Implement CSS font-display

third_party/WebKit/Source/core/css/RemoteFontFaceSource.cpp

 // Copyright 2014 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 "config.h"
 #include "core/css/RemoteFontFaceSource.h"
 
 #include "core/css/CSSCustomFontData.h"
 #include "core/css/CSSFontFace.h"
 #include "core/css/FontLoader.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/fonts/FontDescription.h"
 #include "platform/fonts/SimpleFontData.h"
 #include "public/platform/Platform.h"
 #include "wtf/CurrentTime.h"
 
 namespace blink {
 
-RemoteFontFaceSource::RemoteFontFaceSource(FontResource* font, PassRefPtrWillBeRawPtr<FontLoader> fontLoader)
+RemoteFontFaceSource::RemoteFontFaceSource(FontResource* font, PassRefPtrWillBeRawPtr<FontLoader> fontLoader, FontDisplay display)
     : m_font(font)
     , m_fontLoader(fontLoader)
+    , m_display(display)
+    , m_period(display == FontDisplaySwap ? SwapPeriod : BlockPeriod)
 {
     m_font->addClient(this);
 }
 
 RemoteFontFaceSource::~RemoteFontFaceSource()
 {
     m_font->removeClient(this);
     pruneTable();
 }
 
 void RemoteFontFaceSource::pruneTable()
 {
     if (m_fontDataTable.isEmpty())
         return;
 
     for (const auto& item : m_fontDataTable) {
         SimpleFontData* fontData = item.value.get();
         if (fontData && fontData->customFontData())
             fontData->customFontData()->clearFontFaceSource();
     }
     m_fontDataTable.clear();
 }
 
 bool RemoteFontFaceSource::isLoading() const
 {
-    return !m_font->stillNeedsLoad() && !m_font->isLoaded();
+    return m_period != FailurePeriod && !m_font->stillNeedsLoad() && !m_font->isLoaded();
 }
 
 bool RemoteFontFaceSource::isLoaded() const
 {
-    return m_font->isLoaded();
+    return m_period == FailurePeriod || m_font->isLoaded();

[Yoav Weiss, 2015/11/02 08:57:28]

So failure is defined as loaded? Can you add a link to the corresponding spec
definition (if there is one)?

[Kunihiko Sakamoto, 2015/11/04 02:32:51]

This is to make the RemoteFontFaceSource behave as if the load failed.

https://tabatkins.github.io/specs/css-font-display/#font-failure-period
As side effects, this turns the FontFace status [1] to "error" and fires
"loadingerror" event [2] on document.fonts. I'm not sure this is correct, so
filed a spec bug. https://github.com/tabatkins/specs/issues/48

[1] https://drafts.csswg.org/css-font-loading/#dom-fontface-status
[2] https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-loadingerror

[Kunihiko Sakamoto, 2015/11/17 05:47:43]

Changed it not to treat failure period as loaded, as per the spec bug
discussion. https://github.com/tabatkins/specs/issues/48

 }
 
 bool RemoteFontFaceSource::isValid() const
 {
-    return !m_font->errorOccurred();
+    return m_period != FailurePeriod && !m_font->errorOccurred();
 }
 
 void RemoteFontFaceSource::didStartFontLoad(FontResource*)
 {
     // We may send duplicated reports when multiple CSSFontFaceSource are
     // registered at this FontResource. Associating the same URL to different
     // font-family causes the case, but we treat them as indivisual resources.
     m_histograms.loadStarted();
 }
 
 void RemoteFontFaceSource::fontLoaded(FontResource*)
 {
     m_histograms.recordRemoteFont(m_font.get());
 
     m_font->ensureCustomFontData();
     if (m_font->status() == Resource::DecodeError)
         m_fontLoader->didFailToDecode(m_font.get());
 
     pruneTable();
     if (m_face) {
         m_fontLoader->fontFaceInvalidated();
         m_face->fontLoaded(this);
     }
 }
 
