Changeset 101343 in webkit

Timestamp:

Nov 29, 2011 1:42:34 AM (12 years ago)

Author:

Philippe Normand

Message:

[GTK] Improve FontMetrics accuracy
​https://bugs.webkit.org/show_bug.cgi?id=72614

Reviewed by Martin Robinson.
Patch by Nikolas Zimmermann.

• platform/graphics/freetype/FontPlatformDataFreeType.cpp:

(WebCore::setCairoFontOptionsFromFontConfigPattern):

• platform/graphics/freetype/SimpleFontDataFreeType.cpp:

(WebCore::SimpleFontData::platformInit):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/freetype/FontPlatformDataFreeType.cpp (modified) (1 diff)
• platform/graphics/freetype/SimpleFontDataFreeType.cpp (modified) (2 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2011-11-25  Philippe Normand  <pnormand@igalia.com>
+
+        [GTK] Improve FontMetrics accuracy
+        https://bugs.webkit.org/show_bug.cgi?id=72614
+
+        Reviewed by Martin Robinson.
+        Patch by Nikolas Zimmermann.
+
+        * platform/graphics/freetype/FontPlatformDataFreeType.cpp:
+        (WebCore::setCairoFontOptionsFromFontConfigPattern):
+        * platform/graphics/freetype/SimpleFontDataFreeType.cpp:
+        (WebCore::SimpleFontData::platformInit):
+
 2011-11-29  Nikolas Zimmermann  <nzimmermann@rim.com>
 

trunk/Source/WebCore/platform/graphics/freetype/FontPlatformDataFreeType.cpp

@@ -99 +99 @@
     if (FcPatternGetBool(pattern, FC_HINTING, 0, &booleanResult) == FcResultMatch && !booleanResult)
         cairo_font_options_set_hint_style(options, CAIRO_HINT_STYLE_NONE);
+
+    // Turn off text metrics hinting, which quantizes metrics to pixels in device space.
+    cairo_font_options_set_hint_metrics(options, CAIRO_HINT_METRICS_OFF);
 }
 

trunk/Source/WebCore/platform/graphics/freetype/SimpleFontDataFreeType.cpp

@@ -34 +34 @@
 #include "SimpleFontData.h"
 
+#include "FloatConversion.h"
 #include "FloatRect.h"
 #include "Font.h"
@@ -56 +57 @@
     cairo_scaled_font_extents(m_platformData.scaledFont(), &font_extents);
 
-    m_fontMetrics.setAscent(font_extents.ascent);
-    m_fontMetrics.setDescent(font_extents.descent);
+    float ascent = narrowPrecisionToFloat(font_extents.ascent);
+    float descent = narrowPrecisionToFloat(font_extents.descent);
+    float lineGap = narrowPrecisionToFloat(font_extents.height - font_extents.ascent - font_extents.descent);
 
-    // There seems to be some rounding error in cairo (or in how we
-    // use cairo) with some fonts, like DejaVu Sans Mono, which makes
-    // cairo report a height smaller than ascent + descent, which is
-    // wrong and confuses WebCore's layout system. Workaround this
-    // while we figure out what's going on.
-    float lineSpacing = font_extents.height;
-    if (lineSpacing < font_extents.ascent + font_extents.descent)
-        lineSpacing = font_extents.ascent + font_extents.descent;
+    m_fontMetrics.setAscent(ascent);
+    m_fontMetrics.setDescent(descent);
 
-    m_fontMetrics.setLineSpacing(lroundf(lineSpacing));
-    m_fontMetrics.setLineGap(lineSpacing - font_extents.ascent - font_extents.descent);
+    // Match CoreGraphics metrics.
+    m_fontMetrics.setLineSpacing(lroundf(ascent) + lroundf(descent) + lroundf(lineGap));
+    m_fontMetrics.setLineGap(lineGap);
 
     cairo_scaled_font_text_extents(m_platformData.scaledFont(), "x", &text_extents);
-    m_fontMetrics.setXHeight(text_extents.height);
+    m_fontMetrics.setXHeight(narrowPrecisionToFloat(text_extents.height));
 
     cairo_scaled_font_text_extents(m_platformData.scaledFont(), " ", &text_extents);
-    m_spaceWidth = static_cast<float>(text_extents.x_advance);
+    m_spaceWidth = narrowPrecisionToFloat(text_extents.x_advance);
     
     m_syntheticBoldOffset = m_platformData.syntheticBold() ? 1.0f : 0.f;