precision of Draw dimensions - 3 place

users
#1

All,

I want to locate a line 1/8-inch (0.125") from the margin. LOD
truncates that to 0.13". Is there a way to get 3-places?

Thanks,
Dave

#2

Is that LOD as distinct from LOW, LOC, LOI, LOB, etc.?

o Go to Tools | Options... | LibreOffice Draw | General | Scale.
o Set "Drawing scale" to 1:10.
o Locate your line at 1.25".

I trust this helps.

Brian Barker

#3

>I want to locate a line 1/8-inch (0.125") from the margin. LOD
>truncates that to 0.13". Is there a way to get 3-places?

Is that LOD as distinct from LOW, LOC, LOI, LOB, etc.?

o Go to Tools | Options... | LibreOffice Draw | General | Scale.
o Set "Drawing scale" to 1:10.
o Locate your line at 1.25".

I trust this helps.

Nope. The line is set to 0.13" from the margin.

Dave,

#4

Hi Dave,

I want to locate a line 1/8-inch (0.125") from the margin. LOD
truncates that to 0.13". Is there a way to get 3-places?

What precision do you have under the Tools - Options - Draw - Grid
dialog preferences ?

Also check out the Capture to Grid preferences, as by default, Capture
to Margins is ticked, with a default 5 pixel capture range.

Playing with these options might be the way around the problem.

Alex

#5

Looks like this is a long-standing unfixed issue:

https://forum.openoffice.org/en/forum/viewtopic.php?f=11&t=9688
(from 2008)

If you work in mm, the 2 decimal places the GUI so unreasonably forces will give a precision of 10μm. Not altogether convenient for the "traditionally minded" among us though :slight_smile:

#6

How can you know that? With the scale set to 1:10, the position shows as 1.25", not 0.13" or anything like it. Where are you getting that figure from?

With the display zoom set to 200%, if I change the position from 1.25" to 1.34" (both of which round to 0.13" at a scale of 1:1), the line jumps visibly when I click OK. That contradicts what you suggest: the two values produce different line positions.

I think the ball's in your court: can you tell us, please, what you are doing to make the behaviour different for you? ("Nope" doesn't quite cut it.)

Brian Barker

#7

Thanks all. If I make a suggestion to LO - add some more CAD abilities
to Draw such as higher precision. LOD is a very useful program, and
could be even more useful.

Dave,

#8

Agreed.

The problem's all in the GUI - the generated xml seems able to use arbitrary precision - so should be easily enough fixable.

The truly galling thing (to me) is that someone, somewhen, made a concious decision /and put effort into the code/ to do the rounding. Unwarranted work with an unwanted result. No doubt the same one who also provided the option of units of miles or km, and "Lines" - whatever they are.

#9

dave boland wrote

If I make a suggestion to LO - add some more CAD abilities
to Draw such as higher precision. LOD is a very useful program, and
could be even more useful.

Maybe request for user selectable precision? In your example 1/8 inch =
0.3175 cm so if someone uses the metric system it would require 4 decimal
cases to achieve the _exact_ same position.

If you would like to make that suggestion official, you can add it to the
Bugzilla tracker with severity=enhancement

https://bugs.documentfoundation.org/enter_bug.cgi?product=LibreOffice

This way it may be included in a future version...

#10

Math conversion function that carries 4 zeros to the right.

fraction
  decimal mm
1/64 0.0156 0.3969

That's close enough to cover most drawings.

But it would be nice to be able to set a default.

#11

This is a always what happens to good software, be it FOSS, commercial, shareware, whatever. Developers keep adding features until it becomes bloated, buggy, and slow.

Then users complain about it being bloated, buggy, and slow.

If you need that type of precision for your project, maybe LO isn't the correct software.

My suggestion would be to try page layout software and a basic CAD/drawing program. Do your drawing (I'm assuming you need to do more than just a line) then input the drawing into the page layout software where you'll have so much better options for layout than you ever will in LO.

FWIW, I've yet to see any word processing that has more than 2 decimal places for spacing.

Also, if you want truly good looking text, use page layout software and a quality font. I've yet to see a word processor that does kerning. Word processors do character spacing, which is not the same. Document processors do kerning, AFAIK.

#12

No, the all measurements in the StarOffice -> OpenOffice Draw/Impress legacy
are derived from raster screen bitmap graphics which has maintained the text
"print" centric practice and uses a smallest "Field_Unit" of twips for
calculations of placement onto the canvas.

A twip (1/1440") --from Postscript 1/72" point-- is a screen independent
value converted (and rounded) in calculating vertex placements as pixel
dimensions. There are routines to convert measurement from twip to mm or
inch--but they are equally imprecise for use in CAD.

Meaning there is no history for vector based measurements (vertex, angles,
radius, and distances) needed for CAD. What is provided is all geared to
rendering bitmap onto a raster canvas--for resample to screen pixels.

So, the "arbitrary" lack of precision is a function of the resampling to
"fit" bitmap elements to pixels of a raster screen. wo Floating point
precision of measurements remains much less significant than performance for
rendering the twip derived document canvas. Yes there was a tradeoff, but an
easy one to make.

If you need the precision for CAD you want a program designed to handle
vectors under the hood, not bitmaps--period!

#13

Hi Dave,

dave boland schrieb:

Thanks all. If I make a suggestion to LO - add some more CAD abilities
to Draw such as higher precision.

