Adjust visual overflow rect for rounded/shifted ascent/descent

third_party/WebKit/Source/platform/fonts/FontMetrics.h

Index: third_party/WebKit/Source/platform/fonts/FontMetrics.h
diff --git a/third_party/WebKit/Source/platform/fonts/FontMetrics.h b/third_party/WebKit/Source/platform/fonts/FontMetrics.h
index ce51ee9aaa7a49f9a04ef249568865c9ce5ee38d..c6c0a30e040788d6adc65ec608aa80609db29892 100644
--- a/third_party/WebKit/Source/platform/fonts/FontMetrics.h
+++ b/third_party/WebKit/Source/platform/fonts/FontMetrics.h
@@ -46,7 +46,9 @@ class FontMetrics {
         m_ascentInt(0),
         m_descentInt(0),
         m_hasXHeight(false),
-        m_hasZeroWidth(false) {}
+        m_hasZeroWidth(false),
+        m_visualOverflowAdjustmentForAscent(0),
+        m_visualOverflowAdjustmentForDescent(0) {}
 
   unsigned unitsPerEm() const { return m_unitsPerEm; }
   void setUnitsPerEm(unsigned unitsPerEm) { m_unitsPerEm = unitsPerEm; }
@@ -60,6 +62,8 @@ class FontMetrics {
   void setAscent(float ascent) {
     m_ascent = ascent;
     m_ascentInt = lroundf(ascent);
+    if (m_ascentInt < ascent)
+      m_visualOverflowAdjustmentForAscent++;
   }
 
   float floatDescent(FontBaseline baselineType = AlphabeticBaseline) const {
@@ -71,6 +75,20 @@ class FontMetrics {
   void setDescent(float descent) {
     m_descent = descent;
     m_descentInt = lroundf(descent);
+    if (m_descentInt < descent)
+      m_visualOverflowAdjustmentForDescent++;
+  }
+
+  void setVisualOverflowAdjustments(int ascentAdjustment,
+                                    int descentAdjustment) {
+    m_visualOverflowAdjustmentForAscent = ascentAdjustment;
+    m_visualOverflowAdjustmentForDescent = descentAdjustment;
+  }
+  int visualOverflowAdjustmentForAscent() const {
+    return m_visualOverflowAdjustmentForAscent;
+  }
+  int visualOverflowAdjustmentForDescent() const {
+    return m_visualOverflowAdjustmentForDescent;
   }
 
   float floatHeight(FontBaseline baselineType = AlphabeticBaseline) const {
@@ -167,6 +185,8 @@ class FontMetrics {
     m_hasXHeight = false;
     m_underlinethickness = 0;
     m_underlinePosition = 0;
+    m_visualOverflowAdjustmentForAscent = 0;
+    m_visualOverflowAdjustmentForDescent = 0;
   }
 
   unsigned m_unitsPerEm;
@@ -182,6 +202,12 @@ class FontMetrics {
   int m_descentInt;
   bool m_hasXHeight;
   bool m_hasZeroWidth;
+
+  // These are set to non-zero when ascent or descent is rounded to be smaller
+  // than the actual ascent or descent. Should consider these adjustments when
+  // calculating visual overflows.
+  int m_visualOverflowAdjustmentForAscent;
+  int m_visualOverflowAdjustmentForDescent;
 };
 
 }  // namespace blink