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 "ui/gfx/font_render_params.h"
   6
   7 #include "base/memory/scoped_ptr.h"
   8 #include "base/memory/singleton.h"
   9 #include "ui/gfx/win/direct_write.h"
  10 #include "ui/gfx/win/singleton_hwnd.h"
  11
  12 namespace gfx {
  13
  14 namespace {
  15
  16 // Caches font render params and updates them on system notifications.
  17 class CachedFontRenderParams : public gfx::SingletonHwnd::Observer {
  18  public:
  19   static CachedFontRenderParams* GetInstance() {
  20     return Singleton<CachedFontRenderParams>::get();
  21   }
  22
  23   const FontRenderParams& GetParams() {
  24     if (params_)
  25       return *params_;
  26
  27     params_.reset(new FontRenderParams());
  28     params_->antialiasing = false;
  29     params_->subpixel_positioning = false;
  30     params_->autohinter = false;
  31     params_->use_bitmaps = false;
  32     params_->hinting = FontRenderParams::HINTING_MEDIUM;
  33     params_->subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_NONE;
  34
  35     BOOL enabled = false;
  36     if (SystemParametersInfo(SPI_GETFONTSMOOTHING, 0, &enabled, 0) && enabled) {
  37       params_->antialiasing = true;
  38       // GDI does not support subpixel positioning.
  39       params_->subpixel_positioning = win::IsDirectWriteEnabled();
  40
  41       UINT type = 0;
  42       if (SystemParametersInfo(SPI_GETFONTSMOOTHINGTYPE, 0, &type, 0) &&
  43           type == FE_FONTSMOOTHINGCLEARTYPE) {
  44         params_->subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_RGB;
  45       }
  46     }
  47     gfx::SingletonHwnd::GetInstance()->AddObserver(this);
  48     return *params_;
  49   }
  50
  51  private:
  52   friend struct DefaultSingletonTraits<CachedFontRenderParams>;
  53
  54   CachedFontRenderParams() {}
  55   virtual ~CachedFontRenderParams() {
  56     // Can't remove the SingletonHwnd observer here since SingletonHwnd may have
  57     // been destroyed already (both singletons).
  58   }
  59
  60   virtual void OnWndProc(HWND hwnd,
  61                          UINT message,
  62                          WPARAM wparam,
  63                          LPARAM lparam) override {
  64     if (message == WM_SETTINGCHANGE) {
  65       params_.reset();
  66       gfx::SingletonHwnd::GetInstance()->RemoveObserver(this);
  67     }
  68   }
  69
  70   scoped_ptr<FontRenderParams> params_;
  71
  72   DISALLOW_COPY_AND_ASSIGN(CachedFontRenderParams);
  73 };
  74
  75 }  // namespace
  76
  77 FontRenderParams GetFontRenderParams(const FontRenderParamsQuery& query,
  78                                      std::string* family_out) {
  79   if (family_out)
  80     NOTIMPLEMENTED();
  81   // Customized font rendering settings are not supported, only defaults.
  82   return CachedFontRenderParams::GetInstance()->GetParams();
  83 }
  84
  85 }  // namespace gfx