Linux: calculate fractional xheight

We need to push the calculation of the x-height into Skia. For one of
the layout tests, it assumes that 2.5ex of Ahem is exactly 32px.
Previously we calculated the x-height of Ahem to be 13px, so 2.5*13 was
33px.

Now we use the 26.6 fixed point number from freetype's hinter and turn
that directly into a floating point value (x-height is the only WebKit
metric which is a floating point value).

This lets us pass LayoutTests/css2.1/t1507-c526-font-sz-02-b-a.html
(although the Windows baseline is wrong)

Review URL: http://codereview.chromium.org/13112


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@6344 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 15 insertions, 21 deletions

diff --git a/webkit/port/platform/graphics/chromium/SimpleFontDataLinux.cpp b/webkit/port/platform/graphics/chromium/SimpleFontDataLinux.cpp
index 2394c5e..433aa69 100644
--- a/webkit/port/platform/graphics/chromium/SimpleFontDataLinux.cpp
+++ b/webkit/port/platform/graphics/chromium/SimpleFontDataLinux.cpp
@@ -39,24 +39,11 @@ void SimpleFontData::platformInit()
         m_descent = SkScalarCeil(metrics.fHeight) - m_ascent;
     }
 
-    GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(this, 0)->page();
-    if (!glyphPageZero)
-      return;
-
-    static const UChar32 x_char = 'x';
-    const Glyph x_glyph = glyphPageZero->glyphDataForCharacter(x_char).glyph;
-
-    if (x_glyph) {
-      // If the face includes a glyph for x we measure its height exactly.
-      SkRect xbox;
-
-      paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
-      paint.measureText(&x_glyph, 2, &xbox);
-
-      m_xHeight = -xbox.fTop;
+    if (metrics.fXHeight) {
+        m_xHeight = metrics.fXHeight;
     } else {
-      // hack taken from the Windows port
-      m_xHeight = static_cast<float>(m_ascent) * 0.56;
+        // hack taken from the Windows port
+        m_xHeight = static_cast<float>(m_ascent) * 0.56;
     }
 
     m_lineGap = SkScalarRound(metrics.fLeading);
@@ -71,10 +58,17 @@ void SimpleFontData::platformInit()
     if (metrics.fAvgCharWidth) {
         m_avgCharWidth = SkScalarRound(metrics.fAvgCharWidth);
     } else {
-        if (x_glyph) {
-          m_avgCharWidth = widthForGlyph(x_glyph);
-        } else {
-          m_avgCharWidth = m_xHeight;
+        m_avgCharWidth = m_xHeight;
+
+        GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(this, 0)->page();
+
+        if (glyphPageZero) {
+            static const UChar32 x_char = 'x';
+            const Glyph x_glyph = glyphPageZero->glyphDataForCharacter(x_char).glyph;
+
+            if (x_glyph) {
+                m_avgCharWidth = widthForGlyph(x_glyph);
+            }
         }
     }
 }