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Printing dotted lines

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  Printing dotted lines Harriet Bazley <harriet@bazleyfamily.co.uk> - 2018-02-03 23:42 +0000
    Re: Printing dotted lines news@sprow.co.uk - 2018-02-03 23:55 -0800
      Re: Printing dotted lines Harriet Bazley <harriet@bazleyfamily.co.uk> - 2018-02-04 18:03 +0000
        Re: Printing dotted lines Rick Murray <Rick@bogus.email.address> - 2018-02-04 20:27 +0100
        Re: Printing dotted lines Steve Fryatt <news@stevefryatt.org.uk> - 2018-02-04 22:50 +0000
          Re: Printing dotted lines Martin Wuerthner <spamtrap@mw-software.com> - 2018-02-08 12:06 +0100
          Re: Printing dotted lines Harriet Bazley <harriet@bazleyfamily.co.uk> - 2018-02-09 01:15 +0000
            Re: Printing dotted lines Matthew Phillips <spam2011m@yahoo.co.uk> - 2018-02-09 08:20 +0000
              Re: Printing dotted lines Harriet Bazley <harriet@bazleyfamily.co.uk> - 2018-02-09 14:52 +0000

#5390 — Printing dotted lines

Trying to work out why Powerbase prints dotted lines to screen but not to
printer - I've managed the following attempted test case program.


The PLOT code in PROCdiagonal produces converging dotted and solid lines on
screen, but two converging solid lines when sent to the printer.
Are the PLOT codes in the range 16-23 not suitable for use in hard copy?

-------------------------------------------------------------------------

DIM area% 16
DIM transform% 16
DIM origin% 8
DIM draw_rectangle% 16
MODE 32
PROCdiagonal

handle%=OPENOUT("printer:")
IF handle%=0 THEN END

SYS "PDriver_SelectJob",handle%,"Dotted test"
area%!0=0:area%!4=0:area%!8=800:area%!12=800
transform%!0=(1<<16):transform%!4=0:transform%!8=0:transform%!12=(1<<16)
origin%!0=1024:origin%!4=1024

SYS "PDriver_GiveRectangle",1,area%,transform%,origin%,&FF000000
SYS "PDriver_DrawPage",1,draw_rectangle%,0,0
PROCdiagonal

SYS "PDriver_EndJob", handle%
CLOSE#handle%
END

DEF PROCdiagonal
MOVE 50,150
PLOT 5, 600, 600

MOVE 50,250
PLOT 21, 600, 600
ENDPROC


-- 
Harriet Bazley                     ==  Loyaulte me lie ==

Nothing is foolproof - to a sufficiently talented fool

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#5392

On Saturday, 3 February 2018 23:52:08 UTC, Harriet Bazley  wrote:
> Trying to work out why Powerbase prints dotted lines to screen but not to
> printer - I've managed the following attempted test case program.
>
> Are the PLOT codes in the range 16-23 not suitable for use in hard copy?

In the bit image driver there looks to be some prototype code
  https://www.riscosopen.org/viewer/view/castle/RiscOS/Sources/Printing/Modules/PDModules/s/PDriverDP/Plot?rev=4.2;content-type=text%2Fx-cvsweb-markup#l264

however nobody ever got round to writing the PostScript equivalent
  https://www.riscosopen.org/viewer/view/castle/RiscOS/Sources/Printing/Modules/PDModules/s/PDriverPS/Plot?rev=4.1.7.1;content-type=text%2Fx-cvsweb-markup#l229

and so to ensure they're both consistent, it's disabled in both
  https://www.riscosopen.org/viewer/view/castle/RiscOS/Sources/Printing/Modules/PDModules/s/Core/PDriver?rev=4.10;content-type=text%2Fx-cvsweb-markup#l105

Or, in short, no - solid lines only at the moment,
Sprow.

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#5399

On 4 Feb 2018 as I do recall,
          news@sprow.co.uk wrote:

> On Saturday, 3 February 2018 23:52:08 UTC, Harriet Bazley  wrote:
> > Trying to work out why Powerbase prints dotted lines to screen but not to
> > printer - I've managed the following attempted test case program.
> >
> > Are the PLOT codes in the range 16-23 not suitable for use in hard copy?

[snip]


> Or, in short, no - solid lines only at the moment,

Thanks - is there a recommended way of printing dotted lines?
(Surely commercial programs must do this sometimes?)

-- 
Harriet Bazley                     ==  Loyaulte me lie ==

Many are called, few are chosen.  Fewer still get to do the choosing.

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#5400

In article <3aba32c556.harriet@blueyonder.co.uk>,

> Thanks - is there a recommended way of printing dotted lines?

Probably not useful but... DrawFile? Plotting pixels manually?

