From 88e48f24546fe075d356816bae34a90381cd4296 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 22 May 2022 20:24:57 +0300
Subject: [PATCH] Support image-based cursors

---
 libs/sdl2/CMakeLists.txt                 |  2 +-
 libs/sdl2/include/psemek/sdl2/cursor.hpp | 11 +++++
 libs/sdl2/source/cursor.cpp              | 56 ++++++++++++++++++++++++
 3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/libs/sdl2/CMakeLists.txt b/libs/sdl2/CMakeLists.txt
index 1db2f5aa..53e0c832 100644
--- a/libs/sdl2/CMakeLists.txt
+++ b/libs/sdl2/CMakeLists.txt
@@ -5,4 +5,4 @@ file(GLOB_RECURSE PSEMEK_SDL2_SOURCES RELATIVE "${CMAKE_CURRENT_SOURCE_DIR}" "so
 
 psemek_add_library(psemek-sdl2 ${PSEMEK_SDL2_HEADERS} ${PSEMEK_SDL2_SOURCES})
 target_include_directories(psemek-sdl2 PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/include")
-target_link_libraries(psemek-sdl2 PUBLIC psemek-log psemek-util SDL2)
+target_link_libraries(psemek-sdl2 PUBLIC psemek-log psemek-util psemek-gfx SDL2)
diff --git a/libs/sdl2/include/psemek/sdl2/cursor.hpp b/libs/sdl2/include/psemek/sdl2/cursor.hpp
index 13e50c75..48ee8e15 100644
--- a/libs/sdl2/include/psemek/sdl2/cursor.hpp
+++ b/libs/sdl2/include/psemek/sdl2/cursor.hpp
@@ -1,6 +1,10 @@
 #pragma once
 
+#include <psemek/gfx/pixmap.hpp>
+#include <psemek/geom/point.hpp>
+
 #include <memory>
+#include <functional>
 
 namespace psemek::sdl2
 {
@@ -21,7 +25,14 @@ namespace psemek::sdl2
 		virtual ~cursor_provider() {}
 	};
 
+	struct image_cursor_description
+	{
+		gfx::pixmap_rgba image;
+		geom::point<int, 2> pivot;
+	};
+
 	std::unique_ptr<cursor_provider> system_cursor_provider();
+	std::unique_ptr<cursor_provider> image_cursor_provider(std::function<image_cursor_description(cursor_type)> image_provider);
 
 	std::unique_ptr<cursor_provider> set_cursor_provider(std::unique_ptr<cursor_provider> new_provider);
 	cursor_provider const * get_cursor_provider();
diff --git a/libs/sdl2/source/cursor.cpp b/libs/sdl2/source/cursor.cpp
index 2e4e16ca..20457695 100644
--- a/libs/sdl2/source/cursor.cpp
+++ b/libs/sdl2/source/cursor.cpp
@@ -1,4 +1,5 @@
 #include <psemek/sdl2/cursor.hpp>
+#include <psemek/sdl2/init.hpp>
 #include <psemek/log/log.hpp>
 #include <psemek/util/enum.hpp>
 
@@ -12,6 +13,14 @@ 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
@@ -20,6 +29,7 @@ namespace psemek::sdl2
 			}
 		};
 
+		using surface_ptr = std::unique_ptr<SDL_Surface, surface_deleter>;
 		using cursor_ptr = std::unique_ptr<SDL_Cursor, cursor_deleter>;
 
 	}
@@ -68,6 +78,47 @@ namespace psemek::sdl2
 			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()
@@ -75,6 +126,11 @@ namespace psemek::sdl2
 		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)