Re: Design flaw in Rest_collision

[David Kastrup]

"address@hidden" <address@hidden> writes:

> On 5 nov. 2012, at 09:26, David Kastrup <address@hidden> wrote:
>
>> "address@hidden" <address@hidden> writes:
>> 
>>> On 5 nov. 2012, at 09:19, David Kastrup <address@hidden> wrote:
>>> 
>>>> "address@hidden" <address@hidden> writes:
>>>> 
>>>>> On 5 nov. 2012, at 06:51, address@hidden wrote:
>>>>> 
>>>>>> 1) rest->extent (common, Y_AXIS)
>>>>>> 2) Rest::height
>>>>>> 3) Rest::generic_extent_callback
>>>>>> 4) Rest::brew_internal_stencil
>>>>>> 5) Rest::glyph_name
>>>>>> 6) Staff_symbol_referencer::get_position
>>>>>> 7) rest->relative_coordinate (common, Y_AXIS);
>>>>>> 8) Rest_collision::force_shift_callback_rest
>>>>>> 9) Rest_collision::calc_positioning_done
>>>>>> 10) rest->extent (common, Y_AXIS)
>>>>> 
>>>>> A better way to describe it just to wrap heads around it, with the
>>>>> circular dependency underlined:
>>>>> 
>>>>> Rest extents depend on their stencil.  This stencil depends on
>>>>> placement on/off the staff.  Placement may depend on the placement of
>>>>> other rests.  To calculate the placement of other rests, we need to
>>>>> shift all of them.  The amount of space one must shift depends on the
>>>>> extent of the rest.
>>>> 
>>>> The co-dependent shifts should likely be done by Note_column.  About the
>>>> rest dimensions used for that: I'd likely just pick the on-staff glyph,
>>>> as the off-staff glyphs just differ by ledger lines IIRC.
>>>> 
>>>> Keep in mind that this advice is not based on any actual knowledge about
>>>> the backend, so it is entirely possible that it is a bunch of nonsense.
>>>> 
>>> 
>>> We're on the same wavelength - this is how rest pure height is
>>> calculated.  That's what I've done for now in the code I'm working on
>>> to be able to keep working.  It's ugly, tho, as it requires an
>>> exception for rests (rest ? use pure height : use height).
>> 
>> Would the problem not be the same with notes? They depend on things like
>> beam scoring, and also have the ledger line situation.
>
> The placement of notes does not depend on beam scoring.  As for ledger
> lines, ledger lines for notes are always a spanner and never built
> into the glyph.  Their width is not taken into account in any
> horizontal spacing equations unless approximations are done (see, for
> example, Note_head::include_ledger_line_height).

Do the different rest glyphs actually have different height?  Would it
be possible to stipulate that they are not supposed to, and just let the
code for rest height in general return the height of the standard rest
glyph without bothering to check the on-staffiness?

-- 
David Kastrup