Work on fetch sdl: only one fetch implementation

CMakeLists.txt

@@ -255,19 +255,6 @@ if (HELLOIMGUI_WITH_GLFW
     endif()
 endif()
 
-# Shall we fetch sdl? (fill shall_fetch_sdl)
-set(shall_fetch_sdl OFF)
-if (HELLOIMGUI_WITH_SDL
-    AND NOT HELLOIMGUI_USE_SDL_SYSTEM_LIB
-    AND NOT TARGET sdl
-    AND NOT EMSCRIPTEN
-    )
-    find_package(SDL2 QUIET)
-    if (NOT SDL2_FOUND)
-        set(shall_fetch_sdl ON)
-    endif()
-endif()
-
 
 #------------------------------------------------------------------------------
 # Download backend glfw or sdl if required
@@ -284,18 +271,6 @@ if (shall_fetch_glfw)
     set(need_fetch_make_available_glfw ON)
 endif()
 
-if (shall_fetch_sdl)
-    message(STATUS "HelloImGui: downloading and building SDL")
-    include(FetchContent)
-    Set(FETCHCONTENT_QUIET FALSE)
-    FetchContent_Declare(sdl
-        GIT_REPOSITORY    https://github.com/libsdl-org/SDL.git
-        GIT_TAG           release-2.24.2
-        GIT_PROGRESS TRUE
-        )
-    set(need_fetch_make_available_sdl ON)
-endif()
-
 if (NOT (HELLOIMGUI_USE_SDL_OPENGL3 OR HELLOIMGUI_USE_GLFW_OPENGL3 OR HELLOIMGUI_CREATE_ANDROID_STUDIO_PROJECT))
     message(FATAL_ERROR "Select at least one backend: use either
         -DHELLOIMGUI_USE_SDL_OPENGL3=ON

src/hello_imgui/CMakeLists.txt

@@ -192,13 +192,31 @@ endfunction()
 
 
 function(_him_fetch_sdl_if_needed)
+    set(shall_fetch_sdl OFF)
+
+    # Always fetch SDL for iOS and Android
     if (HELLOIMGUI_USE_SDL_OPENGL3 AND (IOS OR ANDROID))
+        set(shall_fetch_sdl ON)
+    endif()
+
+    # Fetch SDL if:
+    # option HELLOIMGUI_WITH_SDL was passed
+    # and SDL not available by find_package
+    # and HELLOIMGUI_USE_SDL_SYSTEM_LIB is OFF
+    if (HELLOIMGUI_WITH_SDL AND NOT HELLOIMGUI_USE_SDL_SYSTEM_LIB
+        AND NOT TARGET sdl AND NOT EMSCRIPTEN)
+        find_package(SDL2 QUIET)
+        if (NOT SDL2_FOUND)
+            set(shall_fetch_sdl ON)
+        endif()
+    endif()
+
+    if (shall_fetch_sdl)
         _him_fetch_declare_sdl()
         if(ANDROID)
             FetchContent_Populate(sdl)
             _him_prepare_android_sdl_symlink()
-        endif()
-        if(IOS)
+        else()
             FetchContent_MakeAvailable(sdl)
         endif()
     endif()