Match Windows font metrics on Linux.

webkit/port/platform/graphics/chromium/SimpleFontDataLinux.cpp

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "SimpleFontData.h"
 
 #include "Font.h"
 #include "FontCache.h"
 #include "FloatRect.h"
@@ skipping 11 matching lines @@
 static const float kSmallCapsFraction = 0.7f;
 
 void SimpleFontData::platformInit()
 {
     SkPaint paint;
     SkPaint::FontMetrics metrics;
 
     m_font.setupPaint(&paint);
     paint.getFontMetrics(&metrics);
 
-    // use ceil instead of round to favor descent, given a lot of accidental
-    // clipping of descenders (e.g. 14pt 'g') in textedit fields
-    const int descent = SkScalarCeil(metrics.fDescent);
-    const int span = SkScalarRound(metrics.fDescent - metrics.fAscent);
-    const int ascent = span - descent;
-
-    m_ascent = ascent;
-    m_descent = descent;
+    // Beware those who step here: This code is designed to match Win32 font
+    // metrics *exactly*.
+    m_ascent = SkScalarCeil(-metrics.fAscent);
+    m_descent = SkScalarCeil(metrics.fDescent);
     m_xHeight = SkScalarToFloat(-metrics.fAscent) * 0.56f;   // hack I stole from the Windows port
-    m_lineSpacing = ascent + descent;
-    m_lineGap = SkScalarRound(metrics.fLeading);
+    m_lineGap = SkScalarCeil(metrics.fLeading);
+    m_lineSpacing = m_ascent + m_descent + m_lineGap;
 
     // In WebKit/WebCore/platform/graphics/SimpleFontData.cpp, m_spaceWidth is
     // calculated for us, but we need to calculate m_maxCharWidth and
     // m_avgCharWidth in order for text entry widgets to be sized correctly.
     // Skia doesn't expose either of these so we calculate them ourselves
 
     GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(this, 0)->page();
     if (!glyphPageZero)
       return;
 
@@ skipping 56 matching lines @@
 
     m_font.setupPaint(&paint);
 
     paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
     SkScalar width = paint.measureText(&glyph, 2);
     
     return SkScalarToFloat(width);
 }
 
 }  // namespace WebCore