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