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

src/ports/SkFontHost_win.cpp

Index: src/ports/SkFontHost_win.cpp
diff --git a/src/ports/SkFontHost_win.cpp b/src/ports/SkFontHost_win.cpp
index 4ca0fb9181404e36c42318e095a8c8fdb081b4b1..6f329bd975649cc7f7fb85b05d58cbcb976e1372 100755
--- a/src/ports/SkFontHost_win.cpp
+++ b/src/ports/SkFontHost_win.cpp
@@ -1061,6 +1061,18 @@ void SkScalerContext_GDI::generateFontMetrics(SkPaint::FontMetrics* mx, SkPaint:
         mx->fDescent = SkIntToScalar(-otm.otmDescent);
         mx->fBottom = SkIntToScalar(otm.otmrcFontBox.right);
         mx->fLeading = SkIntToScalar(otm.otmLineGap);
+        mx->fUnderlineThickness = SkIntToScalar(otm.otmsUnderscoreSize);
+        mx->fUnderlinePosition = SkIntToScalar(otm.otmsUnderscorePosition);
+
+        if(!mx->fUnderlineThickness)

[bungeman-skia, 2014/02/19 15:39:17]

If we get here, we're only dealing with fonts which will have this information,
so these checks don't make sense, and we should just set that we trust these two
values. (Same below.) Note that the fonts which do not have this information
have already been dealt with above, and we are zeroing the entire FontMetrics
struct, so those already state not to trust these values (which is good since
they're just 0).

[h.joshi, 2014/02/19 17:12:03]

Okey, Added these checks below as "face->underline_thickness" and
"face->underline_position" can be zero. Will make changes

On 2014/02/19 15:39:17, bungeman1 wrote:

+            mx->unsetFontMetricsFlag(SkPaint::FontMetrics::kUnderlineThinknessIsValid_FontMetricFlag);
+        else
+            mx->setFontMetricsFlag(SkPaint::FontMetrics::kUnderlineThinknessIsValid_FontMetricFlag);
+
+        if(!mx->fUnderlinePosition)
+            mx->unsetFontMetricsFlag(SkPaint::FontMetrics::kUnderlinePositionIsValid_FontMetricsflag);
+        else
+            mx->setFontMetricsFlag(SkPaint::FontMetrics::kUnderlinePositionIsValid_FontMetricsflag);
     }
 
     if (my) {
@@ -1074,6 +1086,18 @@ void SkScalerContext_GDI::generateFontMetrics(SkPaint::FontMetrics* mx, SkPaint:
         my->fMaxCharWidth = SkIntToScalar(otm.otmTextMetrics.tmMaxCharWidth);
         my->fXMin = SkIntToScalar(otm.otmrcFontBox.left);
         my->fXMax = SkIntToScalar(otm.otmrcFontBox.right);
+        my->fUnderlineThickness = SkIntToScalar(otm.otmsUnderscoreSize);
+        my->fUnderlinePosition = SkIntToScalar(otm.otmsUnderscorePosition);
+
+        if(!my->fUnderlineThickness)
+            my->unsetFontMetricsFlag(SkPaint::FontMetrics::kUnderlineThinknessIsValid_FontMetricFlag);
+        else
+            my->setFontMetricsFlag(SkPaint::FontMetrics::kUnderlineThinknessIsValid_FontMetricFlag);
+
+        if(!my->fUnderlinePosition)
+            my->unsetFontMetricsFlag(SkPaint::FontMetrics::kUnderlinePositionIsValid_FontMetricsflag);
+        else
+            my->setFontMetricsFlag(SkPaint::FontMetrics::kUnderlinePositionIsValid_FontMetricsflag);
 #endif
         my->fXHeight = SkIntToScalar(otm.otmsXHeight);