The current internal precision is 1/100 mm. Armin Le Grand had started to change Draw to number format double to allow higher precision, see https://wiki.openoffice.org/wiki/Aw080_documentation. Unfortunately there is currently no Company which will pay for finishing that work.

You can get a very high precision in the UI, if you view the drawing with 3000% zoom and move/scale the objects using the array keys together with the Alt-key.

If you insist on the inch system, and need fractions of inches, you should change the unit from inch to point. It is 72 point = 1 inch, so 0.125 inch can be entered as 9 point, and with such number there is no problem in the UI. But you should notice that 1 inch = 2.54 cm and therefore 0.125 inch = 0.3175 cm = 317.5 * 1/100mm. It cannot be represented exactly with the internal 1/100mm unit.

But if your drawing needs a higher precision than 1/100mm and needs an 1:1 scale, then LibreOffice is the wrong tool.

   LOD is a very useful program, and

could be even more useful.

Draw can already do much more as the most users can imagine. Only the UI needs improvements for power users.

Kind regards
Regina

#14

Whatever the internals within LO, the present behaviour is irrational. Yes, obviously everything /eventually/ has to be adjusted some arbitrary grid size. However, there's no reason at all for arbitrary roundings before printing.

In particular, I've just experimented to see what's stored. I draw a single line and position it (or try to!) at 1.234cm from the margin (itself set at 1cm). I do this twice, with units set to cm (which forces a rounding to 2.34cm) and them mm (retains 2 dp's in/mm/ this time).

The generated contents.xml has a draw:line element, whose position is in the first case svg:x1="2.23cm" and in the second svg:x1="2.234cm". So the

They really, really ought to be the same. If the user chooses to work in cm, mm, or cubits, the available physical precision should nevertheless be ultimately defined by what the printing system can do.

OTOH, if the stored measurements are rounded to some arbitrary grid, then my two files should have the same rounded content.

Final experiment. Set the units to feet - and see how the precision drops to about 3mm because the entries are rounded by the GUI to 2 dp in feet. Rational behaviour? Not from a user's POV.

#15

Dave,
Depending on what you are going to draw; if anything either technical or building/cottage then you can try either ProgeCAD Smart 2009 or Draftsight, both have free versions that are fully functional 2D CAD programs for private use only.
Especially Draftsight is quite easy to learn.
Download from their own homepage.
Pertti Rönnberg

#16

hello to all,i'm very interessing this particular "precision" intro from CAD, you can show to me (for all users can see your case particular), leave here link picture cad in LOD ok?
manuel

#17

A bit of a rant. My apologies and respect to all who have made Draw possible in advance.

Hi Dave,

dave boland schrieb:

Thanks all. If I make a suggestion to LO - add some more CAD abilities
to Draw such as higher precision.

The current internal precision is 1/100 mm. Armin Le Grand had started to change Draw to number format double to allow higher precision, see https://wiki.openoffice.org/wiki/Aw080_documentation. Unfortunately there is currently no Company which will pay for finishing that work.

Thank you for pointing this out.

You can get a very high precision in the UI, if you view the drawing with 3000% zoom and move/scale the objects using the array keys together with the Alt-key.

If you insist on the inch system, and need fractions of inches, you should change the unit from inch to point. It is 72 point = 1 inch, so 0.125 inch can be entered as 9 point, and with such number there is no problem in the UI. But you should notice that 1 inch = 2.54 cm and therefore 0.125 inch = 0.3175 cm = 317.5 * 1/100mm. It cannot be represented exactly with the internal 1/100mm unit.

If I insist on the inch system, I should use inches. Not meant to be harsh, but really?
Can't debate your math, but shouldn't data be entered as it is measured?

Using points makes "Dimension Lines" that result in points, not inches.

The "Draw" package should draw. "Artist", "Architectural", "Engineering", "Diagram", "Composition", "Graphic", "Technical"...

It does cover most of these well. Just not all.

But if your drawing needs a higher precision than 1/100mm and needs an 1:1 scale, then LibreOffice is the wrong tool.

Yes, I do have a CAD program (overly complex - wrong tool) and my frustration using it is because I can't use Draw (functions beyond CAD - right tool).

#18

Actually, all I'm doing is laying out a greeting card. The print shop
needs 1/8" margins, and I'm a stickler for detail. I agree that Scribus
or a CAD program has more flexibility, but I like LO.

Seems like the consensus is that my suggestion is possible, but will
have to wait for funding. Makes sense.

Dave

#19

Hi Paul,

Paul D. Mirowsky schrieb:

If I insist on the inch system, I should use inches. Not meant to be
harsh, but really?
Can't debate your math, but shouldn't data be entered as it is measured?

Using points makes "Dimension Lines" that result in points, not inches.

It is only a workaround to get the most possible precision entered in the UI. The unit of the dimension line is a different setting. That setting is in the style of the dimension line. You can show more than two decimal places and set the unit to "cm" or "inch" even if your global unit setting is "point".

Kind regards
Regina

#20

dave boland wrote

Actually, all I'm doing is laying out a greeting card. The print shop
needs 1/8" margins, and I'm a stickler for detail. ...

Set the page size first (to whatever the printer wants for the card), and
then from Tools -> Options -> Draw -> General set your "Unit of Measure"
to Points (1/72")

From the Page dialog you can set a margin of exactly 9 pt <= 180 twip =>
1/8", it will hold that on a Save/Print/Reopen but if you change the units,
i.e. mm or inch you may get some scaling.