content/common/font_cache_dispatcher_win.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 "content/common/font_cache_dispatcher_win.h"
   6
   7 #include <map>
   8 #include <vector>
   9
  10 #include "base/logging.h"
  11 #include "base/profiler/scoped_tracker.h"
  12 #include "base/strings/string16.h"
  13 #include "content/common/child_process_messages.h"
  14
  15 namespace content {
  16 namespace {
  17 typedef std::vector<base::string16> FontNameVector;
  18 typedef std::map<FontCacheDispatcher*, FontNameVector> DispatcherToFontNames;
  19
  20 class FontCache {
  21  public:
  22   static FontCache* GetInstance() {
  23     return Singleton<FontCache>::get();
  24   }
  25
  26   void PreCacheFont(const LOGFONT& font, FontCacheDispatcher* dispatcher) {
  27     // TODO(ananta): Remove ScopedTracker below once crbug.com/90127 is fixed.
  28     tracked_objects::ScopedTracker tracking_profile(
  29         FROM_HERE_WITH_EXPLICIT_FUNCTION("90127 FontCache::PreCacheFont"));
  30
  31     typedef std::map<base::string16, FontCache::CacheElement> FontNameToElement;
  32
  33     base::AutoLock lock(mutex_);
  34
  35     // Fetch the font into memory.
  36     // No matter the font is cached or not, we load it to avoid GDI swapping out
  37     // that font file.
  38     HDC hdc = GetDC(NULL);
  39     HFONT font_handle = CreateFontIndirect(&font);
  40     DCHECK(NULL != font_handle);
  41
  42     HGDIOBJ old_font = SelectObject(hdc, font_handle);
  43     DCHECK(NULL != old_font);
  44
  45     TEXTMETRIC tm;
  46     BOOL ret = GetTextMetrics(hdc, &tm);
  47     DCHECK(ret);
  48
  49     base::string16 font_name = font.lfFaceName;
  50     int ref_count_inc = 1;
  51     FontNameVector::iterator it =
  52         std::find(dispatcher_font_map_[dispatcher].begin(),
  53                   dispatcher_font_map_[dispatcher].end(),
  54                   font_name);
  55     if (it == dispatcher_font_map_[dispatcher].end()) {
  56       // Requested font is new to cache.
  57       dispatcher_font_map_[dispatcher].push_back(font_name);
  58     } else {
  59       ref_count_inc = 0;
  60     }
  61
  62     if (cache_[font_name].ref_count_ == 0) {  // Requested font is new to cache.
  63       cache_[font_name].ref_count_ = 1;
  64     } else {  // Requested font is already in cache, release old handles.
  65       SelectObject(cache_[font_name].dc_, cache_[font_name].old_font_);
  66       DeleteObject(cache_[font_name].font_);
  67       ReleaseDC(NULL, cache_[font_name].dc_);
  68     }
  69     cache_[font_name].font_ = font_handle;
  70     cache_[font_name].dc_ = hdc;
  71     cache_[font_name].old_font_ = old_font;
  72     cache_[font_name].ref_count_ += ref_count_inc;
  73   }
  74
  75   void ReleaseCachedFonts(FontCacheDispatcher* dispatcher) {
  76     typedef std::map<base::string16, FontCache::CacheElement> FontNameToElement;
  77
  78     base::AutoLock lock(mutex_);
  79
  80     DispatcherToFontNames::iterator it;
  81     it = dispatcher_font_map_.find(dispatcher);
  82     if (it == dispatcher_font_map_.end()) {
  83       return;
  84     }
  85
  86     for (FontNameVector::iterator i = it->second.begin(), e = it->second.end();
  87                                   i != e; ++i) {
  88       FontNameToElement::iterator element;
  89       element = cache_.find(*i);
  90       if (element != cache_.end()) {
  91         --((*element).second.ref_count_);
  92       }
