ui/gfx/win/direct_write.cc

   1 // Copyright 2014 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/win/direct_write.h"
   6
   7 #include <dwrite.h>
   8
   9 #include "base/basictypes.h"
  10 #include "base/command_line.h"
  11 #include "base/metrics/field_trial.h"
  12 #include "base/win/registry.h"
  13 #include "base/win/scoped_comptr.h"
  14 #include "base/win/windows_version.h"
  15 #include "skia/ext/fontmgr_default_win.h"
  16 #include "third_party/skia/include/ports/SkTypeface_win.h"
  17 #include "ui/gfx/platform_font_win.h"
  18 #include "ui/gfx/switches.h"
  19 #include "ui/gfx/win/dpi.h"
  20
  21 namespace gfx {
  22 namespace win {
  23
  24 namespace {
  25
  26 static bool dwrite_enabled = false;
  27
  28 }
  29
  30 bool ShouldUseDirectWrite() {
  31   // If the flag is currently on, and we're on Win7 or above, we enable
  32   // DirectWrite. Skia does not require the additions to DirectWrite in QFE
  33   // 2670838, but a simple 'better than XP' check is not enough.
  34   if (base::win::GetVersion() < base::win::VERSION_WIN7)
  35     return false;
  36
  37   base::win::OSInfo::VersionNumber os_version =
  38       base::win::OSInfo::GetInstance()->version_number();
  39   if ((os_version.major == 6) && (os_version.minor == 1)) {
  40     // We can't use DirectWrite for pre-release versions of Windows 7.
  41     if (os_version.build < 7600)
  42       return false;
  43   }
  44   // If forced off, don't use it.
  45   const base::CommandLine& command_line =
  46       *base::CommandLine::ForCurrentProcess();
  47   if (command_line.HasSwitch(switches::kDisableDirectWrite))
  48     return false;
  49
  50   // Can't use GDI on HiDPI.
  51   if (gfx::GetDPIScale() > 1.0f)
  52     return true;
  53
  54   // Otherwise, check the field trial.
  55   const std::string group_name =
  56       base::FieldTrialList::FindFullName("DirectWrite");
  57   return group_name != "Disabled";
  58 }
  59
  60 void MaybeInitializeDirectWrite() {
  61   static bool tried_dwrite_initialize = false;
  62   if (tried_dwrite_initialize)
  63     return;
  64   tried_dwrite_initialize = true;
  65
  66   if (!ShouldUseDirectWrite() ||
  67       base::CommandLine::ForCurrentProcess()->HasSwitch(
  68           switches::kDisableDirectWriteForUI) ||
  69       base::CommandLine::ForCurrentProcess()->HasSwitch(
  70           switches::kDisableHarfBuzzRenderText)) {
  71     return;
  72   }
  73
  74   using DWriteCreateFactoryProc = decltype(DWriteCreateFactory)*;
  75   HMODULE dwrite_dll = LoadLibraryW(L"dwrite.dll");
  76   if (!dwrite_dll)
  77     return;
  78
  79   DWriteCreateFactoryProc dwrite_create_factory_proc =
  80       reinterpret_cast<DWriteCreateFactoryProc>(
  81           GetProcAddress(dwrite_dll, "DWriteCreateFactory"));
  82   // Not finding the DWriteCreateFactory function indicates a corrupt dll.
  83   if (!dwrite_create_factory_proc)
  84     return;
  85
  86   base::win::ScopedComPtr<IDWriteFactory> factory;
  87
  88   // Failure to create the DirectWrite factory indicates a corrupt dll.
  89   if (FAILED(dwrite_create_factory_proc(
  90           DWRITE_FACTORY_TYPE_SHARED,
  91         __uuidof(IDWriteFactory),
  92         reinterpret_cast<IUnknown**>(factory.Receive()))))
  93     return;
  94
  95   // The skia call to create a new DirectWrite font manager instance can fail
  96   // if we are unable to get the system font collection from the DirectWrite
  97   // factory. The GetSystemFontCollection method in the IDWriteFactory
  98   // interface fails with E_INVALIDARG on certain Windows 7 gold versions
  99   // (6.1.7600.*). We should just use GDI in these cases.
 100   SkFontMgr* direct_write_font_mgr = SkFontMgr_New_DirectWrite(factory.get());
 101   if (!direct_write_font_mgr)
 102     return;
 103   dwrite_enabled = true;
 104   SetDefaultSkiaFactory(direct_write_font_mgr);
 105   gfx::PlatformFontWin::SetDirectWriteFactory(factory.get());
 106 }
 107
 108 bool IsDirectWriteEnabled() {
 109   return dwrite_enabled;
 110 }
 111
 112 }  // namespace win
 113 }  // namespace gfx