ui/gfx/font_render_params_win.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 "base/bind.h"
   6 #include "base/bind_helpers.h"
   7 #include "base/files/file_path.h"
   8 #include "base/memory/scoped_ptr.h"
   9 #include "base/memory/singleton.h"
  10 #include "base/win/registry.h"
  11 #include "ui/gfx/font_render_params.h"
  12 #include "ui/gfx/win/direct_write.h"
  13 #include "ui/gfx/win/singleton_hwnd_observer.h"
  14
  15 namespace gfx {
  16
  17 namespace {
  18
  19 FontRenderParams::SubpixelRendering GetSubpixelRenderingGeometry() {
  20   DISPLAY_DEVICE display_device = {sizeof(DISPLAY_DEVICE)};
  21   for (int i = 0; EnumDisplayDevices(nullptr, i, &display_device, 0); ++i) {
  22     // TODO(scottmg): We only support the primary device currently.
  23     if (display_device.StateFlags & DISPLAY_DEVICE_PRIMARY_DEVICE) {
  24       base::FilePath trimmed =
  25           base::FilePath(display_device.DeviceName).BaseName();
  26       base::win::RegKey key(
  27           HKEY_LOCAL_MACHINE,
  28           (L"SOFTWARE\\Microsoft\\Avalon.Graphics\\" + trimmed.value()).c_str(),
  29           KEY_READ);
  30       DWORD pixel_structure;
  31       if (key.ReadValueDW(L"PixelStructure", &pixel_structure) ==
  32           ERROR_SUCCESS) {
  33         if (pixel_structure == 1)
  34           return FontRenderParams::SUBPIXEL_RENDERING_RGB;
  35         if (pixel_structure == 2)
  36           return FontRenderParams::SUBPIXEL_RENDERING_BGR;
  37       }
  38       break;
  39     }
  40   }
  41
  42   // No explicit ClearType settings, default to RGB.
  43   return FontRenderParams::SUBPIXEL_RENDERING_RGB;
  44 }
  45
  46 // Caches font render params and updates them on system notifications.
  47 class CachedFontRenderParams {
  48  public:
  49   static CachedFontRenderParams* GetInstance() {
  50     return base::Singleton<CachedFontRenderParams>::get();
  51   }
  52
  53   const FontRenderParams& GetParams() {
  54     if (params_)
  55       return *params_;
  56
  57     params_.reset(new FontRenderParams());
  58     params_->antialiasing = false;
  59     params_->subpixel_positioning = false;
  60     params_->autohinter = false;
  61     params_->use_bitmaps = false;
  62     params_->hinting = FontRenderParams::HINTING_MEDIUM;
  63     params_->subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_NONE;
  64
  65     BOOL enabled = false;
  66     if (SystemParametersInfo(SPI_GETFONTSMOOTHING, 0, &enabled, 0) && enabled) {
  67       params_->antialiasing = true;
  68       // GDI does not support subpixel positioning.
  69       params_->subpixel_positioning = win::IsDirectWriteEnabled();
  70
  71       UINT type = 0;
  72       if (SystemParametersInfo(SPI_GETFONTSMOOTHINGTYPE, 0, &type, 0) &&
  73           type == FE_FONTSMOOTHINGCLEARTYPE) {
  74         params_->subpixel_rendering = GetSubpixelRenderingGeometry();
  75       }
  76     }
  77     singleton_hwnd_observer_.reset(new SingletonHwndObserver(
  78         base::Bind(&CachedFontRenderParams::OnWndProc,
  79                    base::Unretained(this))));
  80     return *params_;
  81   }
  82
  83  private:
  84   friend struct base::DefaultSingletonTraits<CachedFontRenderParams>;
  85
  86   CachedFontRenderParams() {}
  87   ~CachedFontRenderParams() {}
  88
  89   void OnWndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
  90     if (message == WM_SETTINGCHANGE) {
  91       params_.reset();
  92       singleton_hwnd_observer_.reset(nullptr);
  93     }
  94   }
  95
  96   scoped_ptr<FontRenderParams> params_;
  97   scoped_ptr<SingletonHwndObserver> singleton_hwnd_observer_;
  98
  99   DISALLOW_COPY_AND_ASSIGN(CachedFontRenderParams);
 100 };
 101
 102 }  // namespace
 103
 104 FontRenderParams GetFontRenderParams(const FontRenderParamsQuery& query,
 105                                      std::string* family_out) {
 106   if (family_out)
 107     NOTIMPLEMENTED();
 108   // Customized font rendering settings are not supported, only defaults.
 109   return CachedFontRenderParams::GetInstance()->GetParams();
 110 }
 111
 112 }  // namespace gfx