ui/gfx/platform_font_pango.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/gfx/platform_font_pango.h"
   6
   7 #include <fontconfig/fontconfig.h>
   8 #include <pango/pango.h>
   9
  10 #include <algorithm>
  11 #include <string>
  12
  13 #include "base/logging.h"
  14 #include "base/strings/string_piece.h"
  15 #include "base/strings/string_split.h"
  16 #include "base/strings/utf_string_conversions.h"
  17 #include "third_party/skia/include/core/SkPaint.h"
  18 #include "third_party/skia/include/core/SkTypeface.h"
  19 #include "ui/gfx/canvas.h"
  20 #include "ui/gfx/font.h"
  21 #include "ui/gfx/pango_util.h"
  22
  23 #if defined(TOOLKIT_GTK)
  24 #include <gdk/gdk.h>
  25 #include <gtk/gtk.h>
  26 #endif
  27
  28 namespace {
  29
  30 // The font family name which is used when a user's application font for
  31 // GNOME/KDE is a non-scalable one. The name should be listed in the
  32 // IsFallbackFontAllowed function in skia/ext/SkFontHost_fontconfig_direct.cpp.
  33 const char* kFallbackFontFamilyName = "sans";
  34
  35 // Returns the available font family that best (in FontConfig's eyes) matches
  36 // the supplied list of family names.
  37 std::string FindBestMatchFontFamilyName(
  38     const std::vector<std::string>& family_names) {
  39   FcPattern* pattern = FcPatternCreate();
  40   for (std::vector<std::string>::const_iterator it = family_names.begin();
  41        it != family_names.end(); ++it) {
  42     FcValue fcvalue;
  43     fcvalue.type = FcTypeString;
  44     fcvalue.u.s = reinterpret_cast<const FcChar8*>(it->c_str());
  45     FcPatternAdd(pattern, FC_FAMILY, fcvalue, FcTrue /* append */);
  46   }
  47
  48   FcConfigSubstitute(0, pattern, FcMatchPattern);
  49   FcDefaultSubstitute(pattern);
  50   FcResult result;
  51   FcPattern* match = FcFontMatch(0, pattern, &result);
  52   DCHECK(match) << "Could not find font";
  53   FcChar8* match_family = NULL;
  54   FcPatternGetString(match, FC_FAMILY, 0, &match_family);
  55   std::string font_family(reinterpret_cast<char*>(match_family));
  56   FcPatternDestroy(pattern);
  57   FcPatternDestroy(match);
  58   return font_family;
  59 }
  60
  61 }  // namespace
  62
  63 namespace gfx {
  64
  65 // static
  66 Font* PlatformFontPango::default_font_ = NULL;
  67
  68 #if defined(OS_CHROMEOS)
  69 // static
  70 std::string* PlatformFontPango::default_font_description_ = NULL;
  71 #endif
  72
  73 ////////////////////////////////////////////////////////////////////////////////
  74 // PlatformFontPango, public:
  75
  76 PlatformFontPango::PlatformFontPango() {
  77   if (default_font_ == NULL) {
  78     std::string font_name = GetDefaultFont();
  79
  80     ScopedPangoFontDescription desc(
  81         pango_font_description_from_string(font_name.c_str()));
  82     default_font_ = new Font(desc.get());
  83
  84     DCHECK(default_font_);
  85   }
  86
  87   InitFromPlatformFont(
  88       static_cast<PlatformFontPango*>(default_font_->platform_font()));
  89 }
  90
  91 PlatformFontPango::PlatformFontPango(NativeFont native_font) {
  92   std::vector<std::string> family_names;
  93   base::SplitString(pango_font_description_get_family(native_font), ',',
  94                     &family_names);
  95   std::string font_family = FindBestMatchFontFamilyName(family_names);
  96   InitWithNameAndSize(font_family, gfx::GetPangoFontSizeInPixels(native_font));
  97
  98   int style = 0;
  99   if (pango_font_description_get_weight(native_font) == PANGO_WEIGHT_BOLD) {
 100     // TODO(davemoore) What should we do about other weights? We currently
 101     // only support BOLD.
 102     style |= gfx::Font::BOLD;
 103   }
 104   if (pango_font_description_get_style(native_font) == PANGO_STYLE_ITALIC) {
 105     // TODO(davemoore) What about PANGO_STYLE_OBLIQUE?
