[Sugar-devel] Print Support proposal (need input) Beta

Benjamin M. Schwartz bmschwar at fas.harvard.edu
Thu Mar 19 13:42:03 EDT 2009


Vamsi Krishna Davuluri wrote:
> So in a classroom environment, can I assume the classroom server will be
> acting as the server?

You cannot assume; you have to decide what to require.

Specifically, there are at least 3 different use cases you may choose to
support:

1. USB printer connected directly to the Sugar machine.

2. Networked printer, no server. Sugar prints directly over the network.

3. All printing passes through a server.
   a. networked printer with restricted access
   b. USB printer connected directly the server
      and also
   1. the server may print every submission immediately
   2. apply automatic quotas, or
   3. require manual approval

None of these use cases is currently supported.  You will have to figure
out which ones you want to support.

I agree with Carol that #3 is the one most likely to be useful in large
school deployments.  Conversely, #1 is the one for which OLPC has had the
most requests, from adults who bought XOs during the Give 1 Get 1 program.

I think you should focus on #3 and ignore #1 and #2.  I say this because
#3 does not require CUPS, or _any_ printing stuff, in Sugar.  You don't
even need to include the "print to PDF" functionality in Sugar.  All you
need to do is send the file you want to print to the server, over the
network.  The server (running CUPS) can take the file (png for Paint, jpg
for Record, odt for Write) and convert it to postscript for printing.

I see two main virtues to this approach: it is easy to implement (so it is
likely to work), and it minimizes the amount of software running in Sugar.
 Sugar is tightly constrained in memory and disk space, so it is always
best to achieve your goals with as little code as possible.

What I am suggesting is a very minimal approach to printing.  For example,
there is no way for users to choose to print a single page from a
document, portrait vs. landscape, DPI, grayscale vs. color, double-sided,
Tray 3 or Tray 4... but that's OK.  Sugar is designed to be simple to use,
even for users who cannot yet read.  Once we have basic printing of whole
documents, then we can begin to add these kinds of advanced options.

--Ben

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