Clamp the max size of fonts used by skia/chrome canvas.

app/gfx/font_skia.cc

 // 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 "app/gfx/font.h"
 
 #include <gdk/gdk.h>
 #include <map>
 #include <pango/pango.h>
 
 #include "app/gfx/canvas.h"
 #include "base/logging.h"
 #include "base/string_piece.h"
 #include "base/sys_string_conversions.h"
 #include "third_party/skia/include/core/SkTypeface.h"
 #include "third_party/skia/include/core/SkPaint.h"
 
 namespace {
 
 // The font family name which is used when a user's application font for
 // GNOME/KDE is a non-scalable one. The name should be listed in the
 // IsFallbackFontAllowed function in skia/ext/SkFontHost_fontconfig_direct.cpp.
 const char* kFallbackFontFamilyName = "sans";
 
-// Pango scales font sizes. This returns the scale factor. See
-// pango_cairo_context_set_resolution for details.
-// NOTE: this isn't entirely accurate, in that Pango also consults the
-// FC_PIXEL_SIZE first (see get_font_size in pangocairo-fcfont), but this
-// seems to give us the same sizes as used by Pango for all our fonts in both
-// English and Thia.
-static double GetPangoScaleFactor() {
-  static float scale_factor = 0;
-  static bool determined_scale = false;
-  if (!determined_scale) {
-    PangoContext* context = gdk_pango_context_get();
-    scale_factor = pango_cairo_context_get_resolution(context);
-    g_object_unref(context);
-    if (scale_factor <= 0)
-      scale_factor = 1;
-    else
-      scale_factor /= 72.0;
-    determined_scale = true;
-  }
-  return scale_factor;
-}
-
 // Retrieves the pango metrics for a pango font description. Caches the metrics
 // and never frees them. The metrics objects are relatively small and
 // very expensive to look up.
 static PangoFontMetrics* GetPangoFontMetrics(PangoFontDescription* desc) {
   static std::map<int, PangoFontMetrics*>* desc_to_metrics = NULL;
   static PangoContext* context = NULL;
 
   if (!context) {
     context = gdk_pango_context_get_for_screen(gdk_screen_get_default());
     pango_context_set_language(context, pango_language_get_default());
@@ skipping 126 matching lines @@
       base::SysWideToUTF8(font_family_).c_str(),
       static_cast<SkTypeface::Style>(skstyle));
   SkAutoUnref tf_helper(tf);
 
   return Font(tf, font_family_, font_size_ + size_delta, style);
 }
 
 void Font::PaintSetup(SkPaint* paint) const {
   paint->setAntiAlias(false);
   paint->setSubpixelText(false);
-  paint->setTextSize(SkFloatToScalar(font_size_ * GetPangoScaleFactor()));
+  paint->setTextSize(SkFloatToScalar(font_size_ * Font::GetPangoScaleFactor()));
   paint->setTypeface(typeface_);
   paint->setFakeBoldText((BOLD & style_) && !typeface_->isBold());
   paint->setTextSkewX((ITALIC & style_) && !typeface_->isItalic() ?
                       -SK_Scalar1/4 : 0);
 }
 
 int Font::GetStringWidth(const std::wstring& text) const {
   int width = 0, height = 0;
 
   Canvas::SizeStringInt(text, *this, &width, &height, 0);
@@ skipping 64 matching lines @@
 
 int Font::FontSize() {
   return font_size_;
 }
 
 NativeFont Font::nativeFont() const {
   return typeface_;
 }
 
 }  // namespace gfx