-void RemoteFontFaceSource::fontLoadWaitLimitExceeded(FontResource*)
+void RemoteFontFaceSource::fontLoadShortLimitExceeded(FontResource*)
 {
+    if (m_display == FontDisplayFallback)
+        switchToSwapPeriod();
+    else if (m_display == FontDisplayOptional)
+        switchToFailurePeriod();
+}
+
+void RemoteFontFaceSource::fontLoadLongLimitExceeded(FontResource*)
+{
+    if (m_display == FontDisplayAuto || m_display == FontDisplayBlock)
+        switchToSwapPeriod();
+    else if (m_display == FontDisplayFallback)
+        switchToFailurePeriod();
+}
+
+void RemoteFontFaceSource::switchToSwapPeriod()
+{
+    ASSERT(m_period == BlockPeriod);
+    m_period = SwapPeriod;
+
     pruneTable();
     if (m_face) {
         m_fontLoader->fontFaceInvalidated();
-        m_face->fontLoadWaitLimitExceeded(this);
+        m_face->fontDataInvalidated(this);
     }
 
     m_histograms.recordFallbackTime(m_font.get());
 }
 
+void RemoteFontFaceSource::switchToFailurePeriod()
+{
+    if (m_period == BlockPeriod)
+        switchToSwapPeriod();
+    ASSERT(m_period == SwapPeriod);
+    m_period = FailurePeriod;
+
+    pruneTable();
+    if (m_face) {
+        m_fontLoader->fontFaceInvalidated();
+        m_face->fontLoaded(this);
+    }
+}
+
 PassRefPtr<SimpleFontData> RemoteFontFaceSource::createFontData(const FontDescription& fontDescription)
 {
     if (!isLoaded())
         return createLoadingFallbackFontData(fontDescription);
 
     // Create new FontPlatformData from our CGFontRef, point size and ATSFontRef.
     if (!m_font->ensureCustomFontData())
         return nullptr;
 
     m_histograms.recordFallbackTime(m_font.get());
 
     return SimpleFontData::create(
         m_font->platformDataFromCustomData(fontDescription.effectiveFontSize(),
             fontDescription.isSyntheticBold(), fontDescription.isSyntheticItalic(),
             fontDescription.orientation()), CustomFontData::create());
 }
 
 PassRefPtr<SimpleFontData> RemoteFontFaceSource::createLoadingFallbackFontData(const FontDescription& fontDescription)
 {
     // This temporary font is not retained and should not be returned.
     FontCachePurgePreventer fontCachePurgePreventer;
     SimpleFontData* temporaryFont = FontCache::fontCache()->getNonRetainedLastResortFallbackFont(fontDescription);
     if (!temporaryFont) {
         ASSERT_NOT_REACHED();
         return nullptr;
     }
-    RefPtr<CSSCustomFontData> cssFontData = CSSCustomFontData::create(this, m_font->exceedsFontLoadWaitLimit() ? CSSCustomFontData::VisibleFallback : CSSCustomFontData::InvisibleFallback);
+    RefPtr<CSSCustomFontData> cssFontData = CSSCustomFontData::create(this, m_period == BlockPeriod ? CSSCustomFontData::InvisibleFallback : CSSCustomFontData::VisibleFallback);
     return SimpleFontData::create(temporaryFont->platformData(), cssFontData);
 }
 
 void RemoteFontFaceSource::beginLoadIfNeeded()
 {
     if (m_font->stillNeedsLoad())
         m_fontLoader->addFontToBeginLoading(m_font.get());
 
     if (m_face)
         m_face->didBeginLoad();
@@ skipping 56 matching lines @@
     if (size < 50 * 1024)
         return "WebFont.DownloadTime.1.10KBTo50KB";
     if (size < 100 * 1024)
         return "WebFont.DownloadTime.2.50KBTo100KB";
     if (size < 1024 * 1024)
         return "WebFont.DownloadTime.3.100KBTo1MB";
     return "WebFont.DownloadTime.4.Over1MB";
 }
 
 } // namespace blink