Correcting text baseline for tiny fonts

third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp

Index: third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
diff --git a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
index f2fa9f7fa472bea7b7ff7d3d04b4eb6cc8b56776..0a711eced0a571625370ce4fb8287be3535a2be4 100644
--- a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
+++ b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
@@ -756,20 +756,22 @@ TextMetrics* CanvasRenderingContext2D::measureText(const String& text) {
       true);
 
   // x direction
-  metrics->setWidth(font.width(textRun));
-  metrics->setActualBoundingBoxLeft(-textBounds.x());
-  metrics->setActualBoundingBoxRight(textBounds.maxX());
+  metrics->setWidth(SkScalarRoundToInt(font.width(textRun)));
+  metrics->setActualBoundingBoxLeft(SkScalarRoundToInt(-textBounds.x()));
+  metrics->setActualBoundingBoxRight(SkScalarRoundToInt(textBounds.maxX()));
 
   // y direction
   const FontMetrics& fontMetrics = font.getFontMetrics();
-  const float ascent = fontMetrics.floatAscent();
-  const float descent = fontMetrics.floatDescent();
-  const float baselineY = getFontBaseline(fontMetrics);
+  const float ascent = fontMetrics.ascent();
+  const float descent = fontMetrics.descent();
+  const float baselineY = SkScalarRoundToInt(getFontBaseline(fontMetrics));
 
   metrics->setFontBoundingBoxAscent(ascent - baselineY);
   metrics->setFontBoundingBoxDescent(descent + baselineY);
-  metrics->setActualBoundingBoxAscent(-textBounds.y() - baselineY);
-  metrics->setActualBoundingBoxDescent(textBounds.maxY() + baselineY);
+  metrics->setActualBoundingBoxAscent(SkScalarRoundToInt(-textBounds.y()) -
+                                      baselineY);
+  metrics->setActualBoundingBoxDescent(SkScalarRoundToInt(textBounds.maxY()) +
+                                       baselineY);
 
   // Note : top/bottom and ascend/descend are currently the same, so there's no
   // difference between the EM box's top and bottom and the font's ascend and
@@ -865,6 +867,7 @@ void CanvasRenderingContext2D::drawTextInternal(
       FloatRect(location.x() - fontMetrics.height() / 2,
                 location.y() - fontMetrics.ascent() - fontMetrics.lineGap(),
                 width + fontMetrics.height(), fontMetrics.lineSpacing());
+
   if (paintType == CanvasRenderingContext2DState::StrokePaintType)
     inflateStrokeRect(textRunPaintInfo.bounds);
 
@@ -898,22 +901,22 @@ const Font& CanvasRenderingContext2D::accessFont() {
   return state().font();
 }
 
-int CanvasRenderingContext2D::getFontBaseline(
+float CanvasRenderingContext2D::getFontBaseline(
     const FontMetrics& fontMetrics) const {
   switch (state().getTextBaseline()) {
     case TopTextBaseline:
-      return fontMetrics.ascent();
+      return fontMetrics.floatAscent();

[eae, 2016/10/04 20:43:11]

In CanvasRenderingContext2D::measureText you changed it from floatAscent to
ascent and here the opposite despite that fact that both (presumably) return the
float value now. We should be consistent and use the same everywhere and remove
the float version if the regular one has float precision.

[zakerinasab1, 2016/10/06 20:02:52]

Fixed.

     case HangingTextBaseline:
       // According to
       // http://wiki.apache.org/xmlgraphics-fop/LineLayout/AlignmentHandling
       // "FOP (Formatting Objects Processor) puts the hanging baseline at 80% of
       // the ascender height"
-      return (fontMetrics.ascent() * 4) / 5;
+      return (fontMetrics.floatAscent() * 4.0) / 5.0;
     case BottomTextBaseline:
     case IdeographicTextBaseline:
-      return -fontMetrics.descent();
+      return -fontMetrics.floatDescent();
     case MiddleTextBaseline:
-      return -fontMetrics.descent() + fontMetrics.height() / 2;
+      return -fontMetrics.floatDescent() + fontMetrics.height() / 2.0;
     case AlphabeticTextBaseline:
     default:
       // Do nothing.