-- 
  ___
 /__/ o __  /_
/ \  / /__ / \ (heyrick one nine seven three at yahoo dot co dot uk)

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#5401

On 4 Feb, Harriet Bazley wrote in message
    <3aba32c556.harriet@blueyonder.co.uk>:

> On 4 Feb 2018 as I do recall,
>           news@sprow.co.uk wrote:
> 
> > On Saturday, 3 February 2018 23:52:08 UTC, Harriet Bazley  wrote:
> > > Trying to work out why Powerbase prints dotted lines to screen but not
> > > to printer - I've managed the following attempted test case program.
> > >
> > > Are the PLOT codes in the range 16-23 not suitable for use in hard
> > > copy?
> 
> [snip]
>
> > Or, in short, no - solid lines only at the moment,
> 
> Thanks - is there a recommended way of printing dotted lines? (Surely
> commercial programs must do this sometimes?)

The Draw module (Draw_Stroke, etc).

In fact, the PRM states (p 3-564) that "you should use calls to the Draw
module to print object-oriented graphics such as rectangles. This is
preferable to using VDU and PLOT sequences."

Very possibly for exactly this reason...

-- 
Steve Fryatt - Leeds, England

http://www.stevefryatt.org.uk/

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#5403

Steve Fryatt <news@stevefryatt.org.uk> wrote:

> On 4 Feb, Harriet Bazley wrote in message
>     <3aba32c556.harriet@blueyonder.co.uk>:
> 
> > On 4 Feb 2018 as I do recall,
> >           news@sprow.co.uk wrote:
> > 
> > > On Saturday, 3 February 2018 23:52:08 UTC, Harriet Bazley  wrote:
> > > > Trying to work out why Powerbase prints dotted lines to screen but
> > > > not to printer - I've managed the following attempted test case
> > > > program.
> > > >
> > > > Are the PLOT codes in the range 16-23 not suitable for use in hard
> > > > copy?
> > 
> > [snip]
> >
> > > Or, in short, no - solid lines only at the moment,
> > 
> > Thanks - is there a recommended way of printing dotted lines? (Surely
> > commercial programs must do this sometimes?)
> 
> The Draw module (Draw_Stroke, etc).
> 
> In fact, the PRM states (p 3-564) that "you should use calls to the Draw
> module to print object-oriented graphics such as rectangles. This is
> preferable to using VDU and PLOT sequences."

In addition to this generic advice, there is detailed information about each
individual PLOT code in the table headed "Treatment of character sequences"
in the WrchV section. Not surprisingly, on p 3-583 it states for PLOT
25,16-31: "Processed: plots solid line (use Draw_Stroke to get dotted
lines)". So, this is documented behaviour, not just an accident of the
current implementation. Various PLOT codes (e.g., line fill and rectangle
copy) are even faulted.

-- 
Martin Wuerthner         MW Software      http://www.mw-software.com/

------- RISC OS Software for Design, Printing and Publishing --------

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#5404

On 4 Feb 2018 as I do recall,
          Steve Fryatt  wrote:

> On 4 Feb, Harriet Bazley wrote in message
>     <3aba32c556.harriet@blueyonder.co.uk>:
>
> > On 4 Feb 2018 as I do recall,
> >           news@sprow.co.uk wrote:
> >
> > > On Saturday, 3 February 2018 23:52:08 UTC, Harriet Bazley  wrote:
> > > > Trying to work out why Powerbase prints dotted lines to screen but not
> > > > to printer - I've managed the following attempted test case program.
> > > >
> > > > Are the PLOT codes in the range 16-23 not suitable for use in hard
> > > > copy?
> >
> > [snip]
> >
> > > Or, in short, no - solid lines only at the moment,
> >
> > Thanks - is there a recommended way of printing dotted lines? (Surely
> > commercial programs must do this sometimes?)
>
> The Draw module (Draw_Stroke, etc).

Substituting the following code

DEF PROChrule(x%,y%,plot%)
SYS "Wimp_SetColour",rulewimpcol%
MOVE x%,y%
CASE plot% OF
  WHEN 1:PLOT plot%,LenLineP%,0
  WHEN 17:
  draw%!200=0:REM offset of first dash
  draw%!204=1:REM number of on/off elements in pattern
  draw%!208=70:REM length of first (and only) element
  REM set up draw path block
  !draw%=2:REM Start of path, i.e. move to x,y
  draw%!4=x%*256:REM draw units are 1/256 of OS units
  draw%!8=y%*256
  draw%!12=8:REM Draw line
  draw%!16=draw%!4+(LenLineP%*256):REM absolute x value
  draw%!20=draw%!8:REM no change in y
  draw%!24=0: REM end of path
  SYS "Draw_Stroke",draw%,0,0,0,0,0,draw%+200
ENDCASE
ENDPROC

for the PLOT 17 commands produces what looks like dashed lines on the
screen, but what looks like solid lines when printing to paper/PDF.   Redraw
on the PDF is also *incredibly* slow (as is screen redraw under emulation on
Windows, apparently).   If I zoom right in on the PDF I get what looks like
incredibly fine dots giving the impression of a solid line.

What is a sensible set of values for the 'dash pattern' block in order to
give the impression of a dotted line, and would it help if I could get
Draw_Stroke to produce something other than the default 'thin' line?
(Apparently you need to set up start and end cap information to alter the
line thickness....)