 106     style |= gfx::Font::ITALIC;
 107   }
 108   if (style != 0)
 109     style_ = style;
 110 }
 111
 112 PlatformFontPango::PlatformFontPango(const std::string& font_name,
 113                                      int font_size) {
 114   InitWithNameAndSize(font_name, font_size);
 115 }
 116
 117 double PlatformFontPango::underline_position() const {
 118   const_cast<PlatformFontPango*>(this)->InitPangoMetrics();
 119   return underline_position_pixels_;
 120 }
 121
 122 double PlatformFontPango::underline_thickness() const {
 123   const_cast<PlatformFontPango*>(this)->InitPangoMetrics();
 124   return underline_thickness_pixels_;
 125 }
 126
 127 ////////////////////////////////////////////////////////////////////////////////
 128 // PlatformFontPango, PlatformFont implementation:
 129
 130 // static
 131 void PlatformFontPango::ReloadDefaultFont() {
 132   delete default_font_;
 133   default_font_ = NULL;
 134 }
 135
 136 #if defined(OS_CHROMEOS)
 137 // static
 138 void PlatformFontPango::SetDefaultFontDescription(
 139     const std::string& font_description) {
 140   delete default_font_description_;
 141   default_font_description_ = new std::string(font_description);
 142 }
 143
 144 #endif
 145
 146 Font PlatformFontPango::DeriveFont(int size_delta, int style) const {
 147   // If the delta is negative, if must not push the size below 1
 148   if (size_delta < 0)
 149     DCHECK_LT(-size_delta, font_size_pixels_);
 150
 151   if (style == style_) {
 152     // Fast path, we just use the same typeface at a different size
 153     return Font(new PlatformFontPango(typeface_,
 154                                       font_family_,
 155                                       font_size_pixels_ + size_delta,
 156                                       style_));
 157   }
 158
 159   // If the style has changed we may need to load a new face
 160   int skstyle = SkTypeface::kNormal;
 161   if (gfx::Font::BOLD & style)
 162     skstyle |= SkTypeface::kBold;
 163   if (gfx::Font::ITALIC & style)
 164     skstyle |= SkTypeface::kItalic;
 165
 166   skia::RefPtr<SkTypeface> typeface = skia::AdoptRef(
 167       SkTypeface::CreateFromName(
 168           font_family_.c_str(),
 169           static_cast<SkTypeface::Style>(skstyle)));
 170
 171   return Font(new PlatformFontPango(typeface,
 172                                     font_family_,
 173                                     font_size_pixels_ + size_delta,
 174                                     style));
 175 }
 176
 177 int PlatformFontPango::GetHeight() const {
 178   return height_pixels_;
 179 }
 180
 181 int PlatformFontPango::GetBaseline() const {
 182   return ascent_pixels_;
 183 }
 184
 185 int PlatformFontPango::GetCapHeight() const {
 186   // Return the ascent as an approximation because Pango doesn't support cap
 187   // height.
 188   // TODO(yukishiino): Come up with a better approximation of cap height, or
 189   // support cap height metrics.  Another option is to have a hard-coded table
 190   // of cap height for major fonts used in Chromium/Chrome.
 191   // See http://crbug.com/249507
 192   return ascent_pixels_;
 193 }
 194
 195 int PlatformFontPango::GetAverageCharacterWidth() const {
 196   const_cast<PlatformFontPango*>(this)->InitPangoMetrics();
 197   return SkScalarRound(average_width_pixels_);
 198 }
 199
 200 int PlatformFontPango::GetStringWidth(const base::string16& text) const {
 201   return Canvas::GetStringWidth(text,
 202                                 Font(const_cast<PlatformFontPango*>(this)));
 203 }
 204
 205 int PlatformFontPango::GetExpectedTextWidth(int length) const {
 206   double char_width = const_cast<PlatformFontPango*>(this)->GetAverageWidth();
 207   return round(static_cast<float>(length) * char_width);
 208 }
 209
 210 int PlatformFontPango::GetStyle() const {
 211   return style_;
 212 }
 213
 214 std::string PlatformFontPango::GetFontName() const {
 215   return font_family_;
 216 }
 217
 218 int PlatformFontPango::GetFontSize() const {
 219   return font_size_pixels_;
 220 }
 221
 222 NativeFont PlatformFontPango::GetNativeFont() const {
 223   PangoFontDescription* pfd = pango_font_description_new();
 224   pango_font_description_set_family(pfd, GetFontName().c_str());
 225   // Set the absolute size to avoid overflowing UI elements.
