Add oblique as a slant.

Some fonts have italic and oblique in the same family, see

http://lucidafonts.com/fonts/family/lucida-sans
http://www.gust.org.pl/projects/e-foundry/latin-modern

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1921903002

Chromium side change at https://crrev.com/1921503006/ .

Review-Url: https://codereview.chromium.org/1921903002

1 files changed, 39 insertions, 24 deletions

diff --git a/src/core/SkFontMgr.cpp b/src/core/SkFontMgr.cpp
index eba2b28fd6..ebb9a89662 100644
--- a/src/core/SkFontMgr.cpp
+++ b/src/core/SkFontMgr.cpp
@@ -211,6 +211,9 @@ SkTypeface* SkFontStyleSet::matchStyleCSS3(const SkFontStyle& pattern) {
     struct Score {
         int score;
         int index;
+        Score& operator +=(int rhs) { this->score += rhs; return *this; }
+        Score& operator <<=(int rhs) { this->score <<= rhs; return *this; }
+        bool operator <(const Score& that) { return this->score < that.score; }
     };
 
     Score maxScore = { 0, 0 };
@@ -219,58 +222,70 @@ SkTypeface* SkFontStyleSet::matchStyleCSS3(const SkFontStyle& pattern) {
         this->getStyle(i, &current, nullptr);
         Score currentScore = { 0, i };
 
-        // CSS stretch. (This is the width.)
-        // This has the highest priority.
+        // CSS stretch / SkFontStyle::Width
+        // Takes priority over everything else.
         if (pattern.width() <= SkFontStyle::kNormal_Width) {
             if (current.width() <= pattern.width()) {
-                currentScore.score += 10 - pattern.width() + current.width();
+                currentScore += 10 - pattern.width() + current.width();
             } else {
-                currentScore.score += 10 - current.width();
+                currentScore += 10 - current.width();
             }
         } else {
             if (current.width() > pattern.width()) {
-                currentScore.score += 10 + pattern.width() - current.width();
+                currentScore += 10 + pattern.width() - current.width();
             } else {
-                currentScore.score += current.width();
+                currentScore += current.width();
             }
         }
-        currentScore.score *= 1002;
-
-        // CSS style (italic/oblique)
-        // Being italic trumps all valid weights which are not italic.
-        // Note that newer specs differentiate between italic and oblique.
-        if (pattern.isItalic() == current.isItalic()) {
-            currentScore.score += 1001;
-        }
-
-        // Synthetics (weight/style) [no stretch synthetic?]
-
+        currentScore <<= 8;
+
+        // CSS style (normal, italic, oblique) / SkFontStyle::Slant (upright, italic, oblique)
+        // Takes priority over all valid weights.
+        static_assert(SkFontStyle::kUpright_Slant == 0 &&
+                      SkFontStyle::kItalic_Slant  == 1 &&
+                      SkFontStyle::kOblique_Slant == 2,
+                      "SkFontStyle::Slant values not as required.");
+        SkASSERT(0 <= pattern.slant() && pattern.slant() <= 2 &&
+                 0 <= current.slant() && current.slant() <= 2);
+        static const int score[3][3] = {
+            /*               Upright Italic Oblique  [current]*/
+            /*   Upright */ {   3   ,  1   ,   2   },
+            /*   Italic  */ {   1   ,  3   ,   2   },
+            /*   Oblique */ {   1   ,  2   ,   3   },
+            /* [pattern] */
+        };
+        currentScore += score[pattern.slant()][current.slant()];
+        currentScore <<= 8;
+
+        // Synthetics (weight, style) [no stretch synthetic?]
+
+        // CSS weight / SkFontStyle::Weight
         // The 'closer' to the target weight, the higher the score.
         // 1000 is the 'heaviest' recognized weight
         if (pattern.weight() == current.weight()) {
-            currentScore.score += 1000;
+            currentScore += 1000;
         } else if (pattern.weight() <= 500) {
             if (400 <= pattern.weight() && pattern.weight() < 450) {
                 if (450 <= current.weight() && current.weight() <= 500) {
                     // Artificially boost the 500 weight.
                     // TODO: determine correct number to use.
-                    currentScore.score += 500;
+                    currentScore += 500;
                 }
             }
             if (current.weight() <= pattern.weight()) {
-                currentScore.score += 1000 - pattern.weight() + current.weight();
+                currentScore += 1000 - pattern.weight() + current.weight();
             } else {
-                currentScore.score += 1000 - current.weight();
+                currentScore += 1000 - current.weight();
             }
         } else if (pattern.weight() > 500) {
             if (current.weight() > pattern.weight()) {
-                currentScore.score += 1000 + pattern.weight() - current.weight();
+                currentScore += 1000 + pattern.weight() - current.weight();
             } else {
-                currentScore.score += current.weight();
+                currentScore += current.weight();
             }
         }
 
-        if (currentScore.score > maxScore.score) {
+        if (maxScore < currentScore) {
             maxScore = currentScore;
         }
     }