Implement tabbing between fields in GUI2 dialogs

Unfortunately, each dialog currently needs to manually set up the tab
order, but this is at least better than nothing.

changelog

@@ -1,4 +1,6 @@
 Version 1.13.8+dev:
+ * User Interface:
+   * Enable the use of tab to switch between text fields in most dialogs.
 
 Version 1.13.8:
   * Campaigns:

src/gui/core/event/distributor.cpp

@@ -551,7 +551,7 @@ distributor::distributor(widget& owner,
 	, tooltip_(0)
 	, help_popup_(0)
 #endif
-	, keyboard_focus_(0)
+	, keyboard_focus_(nullptr)
 	, keyboard_focus_chain_()
 {
 	if(SDL_WasInit(SDL_INIT_TIMER) == 0) {
@@ -589,6 +589,11 @@ void distributor::initialize_state()
 	init_mouse_location();
 }
 
+widget* distributor::keyboard_focus() const
+{
+	return keyboard_focus_;
+}
+
 void distributor::keyboard_capture(widget* widget)
 {
 	if(keyboard_focus_) {

src/gui/core/event/distributor.hpp

@@ -297,6 +297,11 @@ public:
 	 */
 	void keyboard_remove_from_chain(widget* widget);
 
+	/**
+	 * Return the widget currently capturing keyboard input.
+	 */
+	widget* keyboard_focus() const;
+
 private:
 	class layer : public video2::draw_layering
 	{

src/gui/dialogs/editor/custom_tod.cpp

@@ -123,6 +123,9 @@ void custom_tod::pre_show(window& window)
 		{"sound", tod_getter_sound}
 	};
 
+	window.add_to_tab_order(find_widget<text_box>(&window, "tod_name", false, false));
+	window.add_to_tab_order(find_widget<text_box>(&window, "tod_id", false, false));
+
 	for(const auto& data : metadata_stuff) {
 		find_widget<text_box>(&window, "path_" + data.first, false).set_active(false);
 

src/gui/dialogs/editor/edit_label.cpp

@@ -16,7 +16,10 @@
 
 #include "gui/dialogs/editor/edit_label.hpp"
 
+#include "gui/auxiliary/find_widget.hpp"
 #include "gui/widgets/settings.hpp"
+#include "gui/widgets/text_box.hpp"
+#include "gui/widgets/window.hpp"
 
 #include "utils/functional.hpp"
 
@@ -81,6 +84,12 @@ editor_edit_label::editor_edit_label(std::string& text,
 	register_color_component("slider_blue", &color_t::b);
 }
 
+void editor_edit_label::pre_show(window& win)
+{
+	win.add_to_tab_order(find_widget<text_box>(&win, "label", false, false));
+	win.add_to_tab_order(find_widget<text_box>(&win, "category", false, false));
+}
+
 void editor_edit_label::register_color_component(std::string widget_id, uint8_t color_t::* component) {
 	register_integer(widget_id, true,
 					 std::bind(&editor_edit_label::load_color_component, this, component),

src/gui/dialogs/editor/edit_label.hpp

@@ -62,6 +62,8 @@ private:
 	void register_color_component(std::string widget_id, uint8_t color_t::* component);
 	/** Inherited from modal_dialog, implemented by REGISTER_DIALOG. */
 	virtual const std::string& window_id() const override;
+	/** Inherited from modal_dialog. */
+	virtual void pre_show(window& window) override;
 };
 } // namespace dialogs
 } // namespace gui2

src/gui/dialogs/editor/edit_scenario.cpp

@@ -16,7 +16,10 @@
 
 #include "gui/dialogs/editor/edit_scenario.hpp"
 
+#include "gui/auxiliary/find_widget.hpp"
 #include "gui/widgets/settings.hpp"
+#include "gui/widgets/text_box.hpp"
+#include "gui/widgets/window.hpp"
 
 namespace gui2
 {
@@ -67,5 +70,13 @@ editor_edit_scenario::editor_edit_scenario(
 				  victory_when_enemies_defeated);
 	register_bool("random_start_time", true, random_start_time);
 }
+
+void editor_edit_scenario::pre_show(window& win)
+{
+	win.add_to_tab_order(find_widget<text_box>(&win, "id", false, false));
+	win.add_to_tab_order(find_widget<text_box>(&win, "name", false, false));
+	win.add_to_tab_order(find_widget<text_box>(&win, "description", false, false));
+}
+
 } // namespace dialogs
 } // namespace gui2

src/gui/dialogs/editor/edit_scenario.hpp

@@ -54,6 +54,8 @@ public:
 private:
 	/** Inherited from modal_dialog, implemented by REGISTER_DIALOG. */
 	virtual const std::string& window_id() const override;
+	/** Inherited from modal_dialog. */
+	virtual void pre_show(window& window) override;
 };
 } // namespace dialogs
 } // namespace gui2

src/gui/dialogs/editor/edit_side.cpp

@@ -87,6 +87,9 @@ void editor_edit_side::pre_show(window& window)
 	vision_group.add_member(&find_widget<toggle_button>(&window, "vision_null", false),   team::SHARE_VISION::NONE);
 
 	vision_group.set_member_states(share_vision_);
+
+	window.add_to_tab_order(find_widget<text_box>(&window, "team_name", false, false));
+	window.add_to_tab_order(find_widget<text_box>(&window, "user_team_name", false, false));
 }
 
 void editor_edit_side::post_show(window&)

src/gui/dialogs/lobby/player_info.cpp

@@ -112,6 +112,8 @@ void lobby_player_info::pre_show(window& window)
 