 226   // pango_font_description_set_absolute_size() takes a size in Pango units.
 227   // There are PANGO_SCALE Pango units in one device unit.  Screen output
 228   // devices use pixels as their device units.
 229   pango_font_description_set_absolute_size(
 230       pfd, font_size_pixels_ * PANGO_SCALE);
 231
 232   switch (GetStyle()) {
 233     case gfx::Font::NORMAL:
 234       // Nothing to do, should already be PANGO_STYLE_NORMAL.
 235       break;
 236     case gfx::Font::BOLD:
 237       pango_font_description_set_weight(pfd, PANGO_WEIGHT_BOLD);
 238       break;
 239     case gfx::Font::ITALIC:
 240       pango_font_description_set_style(pfd, PANGO_STYLE_ITALIC);
 241       break;
 242     case gfx::Font::UNDERLINE:
 243       // TODO(deanm): How to do underline?  Where do we use it?  Probably have
 244       // to paint it ourselves, see pango_font_metrics_get_underline_position.
 245       break;
 246   }
 247
 248   return pfd;
 249 }
 250
 251 ////////////////////////////////////////////////////////////////////////////////
 252 // PlatformFontPango, private:
 253
 254 PlatformFontPango::PlatformFontPango(const skia::RefPtr<SkTypeface>& typeface,
 255                                      const std::string& name,
 256                                      int size,
 257                                      int style) {
 258   InitWithTypefaceNameSizeAndStyle(typeface, name, size, style);
 259 }
 260
 261 PlatformFontPango::~PlatformFontPango() {}
 262
 263 // static
 264 std::string PlatformFontPango::GetDefaultFont() {
 265 #if !defined(TOOLKIT_GTK)
 266 #if defined(OS_CHROMEOS)
 267   // Font name must have been provided by way of SetDefaultFontDescription().
 268   CHECK(default_font_description_);
 269   return *default_font_description_;
 270 #else
 271   return "sans 10";
 272 #endif    // defined(OS_CHROMEOS)
 273 #else
 274   GtkSettings* settings = gtk_settings_get_default();
 275
 276   gchar* font_name = NULL;
 277   g_object_get(settings, "gtk-font-name", &font_name, NULL);
 278
 279   // Temporary CHECK for helping track down
 280   // http://code.google.com/p/chromium/issues/detail?id=12530
 281   CHECK(font_name) << " Unable to get gtk-font-name for default font.";
 282
 283   std::string default_font = std::string(font_name);
 284   g_free(font_name);
 285   return default_font;
 286 #endif  // !defined(TOOLKIT_GTK)
 287 }
 288
 289
 290 void PlatformFontPango::InitWithNameAndSize(const std::string& font_name,
 291                                             int font_size) {
 292   DCHECK_GT(font_size, 0);
 293   std::string fallback;
 294
 295   skia::RefPtr<SkTypeface> typeface = skia::AdoptRef(
 296           SkTypeface::CreateFromName(font_name.c_str(), SkTypeface::kNormal));
 297   if (!typeface) {
 298     // A non-scalable font such as .pcf is specified. Falls back to a default
 299     // scalable font.
