Outline focused element when Tab is pressed (#16798)

games/devtest/mods/testformspec/formspec.lua

@@ -323,6 +323,34 @@ local scroll_fs =
 --style_type[label;border=;bgcolor=]
 --label[0.75,2;Reset]
 
+local autoscroll_fs =
+	"label[0.5,0.5;Auto-Scroll Test - Tab through buttons to test auto-scroll centering]" ..
+	"label[0.5,1;Vertical scroll container:]" ..
+	"scroll_container[0.5,1.5;5.5,5;autoscroll_v;vertical]" ..
+		"button[0,0;5,1;asv_btn1;Button 1]" ..
+		"button[0,1;5,1;asv_btn2;Button 2]" ..
+		"button[0,2;5,1;asv_btn3;Button 3]" ..
+		"button[0,3;5,1;asv_btn4;Button 4]" ..
+		"button[0,4;5,1;asv_btn5;Button 5]" ..
+		"button[0,5;5,1;asv_btn6;Button 6]" ..
+		"button[0,6;5,1;asv_btn7;Button 7]" ..
+		"button[0,7;5,1;asv_btn8;Button 8]" ..
+		"button[0,8;5,1;asv_btn9;Button 9]" ..
+		"button[0,9;5,1;asv_btn10;Button 10]" ..
+	"scroll_container_end[]" ..
+	"scrollbaroptions[max=50]" ..
+	"scrollbar[5.8,1.5;0.3,5;vertical;autoscroll_v;0]" ..
+	"label[7,1;Horizontal scroll container:]" ..
+	"scroll_container[7,1.5;4.5,2;autoscroll_h;horizontal]" ..
+		"button[0,0;3,1;ash_btn1;Btn1]" ..
+		"button[3,0;3,1;ash_btn2;Btn2]" ..
+		"button[6,0;3,1;ash_btn3;Btn3]" ..
+		"button[9,0;3,1;ash_btn4;Btn4]" ..
+		"button[12,0;3,1;ash_btn5;Btn5]" ..
+	"scroll_container_end[]" ..
+	"scrollbaroptions[max=105]" ..
+	"scrollbar[7,2.7;4.5,0.3;horizontal;autoscroll_h;0]"
+
 local window = {
 	sizex = 12,
 	sizey = 13,
@@ -477,6 +505,10 @@ mouse control = true]
 		"formspec_version[7]size[12,13]" ..
 		scroll_fs,
 
+	-- Autoscroll
+		"formspec_version[7]size[12,13]" ..
+		autoscroll_fs,
+
 	-- Sound
 		[[
 			formspec_version[3]
@@ -528,7 +560,7 @@ local function show_test_formspec(pname)
 		page = page()
 	end
 
-	local fs = page .. "tabheader[0,0;11,0.65;maintabs;Real Coord,Styles,Noclip,Table,Hypertext,Tabs,Invs,Window,Anim,Model,ScrollC,Sound,Background,Unsized;" .. page_id .. ";false;false]"
+	local fs = page .. "tabheader[0,0;11,0.65;maintabs;Real Coord,Styles,Noclip,Table,Hypertext,Tabs,Invs,Window,Anim,Model,ScrollC,Autoscroll,Sound,Background,Unsized;" .. page_id .. ";false;false]"
 
 	core.show_formspec(pname, "testformspec:formspec", fs)
 end

src/gui/guiFormSpecMenu.cpp

@@ -3482,6 +3482,9 @@ void GUIFormSpecMenu::drawMenu()
 
 	updateSelectedItem();
 
+	// Auto-scroll to center focused element when Tab enables focus tracking
+	autoScroll();
+
 	video::IVideoDriver* driver = Environment->getVideoDriver();
 
 	/*
@@ -3613,6 +3616,27 @@ void GUIFormSpecMenu::drawMenu()
 			cursor_control->setActiveIcon(ECI_NORMAL);
 	}
 
