SDL/docs/README-migration.md

# Migrating to SDL 3.0

This guide provides useful information for migrating applications from SDL 2.0 to SDL 3.0.

We have provided a handy Python script to automate some of this work for you [link to script], and details on the changes are organized by SDL 2.0 header below.

SDL headers should now be included as `#include <SDL3/SDL.h>`. Typically that's the only header you'll need in your application unless you are using OpenGL or Vulkan functionality.

CMake users should use this snippet to include SDL support in their project:
```
find_package(SDL3 REQUIRED CONFIG REQUIRED COMPONENTS SDL3)
find_package(SDL3 REQUIRED CONFIG COMPONENTS SDL3_main)
if(TARGET SDL3::SDL3_main)
    target_link_libraries(mygame PRIVATE SDL3::SDL3_main)
endif()
target_link_libraries(mygame PRIVATE SDL3::SDL3)
```

Autotools users should use this snippet to include SDL support in their project:
```
PKG_CHECK_MODULES([SDL3], [sdl3])
```
and then add $SDL3_CFLAGS to their project CFLAGS and $SDL3_LIBS to their project LDFLAGS

Makefile users can use this snippet to include SDL support in their project:
```
CFLAGS += $(shell pkg-config sdl3 --cflags)
LDFLAGS += $(shell pkg-config sdl3 --libs)
```

The SDL3main and SDL3test libraries have been renamed SDL3_main and SDL3_test, respectively.


## SDL_events.h

The `timestamp` member of the SDL_Event structure now represents nanoseconds, and is populated with `SDL_GetTicksNS()`

The `timestamp_us` member of the sensor events has been renamed `sensor_timestamp` and now represents nanoseconds. This value is filled in from the hardware, if available, and may not be synchronized with values returned from SDL_GetTicksNS().

You should set the `event.common.timestamp` field before passing an event to `SDL_PushEvent()`. If the timestamp is 0 it will be filled in with `SDL_GetTicksNS()`.


## SDL_platform.h

The preprocessor symbol __MACOSX__ has been renamed __MACOS__, and __IPHONEOS__ has been renamed __IOS__

## SDL_pixels.h

SDL_CalculateGammaRamp has been removed, because SDL_SetWindowGammaRamp has been removed as well due to poor support in modern operating systems (see [SDL_video.h](#sdl_videoh)).


## SDL_rwops.h

SDL_RWFromFP has been removed from the API, due to issues when the SDL library uses a different C runtime from the application.

You can implement this in your own code easily:
```c
#include <stdio.h>


static Sint64 SDLCALL
stdio_size(SDL_RWops * context)
{
    Sint64 pos, size;

    pos = SDL_RWseek(context, 0, RW_SEEK_CUR);
    if (pos < 0) {
        return -1;
    }
    size = SDL_RWseek(context, 0, RW_SEEK_END);

    SDL_RWseek(context, pos, RW_SEEK_SET);
    return size;
}

static Sint64 SDLCALL
stdio_seek(SDL_RWops * context, Sint64 offset, int whence)
{
    int stdiowhence;

    switch (whence) {
    case RW_SEEK_SET:
        stdiowhence = SEEK_SET;
        break;
    case RW_SEEK_CUR:
        stdiowhence = SEEK_CUR;
        break;
    case RW_SEEK_END:
        stdiowhence = SEEK_END;
        break;
    default:
        return SDL_SetError("Unknown value for 'whence'");
    }

    if (fseek((FILE *)context->hidden.stdio.fp, (fseek_off_t)offset, stdiowhence) == 0) {
        Sint64 pos = ftell((FILE *)context->hidden.stdio.fp);
        if (pos < 0) {
            return SDL_SetError("Couldn't get stream offset");
        }
        return pos;
    }
    return SDL_Error(SDL_EFSEEK);
}

static size_t SDLCALL
stdio_read(SDL_RWops * context, void *ptr, size_t size, size_t maxnum)
{
    size_t nread;

    nread = fread(ptr, size, maxnum, (FILE *)context->hidden.stdio.fp);
    if (nread == 0 && ferror((FILE *)context->hidden.stdio.fp)) {
        SDL_Error(SDL_EFREAD);
    }
    return nread;
}

static size_t SDLCALL
stdio_write(SDL_RWops * context, const void *ptr, size_t size, size_t num)
{
    size_t nwrote;

    nwrote = fwrite(ptr, size, num, (FILE *)context->hidden.stdio.fp);
    if (nwrote == 0 && ferror((FILE *)context->hidden.stdio.fp)) {
        SDL_Error(SDL_EFWRITE);
    }
    return nwrote;
}

static int SDLCALL
stdio_close(SDL_RWops * context)
{
    int status = 0;
    if (context) {
        if (context->hidden.stdio.autoclose) {
            /* WARNING:  Check the return value here! */
            if (fclose((FILE *)context->hidden.stdio.fp) != 0) {
                status = SDL_Error(SDL_EFWRITE);
            }
        }
        SDL_FreeRW(context);
    }
    return status;
}

SDL_RWops *
SDL_RWFromFP(void *fp, SDL_bool autoclose)
{
    SDL_RWops *rwops = NULL;

    rwops = SDL_AllocRW();
    if (rwops != NULL) {
        rwops->size = stdio_size;
        rwops->seek = stdio_seek;
        rwops->read = stdio_read;
        rwops->write = stdio_write;
        rwops->close = stdio_close;
        rwops->hidden.stdio.fp = fp;
        rwops->hidden.stdio.autoclose = autoclose;
        rwops->type = SDL_RWOPS_STDFILE;
    }
    return rwops;
}
```


## SDL_stdinc.h

The standard C headers like stdio.h and stdlib.h are no longer included, you should include them directly in your project if you use non-SDL C runtime functions.
M_PI is no longer defined in SDL_stdinc.h, you can use the new symbols SDL_PI_D (double) and SDL_PI_F (float) instead.


