Text laid out with the SVG -> OTF font converter does not have the same metrics as with the SVG font code path

• Component: New Bugs
• Status: RESOLVED FIXED

[Myles C. Maxfield]

Text laid out with the SVG -> OTF font converter does not have the same metrics as with the SVG font code path

[Myles C. Maxfield]

Created attachment 238287 [details]
Patch

[Darin Adler]

Comment on attachment 238287 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=238287&action=review

> Source/WebCore/svg/SVGToOTFFontConversion.cpp:221
> +    // If the font parser sees an ascent or descent of 0, it thinks that something
> +    // bad happened and takes a different path. We want it to believe us.
> +    if (!ascent)
> +        ascent = 1;
> +    if (!descent)
> +        descent = 1;

Nothing in this comment makes it clear why “1” is a suitable value to use instead of 0. Also “want it to believe us” is a vague comment. It would be more useful to say something brief and clear about how specifying a 1 FUnit value gives us the behavior we want.

> Source/WebCore/svg/SVGToOTFFontConversion.cpp:226
> +    // WebKit's SVG codepath hardcodes the line gap to be 1/10th of the font size (see SVGFontData.cpp). We should match that.

This comment is missing the “why”. Why should we match that?

> Source/WebCore/svg/SVGToOTFFontConversion.cpp:683
> +    if (!advanceAttribute.isEmpty()) {

Why the special case for the empty string? The code would do the right thing without a special case and I’d like this code better without a local variable for advanceAttribute.

> Source/WebCore/svg/SVGToOTFFontConversion.cpp:702
>              auto& advanceAttribute = glyph.fastGetAttribute(SVGNames::horiz_adv_xAttr);

This code has the same issues as the copied/pasted version of it that I commented on above.

[Myles C. Maxfield]

Comment on attachment 238287 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=238287&action=review

>> Source/WebCore/svg/SVGToOTFFontConversion.cpp:221
>> +        descent = 1;
> 
> Nothing in this comment makes it clear why “1” is a suitable value to use instead of 0. Also “want it to believe us” is a vague comment. It would be more useful to say something brief and clear about how specifying a 1 FUnit value gives us the behavior we want.

Done.

>> Source/WebCore/svg/SVGToOTFFontConversion.cpp:226
>> +    // WebKit's SVG codepath hardcodes the line gap to be 1/10th of the font size (see SVGFontData.cpp). We should match that.
> 
> This comment is missing the “why”. Why should we match that?

Done.

>> Source/WebCore/svg/SVGToOTFFontConversion.cpp:683
>> +    if (!advanceAttribute.isEmpty()) {
> 
> Why the special case for the empty string? The code would do the right thing without a special case and I’d like this code better without a local variable for advanceAttribute.

Done.

>> Source/WebCore/svg/SVGToOTFFontConversion.cpp:702
>>              auto& advanceAttribute = glyph.fastGetAttribute(SVGNames::horiz_adv_xAttr);
> 
> This code has the same issues as the copied/pasted version of it that I commented on above.

Done.

[Myles C. Maxfield]

http://trac.webkit.org/changeset/173739