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Sections 3.1 and 5.1

From: Andrew Main <andrew.main1@ntlworld.com>
Date: Sat, 20 Aug 2005 13:20:50 +0100
To: <public-svg-print@w3.org>
Message-ID: <000001c5a581$9b6048f0$707b6c51@ez1>
1 USE CASE: Whole-Page Diagrams (WPDs) Intended for Printing (eg
Engineering Drawings)
1.1    <page> width and height
1.1.1    Use of <svg> element width and height for Printing Considered a
The <svg width=  height=> viewPort can not cover both monitor display
and paper size in a single svg file (and it would be a mistake to force
users to produce two svg files for one WPD): if I want to view a WPD, I
use "100%", "100%" to ensure maximum viewability: but each of my WPDs
has its own target paper size.  Display and printing have different
needs and the svg element as currently specified can not satisfy both
needs simultaneously.  
An alternative solution would be to insist that each WPD must have two
svg files, but that has obvious problems and is really undesirable.
1.1.2    Proposal that <svg width= height= > is used as a Display
viewPort  and <page width= height= > is used as a Printing viewPort
Given the above, it makes sense to use the <svg width= height= > for
display, and to offer <page width= height= > for printing.  It provides
an effective and natural solution to the problem.
1.2    Scaling v Clipping
5.1.1 para 2 states "In the absence of paper large enough to accomodate
the specified image size, the SVG Print device will choose the largest
available paper size and clip the image to fit within the available
area.".  I can not think of a single circumstance where that would be
satisfactory/useful/valuable for printing a WPD.  Two alternatives
suggest themselves.
1st alternative: the WPD could be scaled to fit the paper.  That
produces the whole WPD, albeit at a smaller scale than intended.  <page
width= height= > are thus treated as a preference, or suggestion, not an
absolute specification.  This is the better alternative.  
2nd alternative: the WPD could be produced on n sheets of paper (for an
A2 WPD on an A4 printer, n is 4).  This would not necessarily help, and
there would likely be drawing loss because of margins on many printers.
1.3     Restriction to a single size of paper
This may seem a non-comment, but I just wanted to say that I don't think
the Working Group should agonise over this one, because it probably will
not be a big issue either way.
An engineering project typically has more than one paper size in its
drawing set. But they are likely produced by different software, hence
separate svg files.  The restriction it is likely to go sometime in the
future (most do go in the end).  So if people are worried by it, perhaps
it could be made optional.
1.4    Two other points
1.4.1    <page> x and y not needed for WPDs...
It is in the nature of WPDs that each one must be complete when printed
out.  It is vital that nothing is lost because of either a) clipping, or
b) printer margins.  WPD svg is naturally defined with an in-built
margin: draughts-people have always left around a half-inch (12mm)
margin to allow for damage to the edges of the paper in use, eg in an
engineering workshop.  Hence 
1. The x or y in the <page> element would not be used
2. The <page> width and height, would be used and would be identical to
the paper size.
1.4.2    ...But <page> x and y worth keeping for other use cases
The <page> element x and y have value for other use cases, to allow a
margin to be achieved where the graphic does not naturally have one.
I hope that this is helpful.  And that's it from a
Andrew Main
Received on Saturday, 20 August 2005 13:12:09 UTC

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