-- 
Harriet Bazley                     ==  Loyaulte me lie ==

Do not underestimate the power of the Force.

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#5405

In message <cc9769c756.harriet@blueyonder.co.uk>
 on 9 Feb 2018 Harriet Bazley  wrote:

> On 4 Feb 2018 as I do recall,
>           Steve Fryatt  wrote:
> 
> > On 4 Feb, Harriet Bazley wrote in message
> >     <3aba32c556.harriet@blueyonder.co.uk>:
> >
> > > On 4 Feb 2018 as I do recall,
> > >           news@sprow.co.uk wrote:
> > >
> > > > On Saturday, 3 February 2018 23:52:08 UTC, Harriet Bazley  wrote:
> > > > > Trying to work out why Powerbase prints dotted lines to screen but
> > > > > not to printer - I've managed the following attempted test case
> > > > > program.
> > > > >
> > > > > Are the PLOT codes in the range 16-23 not suitable for use in hard
> > > > > copy?
> > >
> > > [snip]
> > >
> > > > Or, in short, no - solid lines only at the moment,
> > >
> > > Thanks - is there a recommended way of printing dotted lines? (Surely
> > > commercial programs must do this sometimes?)
> >
> > The Draw module (Draw_Stroke, etc).
> 
> Substituting the following code
> 
> DEF PROChrule(x%,y%,plot%)
> SYS "Wimp_SetColour",rulewimpcol%
> MOVE x%,y%
> CASE plot% OF
>   WHEN 1:PLOT plot%,LenLineP%,0
>   WHEN 17:
>   draw%!200=0:REM offset of first dash
>   draw%!204=1:REM number of on/off elements in pattern
>   draw%!208=70:REM length of first (and only) element
>   REM set up draw path block
>   !draw%=2:REM Start of path, i.e. move to x,y
>   draw%!4=x%*256:REM draw units are 1/256 of OS units
>   draw%!8=y%*256
>   draw%!12=8:REM Draw line
>   draw%!16=draw%!4+(LenLineP%*256):REM absolute x value
>   draw%!20=draw%!8:REM no change in y
>   draw%!24=0: REM end of path
>   SYS "Draw_Stroke",draw%,0,0,0,0,0,draw%+200
> ENDCASE
> ENDPROC
> 
> for the PLOT 17 commands produces what looks like dashed lines on the
> screen, but what looks like solid lines when printing to paper/PDF.  
> Redraw on the PDF is also *incredibly* slow (as is screen redraw under
> emulation on Windows, apparently).   If I zoom right in on the PDF I get
> what looks like incredibly fine dots giving the impression of a solid line.
> 
> What is a sensible set of values for the 'dash pattern' block in order to
> give the impression of a dotted line, and would it help if I could get
> Draw_Stroke to produce something other than the default 'thin' line?
> (Apparently you need to set up start and end cap information to alter the
> line thickness....)

Thin lines can cause a few issues. It's not that hard to set up start and end
cap information. If you choose a bevelled or rounded join style, rather than
mitred, then all the rest of the bytes in the join/cap block can be zero,
giving you butt ends to the lines and no faffing about with mitre limits and
so on. The StrongHelp manual says that if mitres and triangles are not used,
the block need only be 4 bytes long.

The start and end caps apply to each section of a dashed line (RiscOSM makes
use of this for arrows along one-way streets) so if you set up the block as
follows you would have rounded start/end to everything:

draw%?100=1:REM rounded joins
draw%?101=1:REM rounded start
draw%?102=1:REM rounded end
draw%?103=0:REM reserved

If you want a dotted line, try this dash block:

draw%!200=0
draw%!204=2
draw%!208=&200:REM Makes a fairly small blob - adjust in tandem with width
draw%!212=&1000:REM distance between blobs - adjust as you wish

A line width of &500 corresponds to a setting of 2 in Draw's line width
styles.

Hope that helps!

-- 
Matthew Phillips
Durham

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#5406

On 9 Feb 2018 as I do recall,
          Matthew Phillips  wrote:

[snip]

> The start and end caps apply to each section of a dashed line (RiscOSM makes
> use of this for arrows along one-way streets) so if you set up the block as
> follows you would have rounded start/end to everything:
>
> draw%?100=1:REM rounded joins
> draw%?101=1:REM rounded start
> draw%?102=1:REM rounded end
> draw%?103=0:REM reserved
>
> If you want a dotted line, try this dash block:
>
> draw%!200=0
> draw%!204=2
> draw%!208=&200:REM Makes a fairly small blob - adjust in tandem with width
> draw%!212=&1000:REM distance between blobs - adjust as you wish
>
> A line width of &500 corresponds to a setting of 2 in Draw's line width
> styles.


Thanks, that helps a lot.   The values I was using were far too small!

-- 
Harriet Bazley                     ==  Loyaulte me lie ==

St George for England - St Pancras for Scotland

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