Keeping run metrics rather than calculating them every time

Change-Id: Ic0257859317cf46dbb90277573f184d565fdb58d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/295322
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Julia Lavrova <jlavrova@google.com>

modules/skparagraph/src/ParagraphImpl.cpp

@@ -540,7 +540,7 @@ void ParagraphImpl::buildClusterTable() {
         run.setClusterRange(runStart, fClusters.size());
         fMaxIntrinsicWidth += run.advance().fX;
     }
-  fClustersIndexFromCodeUnit[fText.size()] = fClusters.size();
+    fClustersIndexFromCodeUnit[fText.size()] = fClusters.size();
     fClusters.emplace_back(this, EMPTY_RUN, 0, 0, this->text({fText.size(), fText.size()}), 0, 0);
 }
 

modules/skparagraph/src/Run.cpp

@@ -17,7 +17,7 @@ namespace textlayout {
 Run::Run(ParagraphImpl* master,
          const SkShaper::RunHandler::RunInfo& info,
          size_t firstChar,
-         SkScalar lineHeight,
+         SkScalar heightMultiplier,
          size_t index,
          SkScalar offsetX)
     : fMaster(master)
@@ -25,7 +25,7 @@ Run::Run(ParagraphImpl* master,
     , fClusterRange(EMPTY_CLUSTERS)
     , fFont(info.fFont)
     , fClusterStart(firstChar)
-    , fHeightMultiplier(lineHeight)
+    , fHeightMultiplier(heightMultiplier)
 {
     fBidiLevel = info.fBidiLevel;
     fAdvance = info.fAdvance;
@@ -38,6 +38,9 @@ Run::Run(ParagraphImpl* master,
     fClusterIndexes.push_back_n(info.glyphCount + 1);
     fShifts.push_back_n(info.glyphCount + 1, 0.0);
     info.fFont.getMetrics(&fFontMetrics);
+
+    this->calculateMetrics();
+
     fSpaced = false;
     // To make edge cases easier:
     fPositions[info.glyphCount] = fOffset + fAdvance;
@@ -46,6 +49,18 @@ Run::Run(ParagraphImpl* master,
     fPlaceholderIndex = std::numeric_limits<size_t>::max();
 }
 
+void Run::calculateMetrics() {
+    fCorrectAscent = fFontMetrics.fAscent - fFontMetrics.fLeading * 0.5;
+    fCorrectDescent = fFontMetrics.fDescent + fFontMetrics.fLeading * 0.5;
+    fCorrectLeading = 0;
+    if (!SkScalarNearlyZero(fHeightMultiplier)) {
+        auto multiplier = fHeightMultiplier * fFont.getSize() /
+                             (fFontMetrics.fDescent - fFontMetrics.fAscent + fFontMetrics.fLeading);
+        fCorrectAscent *= multiplier;
+        fCorrectDescent *= multiplier;
+    }
+}
+
 SkShaper::RunHandler::Buffer Run::newRunBuffer() {
     return {fGlyphs.data(), fPositions.data(), nullptr, fClusterIndexes.data(), fOffset};
 }
@@ -267,6 +282,8 @@ void Run::updateMetrics(InternalLineMetrics* endlineMetrics) {
             break;
     }
 
+    this->calculateMetrics();
+
     // Make sure the placeholder can fit the line
     endlineMetrics->add(this);
 }

modules/skparagraph/src/Run.h

@@ -60,7 +60,7 @@ public:
     Run(ParagraphImpl* master,
         const SkShaper::RunHandler::RunInfo& info,
         size_t firstChar,
-        SkScalar lineHeight,
+        SkScalar heightMultiplier,
         size_t index,
         SkScalar shiftX);
     Run(const Run&) = default;
@@ -84,36 +84,15 @@ public:
         fOffset.fY += shiftY;
     }
     SkVector advance() const {
-        return SkVector::Make(fAdvance.fX, fFontMetrics.fDescent - fFontMetrics.fAscent);
+        return SkVector::Make(fAdvance.fX, fFontMetrics.fDescent - fFontMetrics.fAscent + fFontMetrics.fLeading);
     }
     SkVector offset() const { return fOffset; }
     SkScalar ascent() const { return fFontMetrics.fAscent; }
     SkScalar descent() const { return fFontMetrics.fDescent; }
     SkScalar leading() const { return fFontMetrics.fLeading; }
-    SkScalar correctAscent() const {
-
-        if (fHeightMultiplier == 0) {
-            return fFontMetrics.fAscent - fFontMetrics.fLeading / 2;
-        }
-        return fFontMetrics.fAscent * fHeightMultiplier * fFont.getSize() /
-                (fFontMetrics.fDescent - fFontMetrics.fAscent + fFontMetrics.fLeading / 2);
-    }
-    SkScalar correctDescent() const {
-
-        if (fHeightMultiplier == 0) {
-            return fFontMetrics.fDescent + fFontMetrics.fLeading / 2;
-        }
-        return fFontMetrics.fDescent * fHeightMultiplier * fFont.getSize() /
-                (fFontMetrics.fDescent - fFontMetrics.fAscent + fFontMetrics.fLeading / 2);
-    }
-    SkScalar correctLeading() const {
-
-        if (fHeightMultiplier == 0) {
-            return fFontMetrics.fAscent;
-        }
-        return fFontMetrics.fLeading * fHeightMultiplier * fFont.getSize() /
-                (fFontMetrics.fDescent - fFontMetrics.fAscent + fFontMetrics.fLeading);
-    }
+    SkScalar correctAscent() const { return fCorrectAscent; }
+    SkScalar correctDescent() const { return fCorrectDescent; }
+    SkScalar correctLeading() const { return fCorrectLeading; }
     const SkFont& font() const { return fFont; }
     bool leftToRight() const { return fBidiLevel % 2 == 0; }
     TextDirection getTextDirection() const { return leftToRight() ? TextDirection::kLtr : TextDirection::kRtl; }
@@ -132,6 +111,7 @@ public:
 
     bool isEllipsis() const { return fEllipsis; }
 
+    void calculateMetrics();
     void updateMetrics(InternalLineMetrics* endlineMetrics);
 
     void setClusterRange(size_t from, size_t to) { fClusterRange = ClusterRange(from, to); }
@@ -217,6 +197,9 @@ private:
 
     SkFontMetrics fFontMetrics;
     const SkScalar fHeightMultiplier;
+    SkScalar fCorrectAscent;
+    SkScalar fCorrectDescent;
+    SkScalar fCorrectLeading;
 
     bool fSpaced;
     bool fEllipsis;

modules/skparagraph/src/TextWrapper.h

@@ -75,6 +75,7 @@ class TextWrapper {
                 fStart = ClusterPos(cluster, cluster->startPos());
             }
             fEnd = ClusterPos(cluster, cluster->endPos());
+            // TODO: Make sure all the checks are correct and there are no unnecessary checks
             if (!cluster->run()->isPlaceholder()) {
                 fMetrics.add(cluster->run());
             }