ui/gfx/font_render_params_linux.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/font_render_params_linux.h"
   6
   7 #include "base/command_line.h"
   8 #include "base/logging.h"
   9 #include "ui/gfx/display.h"
  10 #include "ui/gfx/switches.h"
  11
  12 #include <fontconfig/fontconfig.h>
  13
  14 #if defined(OS_LINUX) && defined(USE_AURA) && !defined(OS_CHROMEOS)
  15 #include "ui/gfx/linux_font_delegate.h"
  16 #endif
  17
  18 namespace gfx {
  19
  20 namespace {
  21
  22 bool SubpixelPositioningRequested(bool renderer) {
  23   const CommandLine* cl = CommandLine::ForCurrentProcess();
  24   if (renderer) {
  25     // Text rendered by Blink in high-DPI mode is poorly-hinted unless subpixel
  26     // positioning is used (as opposed to each glyph being individually snapped
  27     // to the pixel grid).
  28     return cl->HasSwitch(switches::kEnableWebkitTextSubpixelPositioning) ||
  29            (Display::HasForceDeviceScaleFactor() &&
  30             Display::GetForcedDeviceScaleFactor() != 1.0);
  31   }
  32   return cl->HasSwitch(switches::kEnableBrowserTextSubpixelPositioning);
  33 }
  34
  35 // Initializes |params| with the system's default settings. |renderer| is true
  36 // when setting WebKit renderer defaults.
  37 void LoadDefaults(FontRenderParams* params, bool renderer) {
  38   // For non-GTK builds (read: Aura), just use reasonable hardcoded values.
  39   params->antialiasing = true;
  40   params->autohinter = true;
  41   params->use_bitmaps = true;
  42   params->hinting = FontRenderParams::HINTING_SLIGHT;
  43
  44   // Fetch default subpixel rendering settings from FontConfig.
  45   FcPattern* pattern = FcPatternCreate();
  46   FcConfigSubstitute(NULL, pattern, FcMatchPattern);
  47   FcDefaultSubstitute(pattern);
  48   FcResult result;
  49   FcPattern* match = FcFontMatch(0, pattern, &result);
  50   DCHECK(match);
  51   int fc_rgba = FC_RGBA_RGB;
  52   FcPatternGetInteger(match, FC_RGBA, 0, &fc_rgba);
  53   FcPatternDestroy(pattern);
  54   FcPatternDestroy(match);
  55
  56   switch (fc_rgba) {
  57     case FC_RGBA_RGB:
  58       params->subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_RGB;
  59       break;
  60     case FC_RGBA_BGR:
  61       params->subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_BGR;
  62       break;
  63     case FC_RGBA_VRGB:
  64       params->subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_VRGB;
  65       break;
  66     case FC_RGBA_VBGR:
  67       params->subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_VBGR;
  68       break;
  69     default:
  70       params->subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_NONE;
  71   }
  72
  73 #if defined(OS_LINUX) && defined(USE_AURA) && !defined(OS_CHROMEOS)
  74   const LinuxFontDelegate* delegate = LinuxFontDelegate::instance();
  75   if (delegate) {
  76     params->antialiasing = delegate->UseAntialiasing();
  77     params->hinting = delegate->GetHintingStyle();
  78     params->subpixel_rendering = delegate->GetSubpixelRenderingStyle();
  79   }
  80 #endif
  81
  82   params->subpixel_positioning = SubpixelPositioningRequested(renderer);
  83
  84   // To enable subpixel positioning, we need to disable hinting.
  85   if (params->subpixel_positioning)
  86     params->hinting = FontRenderParams::HINTING_NONE;
  87 }
  88
  89 }  // namespace
  90
  91 const FontRenderParams& GetDefaultFontRenderParams() {
  92   static bool loaded_defaults = false;
  93   static FontRenderParams default_params;
  94   if (!loaded_defaults)
  95     LoadDefaults(&default_params, /* renderer */ false);
  96   loaded_defaults = true;
  97   return default_params;
  98 }
  99
 100 const FontRenderParams& GetDefaultWebKitFontRenderParams() {
 101   static bool loaded_defaults = false;
 102   static FontRenderParams default_params;
 103   if (!loaded_defaults)
 104     LoadDefaults(&default_params, /* renderer */ true);
 105   loaded_defaults = true;
 106   return default_params;
 107 }
 108
 109 bool GetDefaultWebkitSubpixelPositioning() {
 110   return SubpixelPositioningRequested(true);
 111 }
 112
 113 }  // namespace gfx