  93     }
  94
  95     dispatcher_font_map_.erase(it);
  96     for (FontNameToElement::iterator i = cache_.begin(); i != cache_.end(); ) {
  97       if (i->second.ref_count_ == 0) {
  98         cache_.erase(i++);
  99       } else {
 100         ++i;
 101       }
 102     }
 103   }
 104
 105  private:
 106   struct CacheElement {
 107     CacheElement()
 108         : font_(NULL), old_font_(NULL), dc_(NULL), ref_count_(0) {
 109     }
 110
 111     ~CacheElement() {
 112       if (font_) {
 113         if (dc_ && old_font_) {
 114           SelectObject(dc_, old_font_);
 115         }
 116         DeleteObject(font_);
 117       }
 118       if (dc_) {
 119         ReleaseDC(NULL, dc_);
 120       }
 121     }
 122
 123     HFONT font_;
 124     HGDIOBJ old_font_;
 125     HDC dc_;
 126     int ref_count_;
 127   };
 128   friend struct DefaultSingletonTraits<FontCache>;
 129
 130   FontCache() {
 131   }
 132
 133   std::map<base::string16, CacheElement> cache_;
 134   DispatcherToFontNames dispatcher_font_map_;
 135   base::Lock mutex_;
 136
 137   DISALLOW_COPY_AND_ASSIGN(FontCache);
 138 };
 139
 140 }
 141
 142 FontCacheDispatcher::FontCacheDispatcher()
 143     : sender_(NULL) {
 144 }
 145
 146 bool FontCacheDispatcher::Send(IPC::Message* message) {
 147   if (sender_)
 148     return sender_->Send(message);
 149
 150   delete message;
 151   return false;
 152 }
 153
 154 FontCacheDispatcher::~FontCacheDispatcher() {
 155 }
 156
 157 void FontCacheDispatcher::OnFilterAdded(IPC::Sender* sender) {
 158   sender_ = sender;
 159 }
 160
 161 bool FontCacheDispatcher::OnMessageReceived(const IPC::Message& message) {
 162   bool handled = true;
 163   IPC_BEGIN_MESSAGE_MAP(FontCacheDispatcher, message)
 164     IPC_MESSAGE_HANDLER(ChildProcessHostMsg_PreCacheFont, OnPreCacheFont)
 165     IPC_MESSAGE_HANDLER(ChildProcessHostMsg_ReleaseCachedFonts,
 166                         OnReleaseCachedFonts)
 167     IPC_MESSAGE_UNHANDLED(handled = false)
 168   IPC_END_MESSAGE_MAP()
 169   return handled;
 170 }
 171
 172 void FontCacheDispatcher::OnChannelClosing() {
 173   sender_ = NULL;
 174 }
 175
 176 void FontCacheDispatcher::OnPreCacheFont(const LOGFONT& font) {
 177   // If a child process is running in a sandbox, GetTextMetrics()
 178   // can sometimes fail. If a font has not been loaded
 179   // previously, GetTextMetrics() will try to load the font
 180   // from the font file. However, the sandboxed process does
 181   // not have permissions to access any font files and
 182   // the call fails. So we make the browser pre-load the
 183   // font for us by using a dummy call to GetTextMetrics of
 184   // the same font.
 185   // This means the browser process just loads the font into memory so that
 186   // when GDI attempt to query that font info in child process, it does not
 187   // need to load that file, hence no permission issues there.  Therefore,
 188   // when a font is asked to be cached, we always recreates the font object
 189   // to avoid the case that an in-cache font is swapped out by GDI.
 190   FontCache::GetInstance()->PreCacheFont(font, this);
 191 }
 192
 193 void FontCacheDispatcher::OnReleaseCachedFonts() {
 194   // Release cached fonts that requested from a pid by decrementing the ref
 195   // count.  When ref count is zero, the handles are released.
 196   FontCache::GetInstance()->ReleaseCachedFonts(this);
 197 }
 198
 199 }  // namespace content