[MEI-L] page sizes

[Craig Sapp]

Hi Everyone,

Here is a preliminary draft of notes I have been taking during a detailed
study of how SCORE places staff lines on the page.  This analysis is
related to the thread topic (and hopefully the attachment passes unscathed
through the list system).

Score positioning data can be used to address an exact physical location on
the page.  In SCORE there is a complex interaction between physical and
non-physical units which are designed to maximize flexibility in editing
music notation (as opposed to describing physical layout of a pre-existing
graphical image of notation).  When working with music inside of the SCORE
editor, physical units are not consciously dealt with.  The physical units
are defined at the last minute when printing to EPS files.  But basically
it is just a scaling factor which converts the SCORE data into physical
units.

I don't go into the placement objects other than staves.  For other
objects, they all must first be attached to a particular staff.  The staff
number forms part of the vertical placement of all objects on the page.  To
place a note somewhere on the page, you must first place it on a staff, and
then you add an additional vertical offset relative to the staff.  So to
calculate where a note is positioned vertically on a page you need to know
several things sorted from local to global positioning information:
(1) vertical offset of the note on the staff in terms of diatonic steps
from the staff origin (3 = bottom line of standard staff).
(2) vertical offset of the staff from its default position
(3) scaling of the staff (staff size)
(4) bottom margin of the page (offset from default staff positions)
(5) scaling of the page (excluding margins)

One important concept of SCORE placement is that the physical page size is
actually irrelevant when printing SCORE data to an EPS file.  In other
words, there is no concept of a top or right margin, and everything is
ultimately referenced to the bottom left corner as the origin of the
coordinate system for the page.

I'll look at Johannes email in more detail and maybe comment later, but the
attached study involves how to convert SCORE's internal positioning
information onto a physical page.  My intention is to go directly from
SCORE to a TIFF image directly (or directly to SCREEN from Andrew's point
of view), and get a pixel-identical image as if it were first converted to
Postscript in SCORE then to TIFF via GhostScript.

I am the primary target audience for the description at the moment, but if
someone actually reads it and needs clarification, that would be great to
add to the documentation.


-=+Craig
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