 	time_ = find_widget<text_box>(&window, "time", false, true);
 	reason_ = find_widget<text_box>(&window, "reason", false, true);
+	window.add_to_tab_order(reason_);
+	window.add_to_tab_order(time_);
 
 	find_widget<label>(&window, "location_info", false).set_label(loc.str());
 

src/gui/dialogs/multiplayer/mp_login.cpp

@@ -93,6 +93,9 @@ void mp_login::pre_show(window& win)
 
 		btn->set_retval(2);
 	}
+
+	win.add_to_tab_order(find_widget<text_box>(&win, "user_name", false, false));
+	win.add_to_tab_order(find_widget<text_box>(&win, "password", false, false));
 }
 
 void mp_login::post_show(window& win)

src/gui/widgets/window.cpp

@@ -389,10 +389,10 @@ window::window(CVideo& video,
 
 	connect_signal<event::SDL_KEY_DOWN>(
 			std::bind(
-					&window::signal_handler_sdl_key_down, this, _2, _3, _5),
+					&window::signal_handler_sdl_key_down, this, _2, _3, _5, _6, true),
 			event::dispatcher::back_post_child);
 	connect_signal<event::SDL_KEY_DOWN>(std::bind(
-			&window::signal_handler_sdl_key_down, this, _2, _3, _5));
+			&window::signal_handler_sdl_key_down, this, _2, _3, _5, _6, false));
 
 	connect_signal<event::MESSAGE_SHOW_TOOLTIP>(
 			std::bind(&window::signal_handler_message_show_tooltip,
@@ -1340,6 +1340,22 @@ void window::remove_from_keyboard_chain(widget* widget)
 	event_distributor_->keyboard_remove_from_chain(widget);
 }
 
+void window::add_to_tab_order(widget* widget, int at)
+{
+	if(std::find(tab_order.begin(), tab_order.end(), widget) != tab_order.end()) {
+		return;
+	}
+	assert(event_distributor_);
+	if(tab_order.empty() && !event_distributor_->keyboard_focus()) {
+		keyboard_capture(widget);
+	}
+	if(at < 0 || at >= static_cast<int>(tab_order.size())) {
+		tab_order.push_back(widget);
+	} else {
+		tab_order.insert(tab_order.begin() + at, widget);
+	}
+}
+
 void window::signal_handler_sdl_video_resize(const event::ui_event event,
 											  bool& handled,
 											  const point& new_size)
@@ -1366,9 +1382,19 @@ void window::signal_handler_click_dismiss(const event::ui_event event,
 	handled = halt = click_dismiss(mouse_button_mask);
 }
 
+static bool is_active(const widget* wgt)
+{
+	if(const styled_widget* control = dynamic_cast<const styled_widget*>(wgt)) {
+		return control->get_active() && control->get_visible() == window::visibility::visible;
+	}
+	return false;
+}
+
 void window::signal_handler_sdl_key_down(const event::ui_event event,
 										  bool& handled,
-										  SDL_Keycode key)
+										  const SDL_Keycode key,
+										  const SDL_Keymod mod,
+										  bool handle_tab)
 {
 	DBG_GUI_E << LOG_HEADER << ' ' << event << ".\n";
 
@@ -1380,6 +1406,29 @@ void window::signal_handler_sdl_key_down(const event::ui_event event,
 		handled = true;
 	} else if(key == SDLK_SPACE) {
 		handled = click_dismiss(0);
+	} else if(handle_tab && !tab_order.empty() && key == SDLK_TAB) {
+		assert(event_distributor_);
+		widget* focus = event_distributor_->keyboard_focus();
+		auto iter = std::find(tab_order.begin(), tab_order.end(), focus);
+		do {
+			if(mod & KMOD_SHIFT) {
+				if(iter == tab_order.begin()) {
+					iter = tab_order.end();
+				}
+				iter--;
+			} else {
+				if(iter == tab_order.end()) {
+					iter = tab_order.begin();
+				} else {
+					iter++;
+					if(iter == tab_order.end()) {
+						iter = tab_order.begin();
+					}
+				}
+			}
+		} while(!is_active(*iter));
+		keyboard_capture(*iter);
+		handled = true;
 	}
 #ifdef DEBUG_WINDOW_LAYOUT_GRAPHS
 	if(key == SDLK_F12) {

src/gui/widgets/window.hpp

@@ -643,6 +643,9 @@ private:
 	/** List of the widgets, whose size are linked together. */
 	std::map<std::string, linked_size> linked_size_;
 
+	/** List of widgets in the tabbing order. */
+	std::vector<widget*> tab_order;
+
 	/**
 	 * Layouts the window.
 	 *
@@ -749,6 +752,13 @@ public:
 	 */
 	void remove_from_keyboard_chain(widget* widget);
 
+	/**
+	 * Add the widget to the tabbing order
+	 * @param widget              The widget to be added to the tabbing order
+	 * @param at                  A hint for where to place the widget in the tabbing order
+	 */
+	void add_to_tab_order(widget* widget, int at = -1);
+
 private:
 	/***** ***** ***** signal handlers ***** ****** *****/
 
@@ -771,7 +781,9 @@ private:
 
 	void signal_handler_sdl_key_down(const event::ui_event event,
 									 bool& handled,
-									 const SDL_Keycode key);
+									 const SDL_Keycode key,
+									 const SDL_Keymod mod,
+									 bool handle_tab);
 
 	void signal_handler_message_show_tooltip(const event::ui_event event,
 											 bool& handled,