src/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/SkString.h"
  19 #include "third_party/skia/include/core/SkTypeface.h"
  20 #include "ui/gfx/canvas.h"
  21 #include "ui/gfx/font.h"
  22 #include "ui/gfx/font_list.h"
  23 #include "ui/gfx/linux_font_delegate.h"
  24 #include "ui/gfx/pango_util.h"
  25 #include "ui/gfx/text_utils.h"
  26
  27 namespace {
  28
  29 // The font family name which is used when a user's application font for
  30 // GNOME/KDE is a non-scalable one. The name should be listed in the
  31 // IsFallbackFontAllowed function in skia/ext/SkFontHost_fontconfig_direct.cpp.
  32 const char* kFallbackFontFamilyName = "sans";
  33
  34 // Creates a SkTypeface for the passed-in Font::FontStyle and family. If a
  35 // fallback typeface is used instead of the requested family, |family| will be
  36 // updated to contain the fallback's family name.
  37 skia::RefPtr<SkTypeface> CreateSkTypeface(int style, std::string* family) {
  38   DCHECK(family);
  39
  40   int skia_style = SkTypeface::kNormal;
  41   if (gfx::Font::BOLD & style)
  42     skia_style |= SkTypeface::kBold;
  43   if (gfx::Font::ITALIC & style)
  44     skia_style |= SkTypeface::kItalic;
  45
  46   skia::RefPtr<SkTypeface> typeface = skia::AdoptRef(SkTypeface::CreateFromName(
  47       family->c_str(), static_cast<SkTypeface::Style>(skia_style)));
  48   if (!typeface) {
  49     // A non-scalable font such as .pcf is specified. Fall back to a default
  50     // scalable font.
  51     typeface = skia::AdoptRef(SkTypeface::CreateFromName(
  52         kFallbackFontFamilyName, static_cast<SkTypeface::Style>(skia_style)));
  53     CHECK(typeface) << "Could not find any font: " << family << ", "
  54                     << kFallbackFontFamilyName;
  55     *family = kFallbackFontFamilyName;
  56   }
  57   return typeface;
  58 }
  59
  60 }  // namespace
  61
  62 namespace gfx {
  63
  64 // static
  65 Font* PlatformFontPango::default_font_ = NULL;
  66
  67 #if defined(OS_CHROMEOS)
  68 // static
  69 std::string* PlatformFontPango::default_font_description_ = NULL;
  70 #endif
  71
  72 ////////////////////////////////////////////////////////////////////////////////
  73 // PlatformFontPango, public:
  74
  75 PlatformFontPango::PlatformFontPango() {
  76   if (!default_font_) {
  77     scoped_ptr<ScopedPangoFontDescription> description;
  78 #if defined(OS_CHROMEOS)
  79     CHECK(default_font_description_);
  80     description.reset(
  81         new ScopedPangoFontDescription(*default_font_description_));
  82 #else
  83     const gfx::LinuxFontDelegate* delegate = gfx::LinuxFontDelegate::instance();
  84     if (delegate)
  85       description = delegate->GetDefaultPangoFontDescription();
  86 #endif
  87     if (!description || !description->get())
  88       description.reset(new ScopedPangoFontDescription("sans 10"));
  89     default_font_ = new Font(description->get());
  90   }
  91
  92   InitFromPlatformFont(
  93       static_cast<PlatformFontPango*>(default_font_->platform_font()));
  94 }
  95
  96 PlatformFontPango::PlatformFontPango(NativeFont native_font) {
  97   FontRenderParamsQuery query(false);
  98   base::SplitString(pango_font_description_get_family(native_font), ',',
  99                     &query.families);
 100
 101   const int pango_size =
 102       pango_font_description_get_size(native_font) / PANGO_SCALE;
 103   if (pango_font_description_get_size_is_absolute(native_font))
 104     query.pixel_size = pango_size;
 105   else
 106     query.point_size = pango_size;
 107
 108   query.style = gfx::Font::NORMAL;
 109   // TODO(davemoore): Support weights other than bold?
 110   if (pango_font_description_get_weight(native_font) == PANGO_WEIGHT_BOLD)
 111     query.style |= gfx::Font::BOLD;
 112   // TODO(davemoore): What about PANGO_STYLE_OBLIQUE?
