Implement an editor to customize the touchscreen controls (#14933)

- The editor is accessible via the pause menu and the settings menu.
- Buttons can be moved via drag & drop.
- Buttons can be added/removed. The grid menu added by #14918 is used to show
  all buttons not included in the layout.
- Custom layouts are responsive and adapt to changed screen size / DPI /
  hud_scaling.
- The layout is saved as JSON in the "touch_layout" setting.

src/gui/touchcontrols.h

@@ -5,11 +5,8 @@
 
 #pragma once
 
-#include "IGUIStaticText.h"
 #include "irrlichttypes.h"
-#include <IEventReceiver.h>
-#include <IGUIImage.h>
-#include <IGUIEnvironment.h>
+#include "IEventReceiver.h"
 
 #include <memory>
 #include <optional>
@@ -17,41 +14,29 @@
 #include <vector>
 
 #include "itemdef.h"
-#include "client/game.h"
+#include "touchscreenlayout.h"
 #include "util/basic_macros.h"
-#include "client/texturesource.h"
 
 namespace irr
 {
 	class IrrlichtDevice;
+	namespace gui
+	{
+		class IGUIEnvironment;
+		class IGUIImage;
+		class IGUIStaticText;
+	}
+	namespace video
+	{
+		class IVideoDriver;
+	}
 }
+class ISimpleTextureSource;
 
 using namespace irr::core;
 using namespace irr::gui;
 
 
-// We cannot use irr_ptr for Irrlicht GUI elements we own.
-// Option 1: Pass IGUIElement* returned by IGUIEnvironment::add* into irr_ptr
-//           constructor.
-//           -> We steal the reference owned by IGUIEnvironment and drop it later,
-//           causing the IGUIElement to be deleted while IGUIEnvironment still
-//           references it.
-// Option 2: Pass IGUIElement* returned by IGUIEnvironment::add* into irr_ptr::grab.
-//           -> We add another reference and drop it later, but since IGUIEnvironment
-//           still references the IGUIElement, it is never deleted.
-// To make IGUIEnvironment drop its reference to the IGUIElement, we have to call
-// IGUIElement::remove, so that's what we'll do.
-template <typename T>
-std::shared_ptr<T> grab_gui_element(T *element)
-{
-	static_assert(std::is_base_of_v<IGUIElement, T>,
-			"grab_gui_element only works for IGUIElement");
-	return std::shared_ptr<T>(element, [](T *e) {
-		e->remove();
-	});
-}
-
-
 enum class TapState
 {
 	None,
@@ -59,36 +44,6 @@ enum class TapState
 	LongTap,
 };
 
-enum touch_gui_button_id
-{
-	jump_id = 0,
-	sneak_id,
-	zoom_id,
-	aux1_id,
-	overflow_id,
-
-	// usually in the "settings bar"
-	fly_id,
-	noclip_id,
-	fast_id,
-	debug_id,
-	camera_id,
-	range_id,
-	minimap_id,
-	toggle_chat_id,
-
-	// usually in the "rare controls bar"
-	chat_id,
-	inventory_id,
-	drop_id,
-	exit_id,
-
-	// the joystick
-	joystick_off_id,
-	joystick_bg_id,
-	joystick_center_id,
-};
-
 
 #define BUTTON_REPEAT_DELAY 0.5f
 #define BUTTON_REPEAT_INTERVAL 0.333f
@@ -168,6 +123,9 @@ public:
 	bool isStatusTextOverriden() { return m_overflow_open; }
 	IGUIStaticText *getStatusText() { return m_status_text.get(); }
 
+	ButtonLayout getLayout() { return m_layout; }
+	void applyLayout(const ButtonLayout &layout);
+
 private:
 	IrrlichtDevice *m_device = nullptr;
 	IGUIEnvironment *m_guienv = nullptr;
@@ -233,13 +191,14 @@ private:
 	void releaseAll();
 
 	// initialize a button
+	bool mayAddButton(touch_gui_button_id id);
 	void addButton(std::vector<button_info> &buttons,
 			touch_gui_button_id id, const std::string &image,
-			const recti &rect, bool visible=true);
+			const recti &rect, bool visible);
 	void addToggleButton(std::vector<button_info> &buttons,
 			touch_gui_button_id id,
 			const std::string &image_1, const std::string &image_2,
-			const recti &rect, bool visible=true);
+			const recti &rect, bool visible);
 
 	IGUIImage *makeButtonDirect(touch_gui_button_id id,
 			const recti &rect, bool visible);
@@ -268,6 +227,8 @@ private:
 
 	bool m_place_pressed = false;
 	u64 m_place_pressed_until = 0;
+
+	ButtonLayout m_layout;
 };
 
 extern TouchControls *g_touchcontrols;