Bug 1798067 Part 1: Add SupportsHDR to gfxPlatform, refactor macOS to use it. r=gfx-reviewers,lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D161364

gfx/thebes/gfxPlatform.h

@@ -805,6 +805,8 @@ class gfxPlatform : public mozilla::layers::MemoryPressureListener {
 
   static bool UseDesktopZoomingScrollbars();
 
+  virtual bool SupportsHDR() { return false; }
+
  protected:
   gfxPlatform();
   virtual ~gfxPlatform();

gfx/thebes/gfxPlatformMac.cpp

@@ -996,6 +996,24 @@ gfxPlatformMac::CreateGlobalHardwareVsyncSource() {
   return osxVsyncSource.forget();
 }
 
+bool gfxPlatformMac::SupportsHDR() {
+  // HDR has 3 requirements:
+  // 1) high peak brightness
+  // 2) high contrast ratio
+  // 3) color depth > 24
+  if (GetScreenDepth() <= 24) {
+    return false;
+  }
+  // Screen is capable. Is the OS capable?
+#ifdef EARLY_BETA_OR_EARLIER
+  // More-or-less supported in Catalina.
+  return nsCocoaFeatures::OnCatalinaOrLater();
+#else
+  // Definitely supported in Big Sur.
+  return nsCocoaFeatures::OnBigSurOrLater();
+#endif
+}
+
 nsTArray<uint8_t> gfxPlatformMac::GetPlatformCMSOutputProfileData() {
   nsTArray<uint8_t> prefProfileData = GetPrefCMSOutputProfileData();
   if (!prefProfileData.IsEmpty()) {

gfx/thebes/gfxPlatformMac.h

@@ -76,6 +76,8 @@ class gfxPlatformMac : public gfxPlatform {
 
   static bool CheckVariationFontSupport();
 
+  bool SupportsHDR() override;
+
  protected:
   bool AccelerateLayersByDefault() override;
 

widget/cocoa/nsLookAndFeel.mm

@@ -484,13 +484,13 @@ nsresult nsLookAndFeel::NativeGetInt(IntID aID, int32_t& aResult) {
     case IntID::UseAccessibilityTheme:
       aResult = NSWorkspace.sharedWorkspace.accessibilityDisplayShouldIncreaseContrast;
       break;
-    case IntID::VideoDynamicRange:
-#ifdef EARLY_BETA_OR_EARLIER
-      aResult = nsCocoaFeatures::OnCatalinaOrLater();
-#else
-      aResult = nsCocoaFeatures::OnBigSurOrLater();
-#endif
+    case IntID::VideoDynamicRange: {
+      // If the platform says it supports HDR, then we claim to support video-dynamic-range.
+      gfxPlatform* platform = gfxPlatform::GetPlatform();
+      MOZ_ASSERT(platform);
+      aResult = platform->SupportsHDR();
       break;
+    }
     case IntID::PanelAnimations:
       aResult = 1;
       break;
@@ -687,8 +687,8 @@ void nsLookAndFeel::RecordAccessibilityTelemetry() {
 }
 
 - (void)cachedValuesChanged {
-  // We only need to re-cache (and broadcast) updated LookAndFeel values, so that they're up-to-date
-  // the next time they're queried. No further change handling is needed.
+  // We only need to re-cache (and broadcast) updated LookAndFeel values, so that they're
+  // up-to-date the next time they're queried. No further change handling is needed.
   // TODO: Add a change hint for this which avoids the unnecessary media query invalidation.
   LookAndFeel::NotifyChangedAllWindows(widget::ThemeChangeKind::MediaQueriesOnly);
 }