+	// Draw white outline around keyboard-focused form elements.
+	const gui::IGUIElement *focused = Environment->getFocus();
+	if (focused && m_show_focus) {
+		core::rect<s32> rect = focused->getAbsoluteClippingRect();
+		const video::SColor white(255, 255, 255, 255);
+		const s32 border = 2;
+
+		driver->draw2DRectangle(white,
+			core::rect<s32>(rect.UpperLeftCorner.X, rect.UpperLeftCorner.Y,
+				rect.LowerRightCorner.X, rect.UpperLeftCorner.Y + border), nullptr);
+		driver->draw2DRectangle(white,
+			core::rect<s32>(rect.UpperLeftCorner.X, rect.LowerRightCorner.Y - border,
+				rect.LowerRightCorner.X, rect.LowerRightCorner.Y), nullptr);
+		driver->draw2DRectangle(white,
+			core::rect<s32>(rect.UpperLeftCorner.X, rect.UpperLeftCorner.Y,
+				rect.UpperLeftCorner.X + border, rect.LowerRightCorner.Y), nullptr);
+		driver->draw2DRectangle(white,
+			core::rect<s32>(rect.LowerRightCorner.X - border, rect.UpperLeftCorner.Y,
+				rect.LowerRightCorner.X, rect.LowerRightCorner.Y), nullptr);
+	}
+
 	m_tooltip_element->draw();
 
 	/*
@@ -3684,6 +3708,89 @@ void GUIFormSpecMenu::showTooltip(const std::wstring &text,
 	bringToFront(m_tooltip_element);
 }
 
+void GUIFormSpecMenu::autoScroll()
+{
+	gui::IGUIElement *focus = Environment->getFocus();
+	if (!m_show_focus || !focus)
+		return;
+
+	// Only process if focus changed or this is the first focus
+	if (focus == m_last_focused && m_last_focused != nullptr)
+		return;
+
+	bool first_focus = (m_last_focused == nullptr);
+	m_last_focused = focus;
+
+	// Find the scroll container that contains the focused element
+	for (const auto &cont : m_scroll_containers) {
+		if (!cont.second->isMyChild(focus))
+			continue;
+
+		gui::IGUIElement *clipper = cont.second->getParent();
+		if (!clipper)
+			break;
+
+		// Find scrollbars for this container
+		GUIScrollBar *scrollbar_v = nullptr;
+		GUIScrollBar *scrollbar_h = nullptr;
+		for (const auto &sb : m_scrollbars) {
+			if (sb.first.fname == cont.first) {
+				if (sb.second->isHorizontal())
+					scrollbar_h = sb.second;
+				else
+					scrollbar_v = sb.second;
+			}
+		}
+
+		core::rect<s32> clip = clipper->getAbsoluteClippingRect();
+		core::rect<s32> elem = focus->getAbsolutePosition();
+		f32 scrollfactor = cont.second->getScrollFactor();
+
+		if (scrollfactor == 0)
+			break;
+
+		// Handle vertical scrolling
+		if (scrollbar_v) {
+			bool visible = elem.UpperLeftCorner.Y >= clip.UpperLeftCorner.Y &&
+						   elem.LowerRightCorner.Y <= clip.LowerRightCorner.Y;
+			if (first_focus || !visible) {
+				s32 target_y = elem.UpperLeftCorner.Y;
+				if (elem.getHeight() < clip.getHeight())
+					target_y = clip.UpperLeftCorner.Y + (clip.getHeight() - elem.getHeight()) / 2;
+
+				s32 new_pos = scrollbar_v->getPos() + (s32)std::round((target_y - elem.UpperLeftCorner.Y) / scrollfactor);
+				new_pos = rangelim(new_pos, scrollbar_v->getMin(), scrollbar_v->getMax());
+
+				if (new_pos != scrollbar_v->getPos()) {
+					scrollbar_v->setPos(new_pos);
+					cont.second->updateScrolling();
+				}
+			}
+		}
+
+		// Handle horizontal scrolling
+		if (scrollbar_h) {
+			bool visible = elem.UpperLeftCorner.X >= clip.UpperLeftCorner.X &&
+						   elem.LowerRightCorner.X <= clip.LowerRightCorner.X;
+			if (first_focus || !visible) {
+				s32 target_x = elem.UpperLeftCorner.X;
+				if (elem.getWidth() < clip.getWidth())
+					target_x = clip.UpperLeftCorner.X + (clip.getWidth() - elem.getWidth()) / 2;
+
+				s32 new_pos = scrollbar_h->getPos() + (s32)std::round((target_x - elem.UpperLeftCorner.X) / scrollfactor);
+				new_pos = rangelim(new_pos, scrollbar_h->getMin(), scrollbar_h->getMax());
+
+				if (new_pos != scrollbar_h->getPos()) {
+					scrollbar_h->setPos(new_pos);
+					cont.second->updateScrolling();
+				}
+			}
+		}
+
+		break;
+	}
+}
+
 void GUIFormSpecMenu::updateSelectedItem()
 {
 	// Don't update when dragging an item
@@ -3948,6 +4055,37 @@ bool GUIFormSpecMenu::preprocessEvent(const SEvent& event)
 	if (GUIModalMenu::preprocessEvent(event))
 		return true;
 
