[HarfBuzz] Quick show of hands needed

[Shriramana Sharma]

On 07/21/2011 09:04 AM, Pravin Satpute wrote:
> On Thursday 21 July 2011 08:51 AM, Behdad Esfahbod wrote:
>> I'm wondering: should harfbuzz try compatibility
>> composition/decomposition
>> (NFKC/NFKD) if a font doesn't support a character?
>>
>> It's easy to do so, but I'm sure how desirable that is.
>
> 1) In pango we have faced problem of backspace due to decomposition.
> i.e. U+0958  was getting decomposed into U+0915 and U+093C, so for
> entered character was required 2 backspaces to delete.

That doesn't sound right. The backspace should erase the last character 
that was input. Rendering engines should only take care of rendering 
whatever sequence of characters has been input and not change the 
sequence of characters right?

I believe what Behdad means is:

for decomposition: if HB is faced with the task of rendering U+0958 but 
the font doesn't provide that glyph, then should HB try to decompose it 
to U+0915 and U+093C and render the sequence?

for composition: (I'm not too sure about *this* one but) if HB has to 
render a decomposed sequence which has an equivalent precomposed 
character, should HB try to lookup the glyph for that precomposed 
character (as it may give proper placement of diacritic etc)?

I vote YES on both accounts. The former would be useful to present a 
meaningful rendering to the user and the latter would be useful for 
typographical finesse.

-- 
Shriramana Sharma