Windows build failure due to lack of `DISPLAYCONFIG_SDR_WHITE_LEVEL`

[edo9300]

I'm trying to build SDL3 with visual studio on windows, currently the library fails to build due to the absence of that struct, alongside the absence of its associated enum value DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL, on my end i have currently installed the 10.0.16299.0 sdk, and it seems those values are entirely missing from it (so it's not an issue with the wrong WINVER being defined

[sezero]

Maybe we should define that enum value as a macro for such old SDKs, like:

diff --git a/src/video/windows/SDL_windowsmodes.c b/src/video/windows/SDL_windowsmodes.c
--- a/src/video/windows/SDL_windowsmodes.c
+++ b/src/video/windows/SDL_windowsmodes.c
@@ -513,6 +513,7 @@ static float WIN_GetSDRWhitePoint(SDL_VideoDevice *_this, HMONITOR hMonitor)
     float SDR_white_level = 1.0f;

     if (WIN_GetMonitorPathInfo(videodata, hMonitor, &path_info)) {
+        #define DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL 11 /* for old SDKs. */
         DISPLAYCONFIG_SDR_WHITE_LEVEL white_level;

         SDL_zero(white_level);

@slouken?

[edo9300]

Maybe we should define that enum value as a macro for such old SDKs, like:

diff --git a/src/video/windows/SDL_windowsmodes.c b/src/video/windows/SDL_windowsmodes.c
--- a/src/video/windows/SDL_windowsmodes.c
+++ b/src/video/windows/SDL_windowsmodes.c
@@ -513,6 +513,7 @@ static float WIN_GetSDRWhitePoint(SDL_VideoDevice *_this, HMONITOR hMonitor)
     float SDR_white_level = 1.0f;

     if (WIN_GetMonitorPathInfo(videodata, hMonitor, &path_info)) {
+        #define DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL 11 /* for old SDKs. */
         DISPLAYCONFIG_SDR_WHITE_LEVEL white_level;

         SDL_zero(white_level);

@slouken?

that would solve half of the problem, to have things "cleaner" it would be better to also unconditionally redefine the struct (to another name), as it's not really easy to check if it's available or not

[slouken]

Maybe at the top of the file, we can add #ifndef DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL ...

[sezero]

Maybe at the top of the file, we can add #ifndef DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL

It's not a macro, it's an enumerated value in the DISPLAYCONFIG_DEVICE_INFO_TYPE enum, therefore it can be defined as a macro directly. (DISPLAYCONFIG_DEVICE_INFO_TYPE enum is actually present in 10.0.16299.0 sdk, but it lacks the specific value in question.)

[slouken]

@edo9300, is there any reason you can't upgrade your build SDK?

[Sackzement]

The enum value DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL is already defined in: https://github.com/libsdl-org/SDL/blob/d7be7fc168f2077accfe12a0de376082a1650b29/src/video/windows/SDL_windowsvideo.h#L241

The only thing missing is the struct DISPLAYCONFIG_SDR_WHITE_LEVEL, which is used here: https://github.com/libsdl-org/SDL/blob/d7be7fc168f2077accfe12a0de376082a1650b29/src/video/windows/SDL_windowsmodes.c#L516

Maybe it could be defined in the same header SDL_windowsvideo.h, for the SDK versions it isn't defined in?

Edit: Missed, that DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL is already inside a version check https://github.com/libsdl-org/SDL/blob/d7be7fc168f2077accfe12a0de376082a1650b29/src/video/windows/SDL_windowsvideo.h#L67

[edo9300]

@edo9300, is there any reason you can't upgrade your build SDK?

This was the sdk I happened to have installed locally, but I'm not really sure if upgrading the sdk would really be a worthwile fix for this issue, since basically half of the window support code uses checks and other means to define structs, functions and values not present in older sdks, at that point the requirement would become having a compiler with a windows 11 sdk, making all the other fallbacks meaningless

[Sackzement]

Does this help? (untested):

diff --git a/src/video/windows/SDL_windowsvideo.h b/src/video/windows/SDL_windowsvideo.h
index 87eaaaf47..24ac9de22 100644
--- a/src/video/windows/SDL_windowsvideo.h
+++ b/src/video/windows/SDL_windowsvideo.h
@@ -250,6 +250,12 @@ typedef struct DISPLAYCONFIG_DEVICE_INFO_HEADER
     UINT32 id;
 } DISPLAYCONFIG_DEVICE_INFO_HEADER;

+typedef struct DISPLAYCONFIG_SDR_WHITE_LEVEL
+{
+    DISPLAYCONFIG_DEVICE_INFO_HEADER header;
+    ULONG SDRWhiteLevel;
+} DISPLAYCONFIG_SDR_WHITE_LEVEL;
+
 typedef struct DISPLAYCONFIG_SOURCE_DEVICE_NAME
 {
     DISPLAYCONFIG_DEVICE_INFO_HEADER header;

[edo9300]

DISPLAYCONFIG_DEVICE_INFO_HEADER

that would be required for the case where WINVER is less than 0x0601, but in my case, with the windows 10 sdk, WINVER is a value greater than that, so that whole block of code won't be considered. Maybe doing checks like these would be enough https://github.com/libsdl-org/SDL/blob/1cc85c912bb3352a121b1fdc181c6ab6546157df/src/video/windows/SDL_windowsvideo.h#L329-L337 And it would be just a matter of finding what sdk added those values first, so it would become a general

#if NTDDI_VERSION < 0x0A000XXX 
#define DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL  11
typedef struct DISPLAYCONFIG_SDR_WHITE_LEVEL
{
    DISPLAYCONFIG_DEVICE_INFO_HEADER header;
    ULONG SDRWhiteLevel;
} DISPLAYCONFIG_SDR_WHITE_LEVEL;
#endif // NTDDI_VERSION < 0x0A000XXX

[edo9300]

These values seems to have been first introduced in the 10.0.17134.0 sdk, with a default NTDDI_VERSION of 0x0A000005

[slouken]

Feel free to submit a PR that works for you, and we can iterate on that in CI.