Khmer, and I'll tell you about all the text stacks

by Michael S. Kaplan, published on 2007/11/19 10:16 -05:00, original URI:

If I have to explain the title then you won't think the joke is funny anyway; if that is the case just replace Khmer with Come Here and then read on....

There was a post over on the Connect site entitled All controls in WPF Application not supporting Khmer Unicode. Summary version:

On Design Form of WPF Application, I tested with all controls like button, label, menu, listbox, listview, etc... do not support Khmer Unicode on Form Design, but Code behind on XAML supports Khmer Unicode. If I use Khmer Unicode in All controls of VB.NET Application, they well support with Khmer Unicode.

The issue should not have been resolved with a "not reproducible" tag. Since it can in fact be reproduced.... 

And it was funny that I was going to answer that question anyway, here.

Because you see, about a week ago, Masavang asked over on the OpenType list:

Dear Community users

The ProType Titler seeme working with Opentype feature ( Ligatures, Environmental Ligature ...), but my OpenType Khmer Font making with Volt ( working very well with others Applications ) don't works with Protype Titler of Sony Vegas Pro 8.
My question is : Do Opentype feature of Khmer Opentype are compatible of those of Protype Titler ? or some thing else wrong. Do some one know about these problemes ?


Developer Sergey Malkin was able to clarify what was going on here:

If understand correctly, ProType Titler is using WPF platform. Unfortunately, it does not support Khmer shaping.

It occurred to me that a conversation about the various text stacks might be in order. :-) 

There are a few different text stack on Microsoft platforms that support complex scripts.

The first one is GDI/Uniscribe, which is the basic Win32 method of doing these things. It is the most fully featured of all of the ones I am going to talk about. It even has low-level support for the many option features within OpenType, although at present the number of clients who ought to be making use of this functionality (cough... OFFICE!... cough) are not there yet.

And the second one is GDI+, which is no longer having new work done for various shaping engines -- the TextRenderer work was done so that WinForms would not be cast adrift in terms of new scripts just because GDI+ was. At present there is no support for these optional features there in this Uniscribe wrapper, and definitely none in GDI+.

And the third is Avalon, the Windows Presentation Foundation -- it has support for most but not all of the shaping engines that are also in Uniscribe, but some are missing (e.g. the one for Khmer, as Sergey indicated). It does have support for optional OpenType features, as well.

Now obviously none of these projects are put together with scotch tape and rubber bands -- they are each major projects that contain many commonalities generally not shared between them (glyph caches, font caches, shaping engines, etc.), and thankfully some of the smartest people working across the various relevant teams for these projects and for OpenType/typography/shaping engines are looking hard at making sure that performance and functionality (e.g. Masavang's and other) issues can be addressed here.

It is way too early to say whether anything actually needs to be done here (let alone what might be done!) beyond a general goal of providing feature parity for script/language in all of the places it makes sense to do so, but I'm sure that you'll hear something about it when/if there is something to say. :-)

In the meantime, I'll see what I can do about some interesting samples in this area....


This post brought to you by(U+17a1, a.k.a. KHMER LETTER LA)

# Arun Philip on 20 Nov 2007 4:51 AM:

Your post titles are scaling new heights (lows?), you rogue!

# Jeroen Ruigrok van der Werven on 20 Nov 2007 5:43 AM:


have you seen any good technical Pango/Uniscribe comparisons?

The whole area of layout engines seems to be a very niche and small place where much more people could be needed. Then again, the whole g11n domain is not that filled with people and it is such an important part for any company trying to expand outside their own country.

# John Cowan on 2 Nov 2008 3:22 PM:

That word is not pronounced how you think it's pronounced, despite a good deal of misinformation out there.  It actually rhymes with <i>Thai</i>, which really is pronounced how you think it's pronounced.  (The standard spelling in English follows an old Khmer dialect pronunciation.)

# Michael S. Kaplan on 2 Nov 2008 3:41 PM:

I don't mind if my subject line pronunciation-based puns don't work with actual pronunciations (as long as they work with the pronunciations most people use, and that the actual content provides value!).

# Michael S. Kaplan on 2 Nov 2008 6:44 PM:

Though I am having some trouble with this -- every conversation I have ever heard talking about it whether in Unicode or Microsoft or elsewhere has used "Cuh-Mare" and you are saying it would be more like "Cuh-Meyer" ?

John Cowan on 26 Nov 2010 4:46 PM:

No, I mean the final "r" is silent: Khmer rhymes with pie, exactly.

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