On 25 Nov 2004 at 15:52, Rich Mellor wrote:
> I am glad to see that this has at least inspired some interest and
> hopefully we will see the beginnings of some work towards an actual
> product - although we still have no confirmation that Proforms can output
> to a Windows only printer - if not, we may be in trouble. Surely someone
> has access to one of the cheap Epsons on a PC and can install QPC2 plus
> Linedesign and see if they can print something direct to that printer
> successfully. If there are no volunteers, guess I could always go and buy
> one for £40 or so just to try it.
Don't even bother. There is no Proforma driver for GDI printers, so no output
to them.
Remember, each different GDI printer needs its own driver...
> However, I have been asked to explain why the program needs to be so
> complex.
>
> I admit to the original moanings about using modern printers from within
> the QL. Wolfgang produced an excellent ASCII to Proforma filter which
> will overcome this, by taking an ASCII file and sending it to Proforma for
> printing. This is sufficient for printing plain ASCII files, and could be
> adapted to include EPSON control codes for files printed by some QL
> utilities.
Well , if one told me what these were, I'd probably have done it already...
> This however creates two problems:
>
> 1) Some programs on the QL only allow you to print to ser1 or PAR and do
> not allow you to send data to a file.
I haven't seen one of those yet, but anyway the PFF device will take care of
this, a simple buffer (or actually not even that, it'll squirt everything to
a pipe)...
> 2) It is more user friendly to have a printing process which is invisible
> to the user. If the user has to always print to a file then run another
> program to get output, they will soon get fed up of this process and
> abandon the QL altogether.
I doubt it. Sell it to them as a modern version of a printer spooler.
> Joachim then identified a third problem if we are to use a PFF device. If
> two programs on the QL try to print at the same time, then the output can
> become corrupt.
1 - Design the PFF device so that it can only have one file open to it at any
time. Trrrrrrrrrrivial,since we're designing that device anyway.
2 - What happens TODAY when two apps try to print to par/ser
at the same time? In what way is the user better/worse off, even if we don't
implement n° 1 above ?
> We therefore decided that what is needed is a printer
> management program (the FILTER THING) which will capture the output from
> all the open PFF devices and store it for processing by filters one at a
> time.
In other words, you want to create a sort of buffer which is filled in
through a device driver io routine, but is not part of that device driver.
Or perhaps I misunderstand?
> It would also enable more than one type of filter to be present in
> the QL at the same time (for example, for printing via Proforma, creating
> Postscript output or even for creating HTML output).
Of course, we are still talking about simpe ascii files being transformed
into all that, aren't we?
> This FILTER THING is the most complex part of the program, but essential
> to ensure that the user can have a wide range of printing options
> available.
A simple set of different filter progs called, if you want, from one printer
spooler selctor would be enough for that.
> A flow chart appears below of the way the system will work:
> Proforma Filter Flow-Chart
>
(...)
> FILTER THING opens a channel to the
> temporary storage (pipe or file)
> and passes the channel ID back to the
> PFF device
I'd be MOST interested in knowing how you'll handle that (see my other
message to Joachim).
> |
> |
> PFF device outputs the data to the
> specified channel ID
> |
> |
(...)
(USB)
No drivers for USB = no USB printers.
Wolfgang
NB - please bear with me if the above comments all sound (too) curt. I'm
short of time...
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