Rework gfx::Font by moving platform-specific code into inner classes....

gfx/font_skia.cc

-// Copyright (c) 2010 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 "gfx/font.h"
-
-#include <gdk/gdk.h>
-#include <map>
-#include <pango/pango.h>
-
-#include "base/logging.h"
-#include "base/string_piece.h"
-#include "base/sys_string_conversions.h"
-#include "gfx/canvas_skia.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";
-
-// 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());
-  }
-
-  if (!desc_to_metrics) {
-    desc_to_metrics = new std::map<int, PangoFontMetrics*>();
-  }
-
-  int desc_hash = pango_font_description_hash(desc);
-  std::map<int, PangoFontMetrics*>::iterator i =
-      desc_to_metrics->find(desc_hash);
-
-  if (i == desc_to_metrics->end()) {
-    PangoFontMetrics* metrics = pango_context_get_metrics(context, desc, NULL);
-    (*desc_to_metrics)[desc_hash] = metrics;
-    return metrics;
-  } else {
-    return i->second;
-  }
-}
-
-}  // namespace
-
-namespace gfx {
-
-Font::Font(const Font& other) {
-  CopyFont(other);
-}
-
-Font& Font::operator=(const Font& other) {
-  CopyFont(other);
-  return *this;
-}
-
-Font::Font(SkTypeface* tf, const std::wstring& font_family, int font_size,
-           int style)
-    : typeface_helper_(new SkAutoUnref(tf)),
-      typeface_(tf),
-      font_family_(font_family),
-      font_size_(font_size),
-      style_(style),
-      pango_metrics_inited_(false),
-      avg_width_(0.0),
-      underline_position_(0.0),
-      underline_thickness_(0.0) {
-  tf->ref();
-  calculateMetrics();
-}
-
-void Font::calculateMetrics() {
-  SkPaint paint;
-  SkPaint::FontMetrics metrics;
-  PaintSetup(&paint);
-  paint.getFontMetrics(&metrics);
-
-  ascent_ = SkScalarCeil(-metrics.fAscent);
-  height_ = ascent_ + SkScalarCeil(metrics.fDescent);
-
-}
-
-void Font::CopyFont(const Font& other) {
-  typeface_helper_.reset(new SkAutoUnref(other.typeface_));
-  typeface_ = other.typeface_;
-  typeface_->ref();
-  font_family_ = other.font_family_;
-  font_size_ = other.font_size_;
-  style_ = other.style_;
-  height_ = other.height_;
-  ascent_ = other.ascent_;
-  pango_metrics_inited_ = other.pango_metrics_inited_;
-  avg_width_ = other.avg_width_;
-  underline_position_ = other.underline_position_;
-  underline_thickness_ = other.underline_thickness_;
-}
-
-int Font::height() const {
-  return height_;
-}
-
-int Font::baseline() const {
-  return ascent_;
-}
-
-int Font::ave_char_width() const {
-  return SkScalarRound(avg_width());
-}
-
-Font Font::CreateFont(const std::wstring& font_family, int font_size) {
-  DCHECK_GT(font_size, 0);
-  std::wstring fallback;
-
-  SkTypeface* tf = SkTypeface::CreateFromName(
-      base::SysWideToUTF8(font_family).c_str(), SkTypeface::kNormal);
-  if (!tf) {
-    // A non-scalable font such as .pcf is specified. Falls back to a default
-    // scalable font.
-    tf = SkTypeface::CreateFromName(
-        kFallbackFontFamilyName, SkTypeface::kNormal);
-    CHECK(tf) << "Could not find any font: "
-              << base::SysWideToUTF8(font_family)
-              << ", " << kFallbackFontFamilyName;
-    fallback = base::SysUTF8ToWide(kFallbackFontFamilyName);
-  }
-  SkAutoUnref tf_helper(tf);
-
-  return Font(
-      tf, fallback.empty() ? font_family : fallback, font_size, NORMAL);
-}
-
-Font Font::DeriveFont(int size_delta, int style) const {
-  // If the delta is negative, if must not push the size below 1
-  if (size_delta < 0) {
-    DCHECK_LT(-size_delta, font_size_);
-  }
-
-  if (style == style_) {
-    // Fast path, we just use the same typeface at a different size
-    return Font(typeface_, font_family_, font_size_ + size_delta, style_);
-  }
-
-  // If the style has changed we may need to load a new face
-  int skstyle = SkTypeface::kNormal;
-  if (BOLD & style)
-    skstyle |= SkTypeface::kBold;
-  if (ITALIC & style)
-    skstyle |= SkTypeface::kItalic;
-
-  SkTypeface* tf = SkTypeface::CreateFromName(
-      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_ * 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;
-  CanvasSkia::SizeStringInt(text, *this, &width, &height,
-                            gfx::Canvas::NO_ELLIPSIS);
-  return width;
-}
-
-void Font::InitPangoMetrics() {
-  if (!pango_metrics_inited_) {
-    pango_metrics_inited_ = true;
-    PangoFontDescription* pango_desc = PangoFontFromGfxFont(*this);
-    PangoFontMetrics* pango_metrics = GetPangoFontMetrics(pango_desc);
-
-    underline_position_ =
-        pango_font_metrics_get_underline_position(pango_metrics);
-    underline_position_ /= PANGO_SCALE;
-
-    // todo(davemoore) Come up with a better solution.
-    // This is a hack, but without doing this the underlines
-    // we get end up fuzzy. So we align to the midpoint of a pixel.
-    underline_position_ /= 2;
-
-    underline_thickness_ =
-        pango_font_metrics_get_underline_thickness(pango_metrics);
-    underline_thickness_ /= PANGO_SCALE;
-
-    // First get the pango based width
-    double pango_width =
-        pango_font_metrics_get_approximate_char_width(pango_metrics);
-    pango_width /= PANGO_SCALE;
-
-    // Yes, this is how Microsoft recommends calculating the dialog unit
-    // conversions.
-    int text_width = GetStringWidth(
-        L"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz");
-    double dialog_units = (text_width / 26 + 1) / 2;
-    avg_width_ = std::min(pango_width, dialog_units);
-    pango_font_description_free(pango_desc);
-  }
-}
-
-double Font::avg_width() const {
-  const_cast<Font*>(this)->InitPangoMetrics();
-  return avg_width_;
-}
-
-double Font::underline_position() const {
-  const_cast<Font*>(this)->InitPangoMetrics();
-  return underline_position_;
-}
-
-double Font::underline_thickness() const {
-  const_cast<Font*>(this)->InitPangoMetrics();
-  return underline_thickness_;
-}
-
-int Font::GetExpectedTextWidth(int length) const {
-  double char_width = const_cast<Font*>(this)->avg_width();
-  return round(static_cast<float>(length) * char_width);
-}
-
-int Font::style() const {
-  return style_;
-}
-
-const std::wstring& Font::FontName() const {
-  return font_family_;
-}
-
-int Font::FontSize() {
-  return font_size_;
-}
-
-NativeFont Font::nativeFont() const {
-  return typeface_;
-}
-
-}  // namespace gfx