(See SDL3/SDL_LockTexture for the SDL3 version.)

SDL_LockTexture

Lock a portion of the texture for write-only pixel access.

Header File

Syntax

int SDL_LockTexture(SDL_Texture * texture,
                    const SDL_Rect * rect,
                    void **pixels, int *pitch);

Function Parameters

SDL_Texture *	texture	the texture to lock for access, which was created with `SDL_TEXTUREACCESS_STREAMING`.
const SDL_Rect *	rect	an SDL_Rect structure representing the area to lock for access; NULL to lock the entire texture.
void **	pixels	this is filled in with a pointer to the locked pixels, appropriately offset by the locked area.
int *	pitch	this is filled in with the pitch of the locked pixels; the pitch is the length of one row in bytes.

Return Value

(int) Returns 0 on success or a negative error code if the texture is not valid or was not created with SDL_TEXTUREACCESS_STREAMING; call SDL_GetError() for more information.

Remarks

As an optimization, the pixels made available for editing don't necessarily contain the old texture data. This is a write-only operation, and if you need to keep a copy of the texture data you should do that at the application level. If the existing texture contents happen to be in the locked buffer, it is purely coincidental.

You must use SDL_UnlockTexture() to unlock the pixels and apply any changes.

Every pixel must be initialized by the caller, or uninitialized data will be uploaded to the texture during unlock.

pitch may be larger than the bytes needed for a row of pixels, as there might be padding included. Use (y * pitch) + (x * pixel_size_in_bytes) to write to the first byte of the pixel at (x, y) in the locked texture area, where (0, 0) is the top-left corner of the area.

Version

This function is available since SDL 2.0.0.