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

src/ports/SkFontHost_mac.cpp

Index: src/ports/SkFontHost_mac.cpp
diff --git a/src/ports/SkFontHost_mac.cpp b/src/ports/SkFontHost_mac.cpp
index ac0e365e2ef1658e04349a18b76f1cf4a579e43f..35815b60b6eb2c45cee91dd12ab9b8a70395bc98 100755
--- a/src/ports/SkFontHost_mac.cpp
+++ b/src/ports/SkFontHost_mac.cpp
@@ -1379,6 +1379,18 @@ void SkScalerContext_Mac::generateFontMetrics(SkPaint::FontMetrics* mx,
     theMetrics.fXMin         = CGToScalar( CGRectGetMinX_inline(theBounds));
     theMetrics.fXMax         = CGToScalar( CGRectGetMaxX_inline(theBounds));
     theMetrics.fXHeight      = CGToScalar( CTFontGetXHeight(fCTFont));
+    theMetrics.fUnderlineThickness = CGToScalar( CTFontGetUnderlineThickness(fCTFont));
+    theMetrics.fUnderlinePosition = CGToScalar( CTFontGetUnderlinePosition(fCTFont));
+
+    if(!theMetrics.fUnderlineThickness)

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

There is no reason for any of these tests; in this case we must just always set
that we trust these as CoreText only supports fonts which have this information.
Essentially, CoreText is claiming that these values are valid. If it returns a
value of 0, we still need to trust that, as it's perfectly valid to have the
underline position on the baseline.

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

Okey, will make changes.

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

+        theMetrics.unsetFontMetricsFlag(SkPaint::FontMetrics::kUnderlineThinknessIsValid_FontMetricFlag);
+    else
+        theMetrics.setFontMetricsFlag(SkPaint::FontMetrics::kUnderlineThinknessIsValid_FontMetricFlag);
+
+    if(!theMetrics.fUnderlinePosition)
+        theMetrics.unsetFontMetricsFlag(SkPaint::FontMetrics::kUnderlinePositionIsValid_FontMetricsflag);
+    else
+        theMetrics.setFontMetricsFlag(SkPaint::FontMetrics::kUnderlinePositionIsValid_FontMetricsflag);
 
     if (mx != NULL) {
         *mx = theMetrics;