Bug 1812676 - Improve font-style:oblique mapping to 'slnt' variation. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D167989

gfx/thebes/gfxFont.cpp

@@ -818,7 +818,7 @@ float gfxFont::AngleForSyntheticOblique() const {
   // If the style doesn't call for italic/oblique, or if the face already
   // provides it, no synthetic style should be added.
   if (mStyle.style == FontSlantStyle::NORMAL || !mStyle.allowSyntheticStyle ||
-      !mFontEntry->IsUpright()) {
+      !mFontEntry->IsUpright() || mFontEntry->HasSlantVariation()) {
     return 0.0f;
   }
 

gfx/thebes/gfxFontEntry.cpp

@@ -1267,6 +1267,8 @@ void gfxFontEntry::CheckForVariationAxes() {
       } else if (axis.mTag == HB_TAG('i', 't', 'a', 'l') &&
                  axis.mMaxValue >= 1.0f) {
         mRangeFlags |= RangeFlags::eItalicVariation;
+      } else if (axis.mTag == HB_TAG('s', 'l', 'n', 't')) {
+        mRangeFlags |= RangeFlags::eSlantVariation;
       } else if (axis.mTag == HB_TAG('o', 'p', 's', 'z')) {
         mRangeFlags |= RangeFlags::eOpticalSize;
       }
@@ -1288,6 +1290,13 @@ bool gfxFontEntry::HasItalicVariation() {
   return bool(mRangeFlags & RangeFlags::eItalicVariation);
 }
 
+bool gfxFontEntry::HasSlantVariation() {
+  MOZ_ASSERT(!mIsUserFontContainer,
+             "should not be called for user-font containers!");
+  CheckForVariationAxes();
+  return bool(mRangeFlags & RangeFlags::eSlantVariation);
+}
+
 bool gfxFontEntry::HasOpticalSize() {
   MOZ_ASSERT(!mIsUserFontContainer,
              "should not be called for user-font containers!");
@@ -1336,7 +1345,7 @@ void gfxFontEntry::GetVariationsForStyle(nsTArray<gfxFontVariation>& aResult,
     // The 'ital' axis is normally a binary toggle; intermediate values
     // can only be set using font-variation-settings.
     aResult.AppendElement(gfxFontVariation{HB_TAG('i', 't', 'a', 'l'), 1.0f});
-  } else if (SlantStyle().Min().IsOblique()) {
+  } else if (HasSlantVariation()) {
     // Figure out what slant angle we should try to match from the
     // requested style.
     float angle = aStyle.style.IsNormal() ? 0.0f

gfx/thebes/gfxFontEntry.h

@@ -452,6 +452,7 @@ class gfxFontEntry {
 
   bool HasBoldVariableWeight();
   bool HasItalicVariation();
+  bool HasSlantVariation();
   bool HasOpticalSize();
 
   void CheckForVariationAxes();
@@ -552,7 +553,7 @@ class gfxFontEntry {
   // descriptors, it is treated as the initial value for font-matching (and
   // so that is what we record in the font entry), but when rendering the
   // range is NOT clamped.
-  enum class RangeFlags : uint8_t {
+  enum class RangeFlags : uint16_t {
     eNoFlags = 0,
     eAutoWeight = (1 << 0),
     eAutoStretch = (1 << 1),
@@ -564,16 +565,18 @@ class gfxFontEntry {
     eBoldVariableWeight = (1 << 3),
     // Whether the face has an 'ital' axis.
     eItalicVariation = (1 << 4),
+    // Whether the face has a 'slnt' axis.
+    eSlantVariation = (1 << 5),
 
     // Flags to record if the face uses a non-CSS-compatible scale
     // for weight and/or stretch, in which case we won't map the
     // properties to the variation axes (though they can still be
     // explicitly set using font-variation-settings).
-    eNonCSSWeight = (1 << 5),
-    eNonCSSStretch = (1 << 6),
+    eNonCSSWeight = (1 << 6),
+    eNonCSSStretch = (1 << 7),
 
     // Whether the font has an 'opsz' axis.
-    eOpticalSize = (1 << 7)
+    eOpticalSize = (1 << 8)
   };
   RangeFlags mRangeFlags = RangeFlags::eNoFlags;
 

testing/web-platform/meta/css/css-fonts/font-face-style-auto-variable.html.ini

@@ -1,2 +0,0 @@
-[font-face-style-auto-variable.html]
-  expected: FAIL

testing/web-platform/meta/css/css-fonts/font-face-style-default-variable.html.ini

@@ -1,2 +0,0 @@
-[font-face-style-default-variable.html]
-  expected: FAIL