[webkit-dev] Platform API for Uniscribe/ComplexTextController?

[Dan Bernstein]

On Nov 29, 2009, at 10:27 AM, Kevin Ollivier wrote:

> Hi all,
> 
> The wx port is starting to look at getting proper support for complex text, and one of the first places I started looking at was the Win and Mac port implementations. I noticed that the complex text code in FontWin.cpp and FontComplexTextMac.cpp is largely the same, passing the heavy lifting down to their respective complex text controllers, and I actually wondered if they could be merged if there were some tweaks to the APIs to make them compatible.
> 
> That led me to wonder if we couldn't make ComplexTextController one of our platform classes and have USE() defines to determine the implementation. Then we could move the drawComplexText, floatWidthForComplexText, and offsetForPositionForComplexText into Font.cpp guarded by that USE() define. The wx port can provide the native font handles the Win/Mac controllers need, so it'd really be great if we could just add these into our build to get complex text support working without having to implement the complex text methods differently for each platform. 
> 
> BTW, I actually already did get UniscribeController compiling, actually, but on Windows I had to have the build script copy it to platform/graphics/wx because MSVC implicitly puts the current directory first on the path, which was causing it to pick up platform/graphics/win/FontPlatformData.h instead of the wx one when compiling that file. :( So that's something else that would need to be addressed if ports can start sharing these files.
> 
> Thanks,
> 
> Kevin

Hi Kevin,

This sounds like a generally good idea. ComplextTextController is already using USE() macros to select between Core Text and ATSUI. I am not entirely sure how the the *ComplexText() methods will be guarded in Font.cpp in your proposal. Are you suggesting something like
#if USE(ATSUI) || USE(CORE_TEXT) || USE(UNISCRIBE) || …
?

There are still some differences in behavior between ComplexTextController and UniscribeController, so you’d need to find a way to accommodate them or eliminate them.

I look forward to seeing a patch!