Designer 2 - Document unit is always "pt" when opening PDF

[Ronny Axelsson]

I read somewhere that this is as designed but in my opinion it is wrong that when opening a PDF in Designer 2 (or Publisher 2), the document unit is always "pt", no matter what unit it was when saved.
So even if we have a PDF created with "mm" as document unit, and the page size is "mm" when we open in Acrobat Reader, it will be "pt" in Designer.
Very irritating that we have to change this for every document.

Edited December 14, 2023 by Ronny Axelsson

[Hangman]

Hi @Ronny Axelsson and welcome to the forums,

The unit of measurement for PDF files is points so Affinity apps opening PDF files and defaulting to Points is correct.

You can change the units displayed in Acrobat Reader between Centimetres, Inches, Millimeters, Picas and Points in the same way you can change the units displayed in Affinity apps but it doesn't change the fact that PDF uses Points...

 

[Ronny Axelsson]

As you say, the PDF specification defines PDF units as 72 'points' to 1 inch, and that is how things are measured internally.
But just because it may be technically correct, it doesn't mean that it is right from a user's perspective.

I bet you cannot find one single user who prefers to work in points, and all other programs that I have around automatically convert to the user's preferred default unit when opening a PDF.
This includes Adobe Reader and Acrobat Pro as well as other PDF readers, CorelDRAW, Illustrator, office apps and web browsers.
They all have a user defined unit that they use instead of points, and I think it would rather practical if Affinity could do the same.
Of course we can change the unit after opening a PDF but it is easy to forget and could lead to confusion as we work.

Therefore I suggest that the Affinity apps automatically convert to default document unit, or that they add a dropdown menu to the PDF options dialog, and preferably a menu that remembers 'last used'.

Edited December 18, 2023 by Ronny Axelsson

[Ronny Axelsson]

FWIW, I made a small test where I created a new document in Designer, 100 x 100 mm, and added a square, 80 x 80 mm.
I exported to PDF and then opened this file in all apps I could think of.
They all showed a 100 x 100 mm document with a 80 x 80 mm square, all except Affinity Designer/Publisher/Photo.

[Hangman]

10 minutes ago, Ronny Axelsson said:

FWIW, I made a small test where I created a new document in Designer, 100 x 100 mm, and added a square, 80 x 80 mm.
I exported to PDF and then opened this file in all apps I could think of.
They all showed a 100 x 100 mm document with a 80 x 80 mm square, all except Affinity Designer/Publisher/Photo.

In the other applications are you Opening the PDF file so it is fully editable or are you Placing the PDF file meaning you can't make any physical changes to the PDF itself?

If you Place the PDF file in an Affinity Document set to mm the Affinity file will continue to use mm, it's only on opening the PDF so you can edit the file, i.e., edit, change and delete text or any other elements in the file that the file will be shown in points, which is correct.

In the same way the US Paper size unit of measurement is Inches and the EU paper size unit of measurement is mm, the PDF unit of measurement is points.

[Ronny Axelsson]

I opened the file in both Illustrator and Draw, and also in Libre Office Draw, and it took up the document default unit in all of them.
Importing or 'placing' a PDF is something different of course.
 

17 minutes ago, Hangman said:

In the same way the US Paper size unit of measurement is Inches and the EU paper size unit of measurement is mm, the PDF unit of measurement is points.

Sorry but I have to disagree, it is not the same thing.
I'm pretty sure all file formats have some kind of internal unit that probably none of us would understand, and therefore we have the choice to use a default unit that makes more sense.

[Hangman]

Regardless, it doesn't change the fact that the default unit of measurement for PDF files is Points so I would have to say that Affinity apps are opening PDF files correctly by displaying points. If you wish to display the file using alternative units of measurement then it's a single click...

[Ronny Axelsson]

Even though the internal default unit for PDF is points, there are very few (if any) users working with this unit, which means that all of us must remember to go in and change it every time we open a PDF, to make it easier to work and reduce the risk of mistakes.
All other software developers have apparently realized this, and a very simple and risk free change in the code could also benefit Affinity users.

[loukash]

3 minutes ago, Ronny Axelsson said:

there are very few (if any) users working with this unit

How do you know what all the other 1000000+ Affinity users are working with?!

[Ronny Axelsson]

1 hour ago, loukash said:

How do you know what all the other 1000000+ Affinity users are working with?!

Oh sorry, you are absolutely right, I do not know what unit people are working with.
It was just an assumption based on around twenty years of communication in the Corel public forums and beta forums, and I can honestly say that I don't think I've ever heard anyone working in 'points', which I think is rather logical since the 'point' doesn't have any use outside the graphic or typographic world.

Is it an Affinity thing?

[loukash]

3 minutes ago, Ronny Axelsson said:

the 'point' doesn't have any use outside the graphic or typographic world.

Guess what the target audience of the Affinity suite is?  

6 minutes ago, Ronny Axelsson said:

I don't think I've ever heard anyone working in 'points'

Back in the day, while working with QuarkXPress in the 1990s and InDesign in the 00s and 10s, my horizontal ruler setting always was mm, and my vertical ruler in pt.
Sadly, Affinity still doesn't have the option to combine ruler units, so when working on print layouts, I regularly have to switch between mm and pt back and forth.