 300     typeface = skia::AdoptRef(
 301         SkTypeface::CreateFromName(
 302             kFallbackFontFamilyName, SkTypeface::kNormal));
 303     CHECK(typeface) << "Could not find any font: "
 304                     << font_name
 305                     << ", " << kFallbackFontFamilyName;
 306     fallback = kFallbackFontFamilyName;
 307   }
 308
 309   InitWithTypefaceNameSizeAndStyle(typeface,
 310                                    fallback.empty() ? font_name : fallback,
 311                                    font_size,
 312                                    gfx::Font::NORMAL);
 313 }
 314
 315 void PlatformFontPango::InitWithTypefaceNameSizeAndStyle(
 316     const skia::RefPtr<SkTypeface>& typeface,
 317     const std::string& font_family,
 318     int font_size,
 319     int style) {
 320   typeface_ = typeface;
 321   font_family_ = font_family;
 322   font_size_pixels_ = font_size;
 323   style_ = style;
 324   pango_metrics_inited_ = false;
 325   average_width_pixels_ = 0.0f;
 326   underline_position_pixels_ = 0.0f;
 327   underline_thickness_pixels_ = 0.0f;
 328
 329   SkPaint paint;
 330   SkPaint::FontMetrics metrics;
 331   PaintSetup(&paint);
 332   paint.getFontMetrics(&metrics);
 333
 334   ascent_pixels_ = SkScalarCeil(-metrics.fAscent);
 335   height_pixels_ = ascent_pixels_ + SkScalarCeil(metrics.fDescent);
 336 }
 337
 338 void PlatformFontPango::InitFromPlatformFont(const PlatformFontPango* other) {
 339   typeface_ = other->typeface_;
 340   font_family_ = other->font_family_;
 341   font_size_pixels_ = other->font_size_pixels_;
 342   style_ = other->style_;
 343   height_pixels_ = other->height_pixels_;
 344   ascent_pixels_ = other->ascent_pixels_;
 345   pango_metrics_inited_ = other->pango_metrics_inited_;
 346   average_width_pixels_ = other->average_width_pixels_;
 347   underline_position_pixels_ = other->underline_position_pixels_;
 348   underline_thickness_pixels_ = other->underline_thickness_pixels_;
 349 }
 350
 351 void PlatformFontPango::PaintSetup(SkPaint* paint) const {
 352   paint->setAntiAlias(false);
 353   paint->setSubpixelText(false);
 354   paint->setTextSize(font_size_pixels_);
 355   paint->setTypeface(typeface_.get());
 356   paint->setFakeBoldText((gfx::Font::BOLD & style_) && !typeface_->isBold());
 357   paint->setTextSkewX((gfx::Font::ITALIC & style_) && !typeface_->isItalic() ?
 358                       -SK_Scalar1/4 : 0);
 359 }
 360
 361 void PlatformFontPango::InitPangoMetrics() {
 362   if (!pango_metrics_inited_) {
 363     pango_metrics_inited_ = true;
 364     ScopedPangoFontDescription pango_desc(GetNativeFont());
 365     PangoFontMetrics* pango_metrics = GetPangoFontMetrics(pango_desc.get());
 366
 367     underline_position_pixels_ =
 368         pango_font_metrics_get_underline_position(pango_metrics) /
 369         PANGO_SCALE;
 370
 371     // TODO(davemoore): Come up with a better solution.
 372     // This is a hack, but without doing this the underlines
 373     // we get end up fuzzy. So we align to the midpoint of a pixel.
 374     underline_position_pixels_ /= 2;
 375
 376     underline_thickness_pixels_ =
 377         pango_font_metrics_get_underline_thickness(pango_metrics) /
 378         PANGO_SCALE;
 379
 380     // First get the Pango-based width (converting from Pango units to pixels).
 381     const double pango_width_pixels =
 382         pango_font_metrics_get_approximate_char_width(pango_metrics) /
 383         PANGO_SCALE;
 384
 385     // Yes, this is how Microsoft recommends calculating the dialog unit
 386     // conversions.
 387     const int text_width_pixels = GetStringWidth(
 388         ASCIIToUTF16("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"));
 389     const double dialog_units_pixels = (text_width_pixels / 26 + 1) / 2;
 390     average_width_pixels_ = std::min(pango_width_pixels, dialog_units_pixels);
 391   }
 392 }
 393
 394 double PlatformFontPango::GetAverageWidth() const {
 395   const_cast<PlatformFontPango*>(this)->InitPangoMetrics();
 396   return average_width_pixels_;
 397 }
 398
 399 ////////////////////////////////////////////////////////////////////////////////
 400 // PlatformFont, public:
 401
 402 // static
 403 PlatformFont* PlatformFont::CreateDefault() {
 404   return new PlatformFontPango;
 405 }
 406
 407 // static
 408 PlatformFont* PlatformFont::CreateFromNativeFont(NativeFont native_font) {
 409   return new PlatformFontPango(native_font);
 410 }
 411
 412 // static
 413 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
 414                                                   int font_size) {
 415   return new PlatformFontPango(font_name, font_size);
 416 }
 417
 418 }  // namespace gfx