Re: flags,beams and stem length in forced directions - output improvement

[Carl Sorensen]

On 1/22/11 5:38 PM, "Janek Warchoł" <address@hidden>
wrote:

> W dniu 22 stycznia 2011 19:06 użytkownik Carl Sorensen
> <address@hidden> napisał:
>> On 1/22/11 10:59 AM, "Janek Warchoł" <address@hidden>
>> wrote:
>>>>> Now i'm almost done. However i still don't know how to attach
>>>>> different versions of flags to the stems.
>> 
>> Look in lily/stem.cc.  Method Stem::calc_flag.
>> lines 643-662 are about where it's currently done.
> 
> I see! That's exactly what i want.
> Now i ran into another problem. I wanted to insert this
> 
>   if (flag_style == "") // i'm preparing additional flags only for
> ordinary font style
>     {
>       if (length < 6.83)
>         {
>           if (length > 6.5) font_char += "1";
>                     // flags.u31 would be a 8th flag that is only a
> bit shorter than regular 8th flag (flags.u3)
>           else if (length > 6.16) font_char += "2";
>                     // flags.u32 would be a 8th flag that is a bit
> shorter than flags.u31, and so on
>           else if (length > 5.83) font_char += "3";
>           else if (length > 5.5) font_char += "4";
>           else if (length > 5.16) font_char += "5";
>           else font_char += "6";
>         }
>     }
> 
> into line 639 of stem.cc (just before Font_metric *fm =
> Font_interface::get_default_font (me);)
> but unfortunately length variable is local to Stem::calc_length. I've
> tried defining it in the top-level, but failed.

Well, you could call calc_length to get the stem length, since you have the
stem grob in the form of me, i.e.


Real length = robust_scm2double (me->calc_length (smob));


If you want to, you could try adding a saved value for the length so you
don't have to make this call twice.

That would involve modifying lily/include/stem.hh so that you had a private
variable Real length_, and then at the end of Stem::calc_length you would do
an assignment length_ = length; (just before return scm_from_double
(length);)  

I would probably take the latter approach, since we have lots of stems in
the music and I think it would be significantly faster, but only make a
minor difference in storage space.

HTH,

Carl