 
 				_dragged_window_id = _hovered_window_id;
 				_focused_window_id = _hovered_window_id;
+				_focus_history.focus(_focused_window_id);
 
 				_operations.toggle_fullscreen(_hovered_window_id);
 				return;
@@ -118,6 +121,7 @@ class Floating_window_layouter::User_state
 			if (_focused_window_id != _hovered_window_id) {
 
 				_focused_window_id = _hovered_window_id;
+				_focus_history.focus(_focused_window_id);
 
 				_operations.to_front(_hovered_window_id);
 				_operations.focus(_hovered_window_id);
@@ -129,7 +133,10 @@ class Floating_window_layouter::User_state
 
 	public:
 
-		User_state(Operations &operations) : _operations(operations) { }
+		User_state(Operations &operations, Focus_history &focus_history)
+		:
+			_operations(operations), _focus_history(focus_history)
+		{ }
 
 		void handle_input(Input::Event const events[], unsigned num_events,
 		                  Xml_node const &config)
@@ -181,6 +188,7 @@ class Floating_window_layouter::User_state
 			 && _hovered_window_id != last_hovered_window_id) {
 
 				_focused_window_id = _hovered_window_id;
+				_focus_history.focus(_focused_window_id);
 				_operations.focus(_focused_window_id);
 			}
 		}
@@ -220,6 +228,7 @@ void Floating_window_layouter::User_state::_handle_event(Input::Event const &e,
 	if (e.type() == Input::Event::PRESS)   _key_cnt++;
 	if (e.type() == Input::Event::RELEASE) _key_cnt--;
 
+	/* handle pointer click */
 	if (e.type()    == Input::Event::PRESS
 	 && e.keycode() == Input::BTN_LEFT
 	 && _key_cnt    == 1) {
@@ -276,15 +285,43 @@ void Floating_window_layouter::User_state::_handle_event(Input::Event const &e,
 		                          _pointer_clicked, _pointer_curr);
 	}
 
+	/* handle key sequences */
 	if (_is_key(e)) {
 
 		if (e.type() == Input::Event::PRESS && _key_cnt == 1)
 			_key_sequence_tracker.reset();
 
 		_key_sequence_tracker.apply(e, config, [&] (Action action) {
-			PINF("trigger action %d", action.type());
+
+			switch (action.type()) {
+
+			case Action::TOGGLE_FULLSCREEN:
+				_operations.toggle_fullscreen(_focused_window_id);
+				return;
+
+			case Action::RAISE_WINDOW:
+				_operations.to_front(_focused_window_id);
+				return;
+
+			case Action::NEXT_WINDOW:
+				_focused_window_id = _focus_history.next(_focused_window_id);
+				_operations.focus(_focused_window_id);
+				return;
+
+			case Action::PREV_WINDOW:
+				_focused_window_id = _focus_history.prev(_focused_window_id);
+				_operations.focus(_focused_window_id);
+				return;
+
+			default:
+				PWRN("action %d unhanded", action.type());
+			}
 		});
 	}
+
+	/* update focus history after key/button action is completed */
+	if (e.type() == Input::Event::RELEASE && _key_cnt == 0)
+		_focus_history.focus(_focused_window_id);
 }
 
 #endif /* _USER_STATE_H_ */

repos/gems/src/app/floating_window_layouter/window.h

@@ -16,6 +16,7 @@
 
 /* local includes */
 #include "types.h"
+#include "focus_history.h"
 
 namespace Floating_window_layouter { class Window; }
 
@@ -113,6 +114,8 @@ class Floating_window_layouter::Window : public List<Window>::Element
 		 */
 		unsigned _topped_cnt = 0;
 
+		Focus_history::Entry _focus_history_entry;
+
 		bool _drag_left_border   = false;
 		bool _drag_right_border  = false;
 		bool _drag_top_border    = false;
@@ -176,9 +179,11 @@ class Floating_window_layouter::Window : public List<Window>::Element
 
 	public:
 
-		Window(Window_id id, Rect &maximized_geometry)
+		Window(Window_id id, Rect &maximized_geometry,
+		       Focus_history &focus_history)
 		:
-			_id(id), _maximized_geometry(maximized_geometry)
+			_id(id), _maximized_geometry(maximized_geometry),
+			_focus_history_entry(focus_history, _id)
 		{ }
 
 		bool has_id(Window_id id) const { return id == _id; }