 113   if (pango_font_description_get_style(native_font) == PANGO_STYLE_ITALIC)
 114     query.style |= gfx::Font::ITALIC;
 115
 116   std::string font_family;
 117   const FontRenderParams params = gfx::GetFontRenderParams(query, &font_family);
 118   InitFromDetails(skia::RefPtr<SkTypeface>(), font_family,
 119                   gfx::GetPangoFontSizeInPixels(native_font),
 120                   query.style, params);
 121 }
 122
 123 PlatformFontPango::PlatformFontPango(const std::string& font_name,
 124                                      int font_size_pixels) {
 125   FontRenderParamsQuery query(false);
 126   query.families.push_back(font_name);
 127   query.pixel_size = font_size_pixels;
 128   query.style = gfx::Font::NORMAL;
 129   InitFromDetails(skia::RefPtr<SkTypeface>(), font_name, font_size_pixels,
 130                   query.style, gfx::GetFontRenderParams(query, NULL));
 131 }
 132
 133 double PlatformFontPango::underline_position() const {
 134   const_cast<PlatformFontPango*>(this)->InitPangoMetrics();
 135   return underline_position_pixels_;
 136 }
 137
 138 double PlatformFontPango::underline_thickness() const {
 139   const_cast<PlatformFontPango*>(this)->InitPangoMetrics();
 140   return underline_thickness_pixels_;
 141 }
 142
 143 ////////////////////////////////////////////////////////////////////////////////
 144 // PlatformFontPango, PlatformFont implementation:
 145
 146 // static
 147 void PlatformFontPango::ReloadDefaultFont() {
 148   delete default_font_;
 149   default_font_ = NULL;
 150 }
 151
 152 #if defined(OS_CHROMEOS)
 153 // static
 154 void PlatformFontPango::SetDefaultFontDescription(
 155     const std::string& font_description) {
 156   delete default_font_description_;
 157   default_font_description_ = new std::string(font_description);
 158 }
 159
 160 #endif
 161
 162 Font PlatformFontPango::DeriveFont(int size_delta, int style) const {
 163   const int new_size = font_size_pixels_ + size_delta;
 164   DCHECK_GT(new_size, 0);
 165
 166   // If the style changed, we may need to load a new face.
 167   std::string new_family = font_family_;
 168   skia::RefPtr<SkTypeface> typeface =
 169       (style == style_) ? typeface_ : CreateSkTypeface(style, &new_family);
 170
 171   FontRenderParamsQuery query(false);
 172   query.families.push_back(new_family);
 173   query.pixel_size = new_size;
 174   query.style = style;
 175
 176   return Font(new PlatformFontPango(typeface, new_family, new_size, style,
 177                                     gfx::GetFontRenderParams(query, NULL)));
 178 }
 179
 180 int PlatformFontPango::GetHeight() const {
 181   return height_pixels_;
 182 }
 183
 184 int PlatformFontPango::GetBaseline() const {
 185   return ascent_pixels_;
 186 }
 187
 188 int PlatformFontPango::GetCapHeight() const {
 189   return cap_height_pixels_;
 190 }
 191
 192 int PlatformFontPango::GetExpectedTextWidth(int length) const {
 193   double char_width = const_cast<PlatformFontPango*>(this)->GetAverageWidth();
 194   return round(static_cast<float>(length) * char_width);
 195 }
 196
 197 int PlatformFontPango::GetStyle() const {
 198   return style_;
 199 }
 200
 201 std::string PlatformFontPango::GetFontName() const {
 202   return font_family_;
 203 }
 204
 205 std::string PlatformFontPango::GetActualFontNameForTesting() const {
 206   SkString family_name;
 207   typeface_->getFamilyName(&family_name);
 208   return family_name.c_str();
 209 }
 210
 211 int PlatformFontPango::GetFontSize() const {
 212   return font_size_pixels_;
 213 }
 214
 215 const FontRenderParams& PlatformFontPango::GetFontRenderParams() const {
 216   return font_render_params_;
 217 }
 218
 219 NativeFont PlatformFontPango::GetNativeFont() const {
 220   PangoFontDescription* pfd = pango_font_description_new();
 221   pango_font_description_set_family(pfd, GetFontName().c_str());
 222   // Set the absolute size to avoid overflowing UI elements.
 223   // pango_font_description_set_absolute_size() takes a size in Pango units.
 224   // There are PANGO_SCALE Pango units in one device unit.  Screen output
 225   // devices use pixels as their device units.
 226   pango_font_description_set_absolute_size(
 227       pfd, font_size_pixels_ * PANGO_SCALE);
 228
 229   switch (GetStyle()) {
 230     case gfx::Font::NORMAL:
 231       // Nothing to do, should already be PANGO_STYLE_NORMAL.
 232       break;
 233     case gfx::Font::BOLD:
 234       pango_font_description_set_weight(pfd, PANGO_WEIGHT_BOLD);
 235       break;
 236     case gfx::Font::ITALIC:
 237       pango_font_description_set_style(pfd, PANGO_STYLE_ITALIC);
 238       break;
 239     case gfx::Font::UNDERLINE:
 240       // TODO(deanm): How to do underline?  Where do we use it?  Probably have
 241       // to paint it ourselves, see pango_font_metrics_get_underline_position.
