Re: calculating text length

[Tapani Pälli <tapani palli nokia com>]

ext Owen Taylor wrote:
> On Wed, 2007-04-18 at 10:43 +0300, Tapani P�i wrote:
>   
>> Hello,
>>
>> I have a performance problem with Matchbox window manager calculating
>> window title width rather slowly with Pango when doing ellipsation for
>> the title. The current algorithm is rather poor but produces good result
>> and works nicely for short titles, however when our browser puts the
>> title of a webpage as window title and webpage titles seem to sometimes
>> be even 300 characters long ...
>>
>> Current algorithm takes the title, goes from title's end to begin and
>> inserts '...\0' to end and check if it would fit now. Result is always
>> perfect. However it calls several Pango funcs when checking the width
>> and besides of the algorithm I'd like to optimize width check aswell. It
>> calls pango_itemize() and then pango_shape, pango_glyph_string_extents
>> for each resulted item (word?) just like when rendering text. I thought
>> one way would be to take 'average char width' and then calculate some
>> pessimistic result out of that (?) I'd like to know if there's a quick
>> way to have extents for all characters in a string or maybe some other
>> way to quickly check how many characters of $string would fit in $w pixels.
>>     
>
> Can't you just use the ellipsization feature of Pango? That's going to
> be considerably faster than the algorithm you describe.
>
>   

I guess this is only with pango-layout? I think Matchbox is not using
layout because the rendering is slower than with just doing it in a loop
with pango-glyph-string, window title is single line always.

> 						- Owen
>   

// Tapani