camera: add PipeWire camera support

The PipeWire camera will enumerate the pipewire Video/Source nodes with
their formats.

When capturing is started, a stream to the node will be created and
frames will be captured.

cmake/sdlchecks.cmake

@@ -139,13 +139,16 @@ macro(CheckPipewire)
     if(PC_PIPEWIRE_FOUND)
       set(HAVE_PIPEWIRE TRUE)
       sdl_glob_sources("${SDL3_SOURCE_DIR}/src/audio/pipewire/*.c")
+      sdl_glob_sources("${SDL3_SOURCE_DIR}/src/camera/pipewire/*.c")
       set(SDL_AUDIO_DRIVER_PIPEWIRE 1)
+      set(SDL_CAMERA_DRIVER_PIPEWIRE 1)
       if(SDL_PIPEWIRE_SHARED AND NOT HAVE_SDL_LOADSO)
         message(WARNING "You must have SDL_LoadObject() support for dynamic PipeWire loading")
       endif()
       FindLibraryAndSONAME("pipewire-0.3" LIBDIRS ${PC_PIPEWIRE_LIBRARY_DIRS})
       if(SDL_PIPEWIRE_SHARED AND PIPEWIRE_0.3_LIB AND HAVE_SDL_LOADSO)
         set(SDL_AUDIO_DRIVER_PIPEWIRE_DYNAMIC "\"${PIPEWIRE_0.3_LIB_SONAME}\"")
+        set(SDL_CAMERA_DRIVER_PIPEWIRE_DYNAMIC "\"${PIPEWIRE_0.3_LIB_SONAME}\"")
         set(HAVE_PIPEWIRE_SHARED TRUE)
         sdl_link_dependency(pipewire INCLUDES $<TARGET_PROPERTY:PkgConfig::PC_PIPEWIRE,INTERFACE_INCLUDE_DIRECTORIES>)
       else()

include/build_config/SDL_build_config.h.cmake

@@ -485,6 +485,8 @@
 #cmakedefine SDL_CAMERA_DRIVER_ANDROID @SDL_CAMERA_DRIVER_ANDROID@
 #cmakedefine SDL_CAMERA_DRIVER_EMSCRIPTEN @SDL_CAMERA_DRIVER_EMSCRIPTEN@
 #cmakedefine SDL_CAMERA_DRIVER_MEDIAFOUNDATION @SDL_CAMERA_DRIVER_MEDIAFOUNDATION@
+#cmakedefine SDL_CAMERA_DRIVER_PIPEWIRE @SDL_CAMERA_DRIVER_PIPEWIRE@
+#cmakedefine SDL_CAMERA_DRIVER_PIPEWIRE_DYNAMIC @SDL_CAMERA_DRIVER_PIPEWIRE_DYNAMIC@
 
 /* Enable misc subsystem */
 #cmakedefine SDL_MISC_DUMMY @SDL_MISC_DUMMY@

src/camera/SDL_camera.c

@@ -34,6 +34,9 @@ static const CameraBootStrap *const bootstrap[] = {
 #ifdef SDL_CAMERA_DRIVER_V4L2
     &V4L2_bootstrap,
 #endif
+#ifdef SDL_CAMERA_DRIVER_PIPEWIRE
+    &PIPEWIRECAMERA_bootstrap,
+#endif
 #ifdef SDL_CAMERA_DRIVER_COREMEDIA
     &COREMEDIA_bootstrap,
 #endif

src/camera/SDL_syscamera.h

@@ -205,6 +205,7 @@ typedef struct CameraBootStrap
 // Not all of these are available in a given build. Use #ifdefs, etc.
 extern CameraBootStrap DUMMYCAMERA_bootstrap;
 extern CameraBootStrap V4L2_bootstrap;
+extern CameraBootStrap PIPEWIRECAMERA_bootstrap;
 extern CameraBootStrap COREMEDIA_bootstrap;
 extern CameraBootStrap ANDROIDCAMERA_bootstrap;
 extern CameraBootStrap EMSCRIPTENCAMERA_bootstrap;