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Missing test assertion, reconstructing (searchRange, entrySelector and rangeShift).

From: Chris Lilley <chris@w3.org>
Date: Tue, 29 Nov 2011 14:49:39 +0100
Message-ID: <1802876907.20111129144939@w3.org>
To: www-font@w3.org
Hello,

I just noticed that the following conformable statement in the WOFF spec is not marked up as a testable assertion:

The sfnt header includes three fields (searchRange, entrySelector and rangeShift) that are designed to facilitate a binary search of the table directory. As the proper value for each of these fields can be computed directly from the number of font tables, they are not stored in the WOFF file. User agents that decode WOFF files back to an sfnt structure MUST therefore compute the correct values for these fields in the sfnt header, as described in the OpenType/OFF specification.[OFF]
http://dev.w3.org/webfonts/WOFF/spec/#WOFFHeader

On the one hand, this might be deliberate because the UA is not required to expose the reconstructed sfnt font and thus, its hard to test.

On the other hand, it could be testable for UAs that do expose it.

On a third hand, the assertion could be broadened to include authoring tools which perform round-trip or bidirectional conversion,and would be testable (perhaps the bitwise-identical authoring tool tests already cover this).

In any case I wanted to be sure whether this was an inadvertent omission, or was by design.

-- 
 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups
Received on Tuesday, 29 November 2011 13:49:43 UTC

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