Bug 79021 – Web font is not used in rendering for the first load

• Status: RESOLVED
• Resolution: CONFIGURATION CHANGED
• Component: CSS

[Yuzo Fujishima]

The example in https://developers.google.com/webfonts/docs/webfont_loader#Example doesn't work as expected for
- WebKit r108205 + Safari 5.1.2 on OS X 10.6.8
- Chrome 19.0.1041.0 dev on OS X 10.6.8
That is, the text is rendered in the web fonts only if the page is reloaded.

Safari Version 5.1.2 (6534.52.7), Firefox 10.0.2, and Opera 11.61 work as expected.

Reproduction steps:

1. Clear the browse cache (Option+Command+E for Safari).
2. Open the attached webfontloader.html.
3. Observe that the text is rendered in local font.
4. Reload webfontloader.html.
5. Observe that the text is rendered in Web fonts.


I observed the following:

For the fist load, CSSFontSelector::getFontData is called *before* CSSFontSelector::addFontFaceRule.
For the second load, getFontData is called *after* addFontFaceRule.

HTMLLinkElement::setCSSStyleSheet is called from
CachedCSSStyleSheet::checkNotify for the first load, while from
CachedCSSStyleSheet::didAddClient for the second load.

I guess layout should be done after the stylesheet is loaded?

(This is likely related to http://code.google.com/p/chromium/issues/detail?id=114928 )

[Yuzo Fujishima]

Created attachment 127789 [details]
Test case webfontloader.html

[Yuzo Fujishima]

Created attachment 127790 [details]
Rendering of the first load

[Yuzo Fujishima]

Created attachment 127792 [details]
Rendering of the second load

[Yuzo Fujishima]

This can be related to http://wkb.ug/79186

[Yuzo Fujishima]

Hi Antti,

Can you take a look?

I confirmed that r104060 shows this issue
    http://trac.webkit.org/changeset/104060/  Analyze stylesheet scope to minimize style recalcs
while r104052 doesn't.

[Yuzo Fujishima]

I've confirmed that applying the following patch fixes the issue. 
Document::analyzeStylesheetChange(...) is likely to have a bug.

diff --git a/Source/WebCore/dom/Document.cpp b/Source/WebCore/dom/Document.cpp
index 5125bbb..ac2b283 100644
--- a/Source/WebCore/dom/Document.cpp
+++ b/Source/WebCore/dom/Document.cpp
@@ -3273,7 +3273,6 @@ void Document::analyzeStylesheetChange(StyleSelectorUpdateFlag updateFlag, const
         if (m_styleSheets->item(i) != newStylesheets[i])
             return;
     }
-    requiresStyleSelectorReset = false;
 
     // If we are already parsing the body and so may have significant amount of elements, put some effort into trying to avoid style recalcs.
     if (!body() || m_hasNodesWithPlaceholderStyle)

[Brent Fulgham]

It looks like all browsers engines (WebKit, Blink, and Gecko) handle this load the same way -- all three "pop in" with the new font after it finishes loading.

I think this is correct behavior to avoid sites being unable to load if a web font is unavailable.

One difference from 2012, is that the web view repaints after the font finishes loading (i.e., no reload is needed by the user).

I think this behaves correctly now.

[Radar WebKit Bug Importer]

<rdar://problem/96918084>