[FreeType] Add support for the USE_TYPO_METRICS flag

• Component: Text
• Status: RESOLVED FIXED

[Frédéric Wang (:fredw)]

This is bug 131839 for Linux.

[Frédéric Wang (:fredw)]

Created attachment 263512 [details]
Patch

[Myles C. Maxfield]

Comment on attachment 263512 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=263512&action=review

I can't comment on the FreeType-specific stuff, but this approach looks good to me.

> Source/WebCore/platform/graphics/freetype/SimpleFontDataFreeType.cpp:72
> +    if (TT_OS2* os2 = static_cast<TT_OS2*>(FT_Get_Sfnt_Table(freeTypeFace, ft_sfnt_os2))) {
> +        const FT_Short kUseTypoMetricsMask = 1 << 7;
> +        if (os2->fsSelection & kUseTypoMetricsMask) {

There's really no FreeType API for this? :(

[Frédéric Wang (:fredw)]

> There's really no FreeType API for this? :(

I checked the Cairo and FreeType online documentation and could not find any easier way to retrieve the typo values (the yscale parameter was actually taken from Gecko's gfx/thebes/gfxFT2Utils.cpp and they also hardcode the use_typo_metrics bit). I just downloaded the freetype-2.6 source and searched for "typo" metrics but I did not find anything either...

[Martin Robinson]

Comment on attachment 263512 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=263512&action=review

Looks good to me, except for a few nits.

> Source/WebCore/platform/graphics/freetype/SimpleFontDataFreeType.cpp:70
> +    if (TT_OS2* os2 = static_cast<TT_OS2*>(FT_Get_Sfnt_Table(freeTypeFace, ft_sfnt_os2))) {

I think WebKit style specifies this should be called OS2Table instead of os2.

> LayoutTests/fonts/use-typo-metrics-1.html:9
> +    src: url("./lineheight5000-typolineheight2300.woff");

Is the "./" necessary here?

[Frédéric Wang (:fredw)]

Created attachment 263619 [details]
Patch final version

Thanks!

[Frédéric Wang (:fredw)]

Created attachment 263663 [details]
Patch final version

[Frédéric Wang (:fredw)]

Committed r191378: <http://trac.webkit.org/changeset/191378>