# SDL_MUSTLOCK

Evaluates to true if the surface needs to be locked before access.

## Header File

Defined in [<SDL3/SDL_surface.h>](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_surface.h)

## Syntax

```c
#define SDL_MUSTLOCK(S) (((S)->flags & SDL_SURFACE_LOCK_NEEDED) == SDL_SURFACE_LOCK_NEEDED)
```

## Version

This macro is available since SDL 3.2.0.

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[CategoryAPI](CategoryAPI), [CategoryAPIMacro](CategoryAPIMacro), [CategorySurface](CategorySurface)