+	// Handle keyboard and touch input to show/hide focus outline
+	switch (event.EventType) {
+	case EET_KEY_INPUT_EVENT:
+		if (event.KeyInput.PressedDown && event.KeyInput.Key == KEY_TAB &&
+				!event.KeyInput.Control) {
+			m_show_focus = true;
+			m_last_focused = nullptr;
+		}
+		break;
+	case EET_MOUSE_INPUT_EVENT:
+		switch (event.MouseInput.Event) {
+		case EMIE_LMOUSE_PRESSED_DOWN:
+		case EMIE_RMOUSE_PRESSED_DOWN:
+		case EMIE_MMOUSE_PRESSED_DOWN:
+			m_show_focus = false;
+			m_last_focused = nullptr;
+			break;
+		default:
+			break;
+		}
+		break;
+	case EET_TOUCH_INPUT_EVENT:
+		if (event.TouchInput.Event == ETIE_PRESSED_DOWN) {
+			m_show_focus = false;
+			m_last_focused = nullptr;
+		}
+		break;
+	default:
+		break;
+	}
+
 	// The IGUITabControl renders visually using the skin's selected
 	// font, which we override for the duration of form drawing,
 	// but computes tab hotspots based on how it would have rendered

src/gui/guiFormSpecMenu.h

@@ -385,6 +385,8 @@ private:
 	std::optional<std::string> m_focused_element = std::nullopt;
 	JoystickController        *m_joystick;
 	bool                       m_show_debug = false;
+	bool                       m_show_focus = false;
+	gui::IGUIElement          *m_last_focused = nullptr;
 
 	struct parserData {
 		bool explicit_size;
@@ -496,6 +498,12 @@ private:
 	void showTooltip(const std::wstring &text, const video::SColor &color,
 		const video::SColor &bgcolor);
 
+	/**
+	 * Auto-scrolls a scroll container to center the focused element.
+	 * Handles both vertical and horizontal scrolling.
+	 */
+	void autoScroll();
+
 	/**
 	 * In formspec version < 2 the elements were not ordered properly. Some element
 	 * types were drawn before others.

src/gui/guiScrollContainer.h

@@ -31,6 +31,11 @@ public:
 	void setScrollBar(GUIScrollBar *scrollbar);
 	void updateScrolling();
 
+	inline f32 getScrollFactor() const
+	{
+		return m_scrollfactor;
+	}
+
 private:
 	enum OrientationEnum
 	{

src/gui/guiTable.cpp

@@ -828,8 +828,8 @@ bool GUITable::OnEvent(const SEvent &event)
 		}
 		else if (event.KeyInput.Key == KEY_ESCAPE ||
 				event.KeyInput.Key == KEY_SPACE ||
-				(event.KeyInput.Key == KEY_TAB && event.KeyInput.Control)) {
-			// pass to parent
+				event.KeyInput.Key == KEY_TAB) {
+			// pass to parent for focus cycling (both plain Tab and Ctrl+Tab)
 			return IGUIElement::OnEvent(event);
 		}
 		else if (event.KeyInput.PressedDown && event.KeyInput.Char) {