[Python-Dev] PEP 393 Summer of Code Project

[Neil Hodgson]

Guido van Rossum:

> On Wed, Aug 31, 2011 at 5:58 PM, Neil Hodgson <nyamatongwe at gmail.com> wrote:
>> [...] some text drawing engines draw decomposed characters ("o"
>> followed by " ̈" -> "ö") differently compared to their composite
>> equivalents ("ö") and this may be perceived as better or worse. I'd
>> like to offer an option to replace some decomposed characters with
>> their composite equivalent before drawing but since other characters
>> may look worse, I don't want to do a full normalization.
>
> Isn't this an issue properly solved by various normal forms?

   No, since normalization of all cases may actually lead to worse
visuals in some situations. A potential reason for drawing decomposed
characters differently is that more room may be allocated for the
generic condition where a character may be combined with a wide
variety of accents compared with combining it with a specific accent.

   Here is an example on Windows drawing composite and decomposed
forms to show the types of difference often encountered.
http://scintilla.org/Composite.png
   Now, this particular example displays both forms quite reasonably
so would not justify special processing but I have seen on other
platforms and earlier versions of Windows where the umlaut in the
decomposed form is displaced to the right even to the extent of
disappearing under the next character. In the example, the decomposed
'o' is shorter and lighter and the umlauts are round instead of
square.

   Neil