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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/core/html/canvas/canvas_font_cache.h"
#include "third_party/blink/public/platform/platform.h"
#include "third_party/blink/renderer/core/css/parser/css_parser.h"
#include "third_party/blink/renderer/core/css/resolver/style_resolver.h"
#include "third_party/blink/renderer/core/dom/document.h"
#include "third_party/blink/renderer/core/html/canvas/html_canvas_element.h"
#include "third_party/blink/renderer/core/style/computed_style.h"
#include "third_party/blink/renderer/platform/fonts/font_cache.h"
#include "third_party/blink/renderer/platform/heap/heap.h"
#include "third_party/blink/renderer/platform/instrumentation/memory_pressure_listener.h"
namespace {
const unsigned CanvasFontCacheMaxFonts = 50;
const unsigned CanvasFontCacheMaxFontsLowEnd = 5;
const unsigned CanvasFontCacheHardMaxFonts = 250;
const unsigned CanvasFontCacheHardMaxFontsLowEnd = 20;
const unsigned CanvasFontCacheHiddenMaxFonts = 1;
const int defaultFontSize = 10;
const char defaultFontFamily[] = "sans-serif";
}
namespace blink {
CanvasFontCache::CanvasFontCache(Document& document)
: document_(&document), pruning_scheduled_(false) {
FontFamily font_family;
font_family.SetFamily(defaultFontFamily);
FontDescription default_font_description;
default_font_description.SetFamily(font_family);
default_font_description.SetSpecifiedSize(defaultFontSize);
default_font_description.SetComputedSize(defaultFontSize);
default_font_style_ = ComputedStyle::Create();
default_font_style_->SetFontDescription(default_font_description);
}
CanvasFontCache::~CanvasFontCache() {
}
unsigned CanvasFontCache::MaxFonts() {
return MemoryPressureListenerRegistry::IsLowEndDevice()
? CanvasFontCacheMaxFontsLowEnd
: CanvasFontCacheMaxFonts;
}
unsigned CanvasFontCache::HardMaxFonts() {
return document_->hidden() ? CanvasFontCacheHiddenMaxFonts
: (MemoryPressureListenerRegistry::IsLowEndDevice()
? CanvasFontCacheHardMaxFontsLowEnd
: CanvasFontCacheHardMaxFonts);
}
bool CanvasFontCache::GetFontUsingDefaultStyle(HTMLCanvasElement& element,
const String& font_string,
Font& resolved_font) {
HashMap<String, Font>::iterator i =
fonts_resolved_using_default_style_.find(font_string);
if (i != fonts_resolved_using_default_style_.end()) {
auto add_result = font_lru_list_.PrependOrMoveToFirst(font_string);
DCHECK(!add_result.is_new_entry);
resolved_font = i->value;
return true;
}
// Addition to LRU list taken care of inside parseFont
MutableCSSPropertyValueSet* parsed_style = ParseFont(font_string);
if (!parsed_style)
return false;
scoped_refptr<ComputedStyle> font_style =
ComputedStyle::Clone(*default_font_style_.get());
document_->EnsureStyleResolver().ComputeFont(element, font_style.get(),
*parsed_style);
fonts_resolved_using_default_style_.insert(font_string,
font_style->GetFont());
resolved_font = fonts_resolved_using_default_style_.find(font_string)->value;
return true;
}
MutableCSSPropertyValueSet* CanvasFontCache::ParseFont(
const String& font_string) {
MutableCSSPropertyValueSet* parsed_style;
MutableStylePropertyMap::iterator i = fetched_fonts_.find(font_string);
if (i != fetched_fonts_.end()) {
auto add_result = font_lru_list_.PrependOrMoveToFirst(font_string);
DCHECK(!add_result.is_new_entry);
parsed_style = i->value;
} else {
parsed_style =
MakeGarbageCollected<MutableCSSPropertyValueSet>(kHTMLStandardMode);
CSSParser::ParseValue(parsed_style, CSSPropertyID::kFont, font_string, true,
document_->GetSecureContextMode());
if (parsed_style->IsEmpty())
return nullptr;
// According to
// http://lists.w3.org/Archives/Public/public-html/2009Jul/0947.html,
// the "inherit", "initial" and "unset" values must be ignored.
const CSSValue* font_value =
parsed_style->GetPropertyCSSValue(CSSPropertyID::kFontSize);
if (font_value && font_value->IsCSSWideKeyword())
return nullptr;
fetched_fonts_.insert(font_string, parsed_style);
font_lru_list_.PrependOrMoveToFirst(font_string);
// Hard limit is applied here, on the fly, while the soft limit is
// applied at the end of the task.
if (fetched_fonts_.size() > HardMaxFonts()) {
DCHECK_EQ(fetched_fonts_.size(), HardMaxFonts() + 1);
DCHECK_EQ(font_lru_list_.size(), HardMaxFonts() + 1);
fetched_fonts_.erase(font_lru_list_.back());
fonts_resolved_using_default_style_.erase(font_lru_list_.back());
font_lru_list_.pop_back();
}
}
SchedulePruningIfNeeded();
return parsed_style;
}
void CanvasFontCache::DidProcessTask(const base::PendingTask& pending_task) {
DCHECK(pruning_scheduled_);
DCHECK(main_cache_purge_preventer_);
while (fetched_fonts_.size() > MaxFonts()) {
fetched_fonts_.erase(font_lru_list_.back());
fonts_resolved_using_default_style_.erase(font_lru_list_.back());
font_lru_list_.pop_back();
}
main_cache_purge_preventer_.reset();
Thread::Current()->RemoveTaskObserver(this);
pruning_scheduled_ = false;
}
void CanvasFontCache::SchedulePruningIfNeeded() {
if (pruning_scheduled_)
return;
DCHECK(!main_cache_purge_preventer_);
main_cache_purge_preventer_ = std::make_unique<FontCachePurgePreventer>();
Thread::Current()->AddTaskObserver(this);
pruning_scheduled_ = true;
}
bool CanvasFontCache::IsInCache(const String& font_string) {
return fetched_fonts_.find(font_string) != fetched_fonts_.end();
}
void CanvasFontCache::PruneAll() {
fetched_fonts_.clear();
font_lru_list_.clear();
fonts_resolved_using_default_style_.clear();
}
void CanvasFontCache::Trace(Visitor* visitor) const {
visitor->Trace(fetched_fonts_);
visitor->Trace(document_);
}
void CanvasFontCache::Dispose() {
main_cache_purge_preventer_.reset();
if (pruning_scheduled_) {
Thread::Current()->RemoveTaskObserver(this);
}
}
} // namespace blink
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