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Added SDR white point for X11 on Steam Deck

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Also disabled HDR on X11 for other devices for now, we don't know that they'll be able to display it properly.
This commit is contained in:
Sam Lantinga
2026-07-21 19:14:02 -07:00
parent 75e280618e
commit ae2301e7a5
1 changed files with 26 additions and 8 deletions
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34
src/video/x11/SDL_x11modes.c
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@@ -635,14 +635,32 @@ static bool X11_FillXRandRDisplayInfo(SDL_VideoDevice *_this, Display *dpy, int
display->internal = displaydata;
if (info) {
if (info->max_luminance > 0.0) {
/* ITU-R BT.2408-7 (Sept 2023) has the reference PQ white level at 203 nits,
* while older Dolby documentation claims a reference level of 100 nits.
*
* Use 203 nits for now.
*/
display->HDR.HDR_headroom = (float)info->max_luminance / 203.0f;
display->HDR.SDR_white_level = 1.0f;
/* ITU-R BT.2408-7 (Sept 2023) has the reference PQ white level at 203 nits,
* while older Dolby documentation claims a reference level of 100 nits.
*
* Use 203 nits for now.
*/
float SDR_white_level = 203.0f;
bool steam_deck = SDL_GetHintBoolean("SteamDeck", false);
if (steam_deck) {
// The SDR white level is dynamic, but typically is 400 nits
// We'll need some other way to get this for external displays
SDR_white_level = 400.0f;
} else {
// Support for HDR on X11 seems spotty, let's disable this for now
SDR_white_level = 0.0f;
}
// Allow a hint override for the SDR white level
const char *hint = SDL_GetHint("SDL_X11_SDR_WHITE_LEVEL");
if (hint && *hint) {
SDR_white_level = (float)SDL_atof(hint);
}
if (info->max_luminance > 0.0 && SDR_white_level > 0.0f) {
display->HDR.HDR_headroom = (float)info->max_luminance / SDR_white_level;
display->HDR.SDR_white_level = SDR_white_level / 80.0f;
}
SDL_free(info);