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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/public/common/font_cache_dispatcher_win.h"
#include <map>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "base/containers/contains.h"
#include "base/logging.h"
#include "base/memory/singleton.h"
#include "base/numerics/checked_math.h"
#include "base/thread_annotations.h"
#include "mojo/public/cpp/bindings/self_owned_receiver.h"
namespace content {
namespace {
typedef std::vector<std::wstring> FontNameVector;
typedef std::map<FontCacheDispatcher*, FontNameVector> DispatcherToFontNames;
class FontCache {
public:
static FontCache* GetInstance() { return base::Singleton<FontCache>::get(); }
FontCache(const FontCache&) = delete;
FontCache& operator=(const FontCache&) = delete;
void PreCacheFont(const LOGFONT& font, FontCacheDispatcher* dispatcher) {
base::AutoLock lock(mutex_);
// Fetch the font into memory.
// No matter the font is cached or not, we load it to avoid GDI swapping out
// that font file.
HDC hdc = GetDC(NULL);
HFONT font_handle = CreateFontIndirect(&font);
DCHECK(NULL != font_handle);
HGDIOBJ old_font = SelectObject(hdc, font_handle);
DCHECK(NULL != old_font);
TEXTMETRIC tm;
BOOL ret = GetTextMetrics(hdc, &tm);
DCHECK(ret);
std::wstring font_name = font.lfFaceName;
bool inc_ref_count = true;
if (!base::Contains(dispatcher_font_map_[dispatcher], font_name)) {
// Requested font is new to cache.
dispatcher_font_map_[dispatcher].push_back(font_name);
} else {
inc_ref_count = false;
}
if (cache_[font_name].ref_count_.ValueOrDie() == 0) {
// Requested font is new to cache.
cache_[font_name].ref_count_ = 1;
} else { // Requested font is already in cache, release old handles.
SelectObject(cache_[font_name].dc_, cache_[font_name].old_font_);
DeleteObject(cache_[font_name].font_);
ReleaseDC(NULL, cache_[font_name].dc_);
}
cache_[font_name].font_ = font_handle;
cache_[font_name].dc_ = hdc;
cache_[font_name].old_font_ = old_font;
if (inc_ref_count) {
cache_[font_name].ref_count_++;
}
}
void ReleaseCachedFonts(FontCacheDispatcher* dispatcher) {
typedef std::map<std::wstring, FontCache::CacheElement> FontNameToElement;
base::AutoLock lock(mutex_);
DispatcherToFontNames::iterator it;
it = dispatcher_font_map_.find(dispatcher);
if (it == dispatcher_font_map_.end()) {
return;
}
for (FontNameVector::iterator i = it->second.begin(), e = it->second.end();
i != e; ++i) {
FontNameToElement::iterator element;
element = cache_.find(*i);
if (element != cache_.end()) {
--((*element).second.ref_count_);
}
}
dispatcher_font_map_.erase(it);
for (FontNameToElement::iterator i = cache_.begin(); i != cache_.end(); ) {
if (i->second.ref_count_.ValueOrDie() == 0) {
cache_.erase(i++);
} else {
++i;
}
}
}
private:
struct CacheElement {
CacheElement()
: font_(NULL), old_font_(NULL), dc_(NULL), ref_count_(0) {
}
~CacheElement() {
if (font_) {
if (dc_ && old_font_) {
SelectObject(dc_, old_font_);
}
DeleteObject(font_);
}
if (dc_) {
ReleaseDC(NULL, dc_);
}
}
HFONT font_;
HGDIOBJ old_font_;
HDC dc_;
base::CheckedNumeric<size_t> ref_count_;
};
friend struct base::DefaultSingletonTraits<FontCache>;
FontCache() {
}
std::map<std::wstring, CacheElement> cache_ GUARDED_BY(mutex_);
DispatcherToFontNames dispatcher_font_map_ GUARDED_BY(mutex_);
base::Lock mutex_;
};
} // namespace
FontCacheDispatcher::FontCacheDispatcher() {}
FontCacheDispatcher::~FontCacheDispatcher() {
}
// static
void FontCacheDispatcher::Create(
mojo::PendingReceiver<mojom::FontCacheWin> receiver) {
mojo::MakeSelfOwnedReceiver(std::make_unique<FontCacheDispatcher>(),
std::move(receiver));
}
void FontCacheDispatcher::PreCacheFont(const LOGFONT& log_font,
PreCacheFontCallback callback) {
// If a child process is running in a sandbox, GetTextMetrics()
// can sometimes fail. If a font has not been loaded
// previously, GetTextMetrics() will try to load the font
// from the font file. However, the sandboxed process does
// not have permissions to access any font files and
// the call fails. So we make the browser pre-load the
// font for us by using a dummy call to GetTextMetrics of
// the same font.
// This means the browser process just loads the font into memory so that
// when GDI attempt to query that font info in child process, it does not
// need to load that file, hence no permission issues there. Therefore,
// when a font is asked to be cached, we always recreates the font object
// to avoid the case that an in-cache font is swapped out by GDI.
FontCache::GetInstance()->PreCacheFont(log_font, this);
// Run |callback| to indicate this synchronous handler finished.
std::move(callback).Run();
}
void FontCacheDispatcher::ReleaseCachedFonts() {
// Release cached fonts that requested from a pid by decrementing the ref
// count. When ref count is zero, the handles are released.
FontCache::GetInstance()->ReleaseCachedFonts(this);
}
} // namespace content
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