On 25 Nov 2004 at 18:46, Rich Mellor wrote: > > If Proforma cannot output to these printers - is there much point in > persuing this further as people will still be struggling to find printers > which are compatible with the QL... I disagree (again...).
I'd never buy a GDI printer, and there are many others that wouldn't (just think of Linux). There are so many pronters out there that have some kind of emulation( Laserjet, PCL etc...) . > > Well , if one told me what these were, I'd probably have done it > > already... > > Have a look at the standard Quill output for starters - Dilwyn will have a > copy of the complete Epson ESC/P programming manual somewhere for > download, but it is large. Text87 output is a lot more troublesome as it > uses a large number of text formatting commands. No, let's keep things simple: what codes are used for bold on/off, underline, high, low? > Yes it will... :-) However as you rightly say, the PFF device cannot open > a directory device if the user wants to use a hard disk for temporary > storage rather than space in memory... If he wants that, let him print to a file. > > Not really a modern version of a printer spooler if they have to (a) Print > from their program (b) remember to call up the printer spooler program to > actually see any output.. !! It is all too easy to see no output from the > printer and straight away think - oops have I run out of paper / ink.... > Or just completely forget to print out the files (eg. if you go away from > the QL while it is doing a series of reports). a) above seems pretty logical to me... If they forget that, there'll be no print. > > 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. > > Isn't that just adding to the annoyance factor - "Cannot print now cos > something else is spooling..." "Can't print now 'cause something I'm already printing something else" sounds quite logical to me. > > 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 ? > > Because it prevents the user getting annoyed by having to wait until one > print task is finished - ...which is what they have to do today... > they may not even know when it has finished and > just have to keep on trying until the PFF device lets them (if printer in > a different room, or filter is sending output to a postscript or HTML file > rather than a physical printer). > Isn't that really totally hypothetical? What if this punter wants to print 1000 files at the same time to 1000 different printers hanging off a super USB interface, some of which use Epson emulation, some others Postscript, yet others GDI and whatnot? Do we care if he can't do that? (...) > Yes that is basically it. Ooops. (...) > > ASCII or files containing epson control codes - depends on the filters > that are written for it really. Ok, same problem. > What happens when someone wants to send a graphics dump? Just add a > graphics filter. "Just" add a graphics filter. I'll let this stand as is. > > >> 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. > > Yes it would - but the problem is how the PFF device and the filters > communicate with the printer spooler. My understanding is that a THING is > much better for this purpose. The best way I've found right now is to use pipes. The PFF device just puts everything into a pipe. Then we have a standard format that anything, filters, spoolers etc... can easily get at. > > >> 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). > > See other response - suggest the FILTER THING opens a channel in readiness > if this will be a problem. How many files are you going to keep open, since your hypothetical punter will want to print so many things at once? Wolfgang ---------------------------------------- www.scp-paulet-lenerz.com _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
