Re: Guidelines for bounding boxes?

[Werner LEMBERG]

> So, if I am understanding correctly, LilyPond currently uses the
> same dimensions for both the "metrics" box and the "bounding" box
> for each glyph.  This is why the longa glyph, for example, is
> cropped in the EPS/PNG output.  Is this true?

I think so.  On the other hand, we need an exact bbox only for cropped
images, right?  ghostscript has a special output device called `bbox'
which computes a precise bounding box for its input.  Wouldn't it be
thus sufficient to introduce an intermediate step during the EPS->PNG
conversion to simply call this device?

>> Another improvement would be to provide `shaped metrics': Currently,
>> the metrics for a glyph consist of a single rectangle.  This could be
>> extended to a list of rectangles which are then merged.
> 
> But would this help with collision handling?  I was under the
> impression that the Stencil extents (which form a box) are used for
> collision handling (skylines, etc.).

My idea is that a single grob can consist of multiple boxes, providing
a more accurate skyline.  For objects taken from the emmentaler font
you only get a single rectangle currently, which is often only a very
rough approximation of the real shape.

> Or is the glyph metrics information used instead of the Stencil
> extents?

I don't know these details.


    Werner