## SDL_surface.h

Removed unused 'flags' parameter from SDL_ConvertSurface and SDL_ConvertSurfaceFormat.

SDL_CreateRGBSurface() and SDL_CreateRGBSurfaceWithFormat() have been combined into a new function SDL_CreateSurface().
SDL_CreateRGBSurfaceFrom() and SDL_CreateRGBSurfaceWithFormatFrom() have been combined into a new function SDL_CreateSurfaceFrom().

You can implement the old functions in your own code easily:
```c
SDL_Surface *SDL_CreateRGBSurface(Uint32 flags, int width, int height, int depth, Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
{
    return SDL_CreateSurface(width, height,
            SDL_MasksToPixelFormatEnum(depth, Rmask, Gmask, Bmask, Amask));
}

SDL_Surface *SDL_CreateRGBSurfaceWithFormat(Uint32 flags, int width, int height, int depth, Uint32 format)
{
    return SDL_CreateSurface(width, height, format);
}

SDL_Surface *SDL_CreateRGBSurfaceFrom(void *pixels, int width, int height, int depth, int pitch, Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
{
    return SDL_CreateSurfaceFrom(pixels, width, height, pitch,
            SDL_MasksToPixelFormatEnum(depth, Rmask, Gmask, Bmask, Amask));
}

SDL_Surface *SDL_CreateRGBSurfaceWithFormatFrom(void *pixels, int width, int height, int depth, int pitch, Uint32 format)
{
    return SDL_CreateSurfaceFrom(pixels, width, height, pitch, format);
}

```

But if you're migrating your code which uses masks, you probably have a format in mind, possibly one of these:
```c
// Various mask (R, G, B, A) and their corresponding format:
0xFF000000 0x00FF0000 0x0000FF00 0x000000FF => SDL_PIXELFORMAT_RGBA8888
0x00FF0000 0x0000FF00 0x000000FF 0xFF000000 => SDL_PIXELFORMAT_ARGB8888
0x0000FF00 0x00FF0000 0xFF000000 0x000000FF => SDL_PIXELFORMAT_BGRA8888
0x000000FF 0x0000FF00 0x00FF0000 0xFF000000 => SDL_PIXELFORMAT_ABGR8888
0x0000F800 0x000007E0 0x0000001F 0x00000000 => SDL_PIXELFORMAT_RGB565
```


## SDL_syswm.h

This header no longer includes platform specific headers and type definitions, instead allowing you to include the ones appropriate for your use case. You should define one or more of the following to enable the relevant platform-specific support:
* SDL_ENABLE_SYSWM_ANDROID
* SDL_ENABLE_SYSWM_COCOA
* SDL_ENABLE_SYSWM_KMSDRM
* SDL_ENABLE_SYSWM_UIKIT
* SDL_ENABLE_SYSWM_VIVANTE
* SDL_ENABLE_SYSWM_WAYLAND
* SDL_ENABLE_SYSWM_WINDOWS
* SDL_ENABLE_SYSWM_X11

The structures in this file are versioned separately from the rest of SDL, allowing better backwards compatibility and limited forwards compatibility with your application. Instead of calling `SDL_VERSION(&info.version)` before calling SDL_GetWindowWMInfo(), you pass the version in explicitly as `SDL_SYSWM_CURRENT_VERSION` so SDL knows what fields you expect to be filled out.

### SDL_GetWindowWMInfo

This function now returns a standard int result instead of SDL_bool, returning 0 if the function succeeds or a negative error code if there was an error. You should also pass `SDL_SYSWM_CURRENT_VERSION` as the new third version parameter. The version member of the info structure will be filled in with the version of data that is returned, the minimum of the version you requested and the version supported by the runtime SDL library.


## SDL_timer.h

SDL_GetTicks() now returns a 64-bit value. Instead of using the `SDL_TICKS_PASSED` macro, you can directly compare tick values, e.g.
```c
Uint32 deadline = SDL_GetTicks() + 1000;
...
if (SDL_TICKS_PASSED(SDL_GetTicks(), deadline)) {
    ...
}
```
becomes:
```c
Uint64 deadline = SDL_GetTicks() + 1000
...
if (SDL_GetTicks() >= deadline) {
    ...
}
```

If you were using this macro for other things besides SDL ticks values, you can define it in your own code as:
```c
#define SDL_TICKS_PASSED(A, B)  ((Sint32)((B) - (A)) <= 0)
```

## SDL_version.h

SDL_GetRevisionNumber() has been removed from the API, it always returned 0 in SDL 2.0


## SDL_video.h

SDL_SetWindowBrightness and SDL_SetWindowGammaRamp have been removed from the API, because they interact poorly with modern operating systems and aren't able to limit their effects to the SDL window.

Programs which have access to shaders can implement more robust versions of those functions using custom shader code rendered as a post-process effect.


Removed 'SDL_GL_CONTEXT_EGL' from OpenGL configuration attributes
You can instead use 'SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);'


## SDL_hints.h

The following hints have been removed:
* SDL_HINT_IDLE_TIMER_DISABLED (use SDL_DisableScreenSaver instead)
* SDL_HINT_VIDEO_X11_FORCE_EGL (use SDL_HINT_VIDEO_FORCE_EGL instead)
* SDL_HINT_VIDEO_X11_XINERAMA (Xinerama no longer supported by the X11 backend)
* SDL_HINT_VIDEO_X11_XVIDMODE (Xvidmode no longer supported by the X11 backend)