psemek/libs/sdl2/source/cursor.cpp

#include <psemek/sdl2/cursor.hpp>
#include <psemek/sdl2/init.hpp>
#include <psemek/log/log.hpp>
#include <psemek/util/enum.hpp>

#include <SDL2/SDL_mouse.h>

#include <memory>

namespace psemek::sdl2
{

	namespace
	{

		struct surface_deleter
		{
			void operator() (SDL_Surface * s) const
			{
				SDL_FreeSurface(s);
			}
		};

		struct cursor_deleter
		{
			void operator() (SDL_Cursor * c) const
			{
				SDL_FreeCursor(c);
			}
		};

		using surface_ptr = std::unique_ptr<SDL_Surface, surface_deleter>;
		using cursor_ptr = std::unique_ptr<SDL_Cursor, cursor_deleter>;

	}

	struct cursor
	{
		std::unique_ptr<SDL_Cursor, cursor_deleter> cursor;
	};

	namespace
	{

		SDL_Cursor * create_system_cursor(SDL_SystemCursor id)
		{
			auto cursor = SDL_CreateSystemCursor(id);
			if (!cursor)
				log::warning() << "Failed to create system cursor: " << SDL_GetError();
			return cursor;
		}

		struct system_cursor_provider_impl
			: cursor_provider
		{
			system_cursor_provider_impl()
			{
				arrow_.cursor.reset(create_system_cursor(SDL_SYSTEM_CURSOR_ARROW));
				beam_.cursor.reset(create_system_cursor(SDL_SYSTEM_CURSOR_IBEAM));
				hand_.cursor.reset(create_system_cursor(SDL_SYSTEM_CURSOR_HAND));
			}

			cursor const & get(cursor_type type) const override
			{
				switch (type)
				{
				case cursor_type::arrow: return arrow_;
				case cursor_type::beam: return beam_;
				case cursor_type::hand: return hand_;
				}

				throw util::unknown_enum_value_exception<cursor_type>(type);
			}

		private:
			cursor arrow_;
			cursor beam_;
			cursor hand_;
		};

		cursor_ptr create_image_cursor(image_cursor_description desc)
		{
			surface_ptr surface{SDL_CreateRGBSurfaceFrom(desc.image.data(), desc.image.width(), desc.image.height(), 32, 4 * desc.image.width(), 0x000000ffu, 0x0000ff00u, 0x00ff0000u, 0xff000000u)};
			if (!surface)
				fail("failed to create cursor surface: ");

			cursor_ptr cursor{SDL_CreateColorCursor(surface.get(), desc.pivot[0], desc.pivot[1])};
			if (!cursor)
				fail("failed to create cursor: ");

			return cursor;
		}

		struct image_cursor_provider_impl
			: cursor_provider
		{
			image_cursor_provider_impl(std::function<image_cursor_description(cursor_type)> image_provider)
			{
				arrow_.cursor = create_image_cursor(image_provider(cursor_type::arrow));
				beam_.cursor = create_image_cursor(image_provider(cursor_type::beam));
				hand_.cursor = create_image_cursor(image_provider(cursor_type::hand));
			}

			cursor const & get(cursor_type type) const override
			{
				switch (type)
				{
				case cursor_type::arrow: return arrow_;
				case cursor_type::beam: return beam_;
				case cursor_type::hand: return hand_;
				}

				throw util::unknown_enum_value_exception<cursor_type>(type);
			}

		private:
			cursor arrow_;
			cursor beam_;
			cursor hand_;
		};

	}

	std::unique_ptr<cursor_provider> system_cursor_provider()
	{
		return std::make_unique<system_cursor_provider_impl>();
	}

	std::unique_ptr<cursor_provider> image_cursor_provider(std::function<image_cursor_description(cursor_type)> image_provider)
	{
		return std::make_unique<image_cursor_provider_impl>(std::move(image_provider));
	}

	static std::unique_ptr<cursor_provider> current_provider;

	std::unique_ptr<cursor_provider> set_cursor_provider(std::unique_ptr<cursor_provider> new_provider)
	{
		std::swap(current_provider, new_provider);
		return new_provider;
	}

	cursor_provider const * get_cursor_provider()
	{
		static std::unique_ptr<cursor_provider> fallback;

		if (current_provider)
			return current_provider.get();

		if (!fallback)
			fallback = system_cursor_provider();

		return fallback.get();
	}

	void set_cursor(cursor_type type)
	{
		SDL_SetCursor(get_cursor_provider()->get(type).cursor.get());
	}


}