Adding code to calculate Underline Thickness from Font Metrics, this will be useful when Skia is us…

src/ports/SkFontHost_FreeType.cpp

Index: src/ports/SkFontHost_FreeType.cpp
diff --git a/src/ports/SkFontHost_FreeType.cpp b/src/ports/SkFontHost_FreeType.cpp
index fe32ebb42a7fe33c7e7758738cc40f26f7afaa8d..935f353208244f66572d3dfb435ab73e6e505349 100644
--- a/src/ports/SkFontHost_FreeType.cpp
+++ b/src/ports/SkFontHost_FreeType.cpp
@@ -1384,6 +1384,7 @@ void SkScalerContext_FreeType::generateFontMetrics(SkPaint::FontMetrics* mx,
 
     // pull from format-specific metrics as needed
     SkScalar ascent, descent, leading, xmin, xmax, ymin, ymax;
+    SkScalar underlineThickness, underlinePosition;
     if (face->face_flags & FT_FACE_FLAG_SCALABLE) { // scalable outline font
         ascent = -SkIntToScalar(face->ascender) / upem;
         descent = -SkIntToScalar(face->descender) / upem;
@@ -1392,6 +1393,8 @@ void SkScalerContext_FreeType::generateFontMetrics(SkPaint::FontMetrics* mx,
         xmax = SkIntToScalar(face->bbox.xMax) / upem;
         ymin = -SkIntToScalar(face->bbox.yMin) / upem;
         ymax = -SkIntToScalar(face->bbox.yMax) / upem;
+        underlineThickness = SkIntToScalar(face->underline_thickness) / upem;
+        underlinePosition = SkIntToScalar(face->underline_position) / upem;
         // we may be able to synthesize x_height and cap_height from outline
         if (!x_height) {
             FT_BBox bbox;
@@ -1416,6 +1419,8 @@ void SkScalerContext_FreeType::generateFontMetrics(SkPaint::FontMetrics* mx,
         xmax = SkIntToScalar(face->available_sizes[fStrikeIndex].width) / xppem;
         ymin = descent + leading;
         ymax = ascent - descent;
+        underlineThickness = 0;

[bungeman-skia, 2014/02/17 19:10:06]

Here is where the 'unknown' flag should be set (or the 'known' flag unset)
stating that we don't know what the value is. The entire point of having the
bitfield was to avoid using this '0 means unknown' convention.

[h.joshi, 2014/02/18 05:48:48]

Okey, will make required changes.

On 2014/02/17 19:10:06, bungeman1 wrote:

+        underlinePosition = 0;
     } else {
         goto ERROR;
     }
@@ -1447,6 +1452,8 @@ void SkScalerContext_FreeType::generateFontMetrics(SkPaint::FontMetrics* mx,
         mx->fXMax = xmax;
         mx->fXHeight = x_height;
         mx->fCapHeight = cap_height;
+        mx->fUnderlineThickness = underlineThickness;
+        mx->fUnderlinePosition = underlinePosition;
     }
     if (my) {
         my->fTop = ymax * myy;
@@ -1459,6 +1466,8 @@ void SkScalerContext_FreeType::generateFontMetrics(SkPaint::FontMetrics* mx,
         my->fXMax = xmax;
         my->fXHeight = x_height;
         my->fCapHeight = cap_height;
+        my->fUnderlineThickness = underlineThickness;
+        my->fUnderlinePosition = underlinePosition;
     }
 }