 242       break;
 243   }
 244
 245   return pfd;
 246 }
 247
 248 ////////////////////////////////////////////////////////////////////////////////
 249 // PlatformFontPango, private:
 250
 251 PlatformFontPango::PlatformFontPango(const skia::RefPtr<SkTypeface>& typeface,
 252                                      const std::string& name,
 253                                      int size_pixels,
 254                                      int style,
 255                                      const FontRenderParams& render_params) {
 256   InitFromDetails(typeface, name, size_pixels, style, render_params);
 257 }
 258
 259 PlatformFontPango::~PlatformFontPango() {}
 260
 261 void PlatformFontPango::InitFromDetails(
 262     const skia::RefPtr<SkTypeface>& typeface,
 263     const std::string& font_family,
 264     int font_size_pixels,
 265     int style,
 266     const FontRenderParams& render_params) {
 267   DCHECK_GT(font_size_pixels, 0);
 268
 269   font_family_ = font_family;
 270   typeface_ = typeface ? typeface : CreateSkTypeface(style, &font_family_);
 271
 272   font_size_pixels_ = font_size_pixels;
 273   style_ = style;
 274   font_render_params_ = render_params;
 275
 276   SkPaint paint;
 277   SkPaint::FontMetrics metrics;
 278   PaintSetup(&paint);
 279   paint.getFontMetrics(&metrics);
 280   ascent_pixels_ = SkScalarCeilToInt(-metrics.fAscent);
 281   height_pixels_ = ascent_pixels_ + SkScalarCeilToInt(metrics.fDescent);
 282   cap_height_pixels_ = SkScalarCeilToInt(metrics.fCapHeight);
 283
 284   pango_metrics_inited_ = false;
 285   average_width_pixels_ = 0.0f;
 286   underline_position_pixels_ = 0.0f;
 287   underline_thickness_pixels_ = 0.0f;
 288 }
 289
 290 void PlatformFontPango::InitFromPlatformFont(const PlatformFontPango* other) {
 291   typeface_ = other->typeface_;
 292   font_family_ = other->font_family_;
 293   font_size_pixels_ = other->font_size_pixels_;
 294   style_ = other->style_;
 295   font_render_params_ = other->font_render_params_;
 296   ascent_pixels_ = other->ascent_pixels_;
 297   height_pixels_ = other->height_pixels_;
 298   cap_height_pixels_ = other->cap_height_pixels_;
 299   pango_metrics_inited_ = other->pango_metrics_inited_;
 300   average_width_pixels_ = other->average_width_pixels_;
 301   underline_position_pixels_ = other->underline_position_pixels_;
 302   underline_thickness_pixels_ = other->underline_thickness_pixels_;
 303 }
 304
 305 void PlatformFontPango::PaintSetup(SkPaint* paint) const {
 306   paint->setAntiAlias(false);
 307   paint->setSubpixelText(false);
 308   paint->setTextSize(font_size_pixels_);
 309   paint->setTypeface(typeface_.get());
 310   paint->setFakeBoldText((gfx::Font::BOLD & style_) && !typeface_->isBold());
 311   paint->setTextSkewX((gfx::Font::ITALIC & style_) && !typeface_->isItalic() ?
 312                       -SK_Scalar1/4 : 0);
 313 }
 314
 315 void PlatformFontPango::InitPangoMetrics() {
 316   if (!pango_metrics_inited_) {
 317     pango_metrics_inited_ = true;
 318     ScopedPangoFontDescription pango_desc(GetNativeFont());
 319     PangoFontMetrics* pango_metrics = GetPangoFontMetrics(pango_desc.get());
 320
 321     underline_position_pixels_ =
 322         pango_font_metrics_get_underline_position(pango_metrics) /
 323         PANGO_SCALE;
 324
 325     // TODO(davemoore): Come up with a better solution.
 326     // This is a hack, but without doing this the underlines
 327     // we get end up fuzzy. So we align to the midpoint of a pixel.
 328     underline_position_pixels_ /= 2;
 329
 330     underline_thickness_pixels_ =
 331         pango_font_metrics_get_underline_thickness(pango_metrics) /
 332         PANGO_SCALE;
 333
 334     // First get the Pango-based width (converting from Pango units to pixels).
 335     const double pango_width_pixels =
 336         pango_font_metrics_get_approximate_char_width(pango_metrics) /
 337         PANGO_SCALE;
 338
 339     // Yes, this is how Microsoft recommends calculating the dialog unit
 340     // conversions.
 341     const int text_width_pixels = GetStringWidth(
 342         base::ASCIIToUTF16(
 343             "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"),
 344         FontList(Font(this)));
 345     const double dialog_units_pixels = (text_width_pixels / 26 + 1) / 2;
 346     average_width_pixels_ = std::min(pango_width_pixels, dialog_units_pixels);
 347   }
 348 }
 349
 350 double PlatformFontPango::GetAverageWidth() const {
 351   const_cast<PlatformFontPango*>(this)->InitPangoMetrics();
 352   return average_width_pixels_;
 353 }
 354
 355 ////////////////////////////////////////////////////////////////////////////////
 356 // PlatformFont, public:
 357
 358 // static
 359 PlatformFont* PlatformFont::CreateDefault() {
 360   return new PlatformFontPango;
 361 }
 362
 363 // static
 364 PlatformFont* PlatformFont::CreateFromNativeFont(NativeFont native_font) {
 365   return new PlatformFontPango(native_font);
 366 }
 367
 368 // static
 369 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
 370                                                   int font_size) {
 371   return new PlatformFontPango(font_name, font_size);
 372 }
 373
 374 }  // namespace gfx