The new function includes the cursor position so IME UI elements can be placed relative to the cursor, as well as having the whole text area available so on-screen keyboards can avoid it.
SDL_StartTextInput(), SDL_StopTextInput(), SDL_TextInputActive(), SDL_ClearComposition(), and SDL_SetTextInputRect() all now take a window parameter.
This change also fixes IME candidate positioning when SDL_SetTextInputRect() is called before SDL_StartTextInput(), as is recommended in the documentation.
This means the allocator's caller doesn't need to use SDL_OutOfMemory directly
if the allocation fails.
This applies to the usual allocators: SDL_malloc, SDL_calloc, SDL_realloc
(all of these regardless of if the app supplied a custom allocator or we're
using system malloc() or an internal copy of dlmalloc under the hood),
SDL_aligned_alloc, SDL_small_alloc, SDL_strdup, SDL_asprintf, SDL_wcsdup...
probably others. If it returns something you can pass to SDL_free, it should
work.
The caller might still need to use SDL_OutOfMemory if something that wasn't
SDL allocated the memory: operator new in C++ code, Objective-C's alloc
message, win32 GlobalAlloc, etc.
Fixes#8642.