So, now you've heard of "one", at last…  

[Ronny Axelsson]

I'll add you to my list of users working in points, loukash. 😊

I still believe most of us like working with a unit that is easy to understand and corresponds to the end result, be it millimeters or inches or pixels, and if you say you prefer to use points I believe you.

But what harm could it possibly do to allow the user to choose default unit for PDFs when other apps do, which was what this thread was about?
It's no big deal changing the unit afterwards but why should we have to do that every time?

 

[loukash]

29 minutes ago, Ronny Axelsson said:

most of us like working with a unit that is easy to understand and corresponds to the end result, be it millimeters or inches or pixels, and if you say you prefer to use points I believe you.

Diffent units are not meant to be "easy to understand".
Each unit for different purpose.

So it's exactly the other way around:
Users should learn to understand which unit is adequate for a given task.

31 minutes ago, Ronny Axelsson said:

But what harm could it possibly do to allow the user to choose default unit for PDFs when other apps do, which was what this thread was about?

Fair enough, there's no real harm. Point taken. (Pun intended. )

[thomaso]

2 hours ago, Ronny Axelsson said:

all file formats have some kind of internal unit that probably none of us would understand, and therefore we have the choice to use a default unit

No. Affinity documents save their unit, so if you open a document that was created in inches it will not open in your preferred millimetres.

3 hours ago, Ronny Axelsson said:

or that they add a dropdown menu to the PDF options dialog

This appears to already be present at the intersection of the two rulers via right click.

Although I prefer to work in mm  I appreciate the Affinity behaviour: Not only it reminds me that the source file was either a PDF or from a different country or continent, it also reduces possible confusion that may occur by decimal or rounded values. (Apple's Preview.app reports a PDF in A4 size as "21,01 x 29,71 cm")

[Hangman]

37 minutes ago, Ronny Axelsson said:

But what harm could it possibly do to allow the user to choose default unit for PDFs

Irrespective of the units used in a document, whether px, inches, mm, cm, picas, points or whatever, the exported PDF uses points or more technically, since PDF 1.6 it uses UserUnits so the unit you set in Affinity apps is not stored in the exported PDF file unlike Affinity Documents themselves so there is no way for Affinity apps to know which units of measurement you want to work in, some may wish to work in mm, others in inches or pixels depending on the end use of the artwork created...

Referencing ISO 32000-2:2020

"PDF defines a device-independent coordinate system that always bears the same relationship to the current page, regardless of the output device on which printing or displaying occurs. This device-independent coordinate system is called user space.

If coordinates in a PDF file were specified in device space, the file would be device-dependent and would appear differently on different devices.

Images specified in the typical device spaces of a 72-pixel-per-inch display and a 600-dot-per-inch printer would differ in size by more than a factor of 8 so an 8-inch line segment on the display would appear less than 1 inch long on the printer.

The length of a unit along both the x and y axes is set by the UserUnit entry (PDF 1.6) in the page dictionary. If that entry is not present or supported, the default value of 1 ⁄ 72 inch is used. This coordinate system is called default user space."

[Ronny Axelsson]

44 minutes ago, loukash said:

Users should learn to understand which unit is adequate for a given task.

Agree. And therefore I cannot see any reason to bring in units that are neither useful nor wanted for that given task. 😊

 

41 minutes ago, thomaso said:

Affinity documents save their unit, so if you open a document that was created in inches it will not open in your preferred millimetres.

Absolutely, but the unit is then set by a user for a reason.

 

23 minutes ago, Hangman said:

...there is no way for Affinity apps to know which units of measurement you want to work in, some may wish to work in mm, others in inches or pixels depending on the end use of the artwork created.

Exactly. And therefore it should be up to the user to choose a default unit that he or she wants to use for new documents and when opening certain file types.

[thomaso]

50 minutes ago, Ronny Axelsson said:

but the unit is then set by a user for a reason.

The decision for pt as default unit in the PDF specifications was done by users, too. With the goal to consider not only local habits but also additional technical aspects.

Note, different to an Affinity document a PDF does not have a certain resolution (while its containing objects do, which may differ between various objects). That's why we are asked to either choose a resolution from a menu or type a specific value or let Affinity estimate a resolution when opening a PDF – while the resolution influences the relative size values for pixel objects like placed images (e.g. "100%") in the Affinity UI. Accordingly opening a PDF is not just like opening an Affinity document and may cause unexpected results (… as @Hangman's quoted example from the PDF specs points out).

So, if I understand right, you either want to be able to set a default Affinity application preference for the unit that gets used generally when opening a PDF (… and a default resolution, too?) … or you just want to get the existing menu UI copied into the open dialog for PDF. – While the first solution might cause confusion and unexpected results for other users, the latter would simply move your current, manual 1-click choice to a different, earlier moment in the opening procedure (without an obvious advantage).

[Ronny Axelsson]

There are three ways to solve this issue (that apparently isn't an issue at all 😉) :

1. The unit could be picked from the default document settings, and this is how it is done in CorelDRAW and Illustrator, as far as I know.

2. There could be an option in Settings to choose whether to always use a certain unit (for PDF or maybe for all documents) or use the embedded unit.

3. There could be a menu in the PDF options dialog, same as the DPI menu, where we could choose unit or leave as is.
    This setting should then be remembered (this is how DPI works), meaning that you would only have to change it once.
    So no, it would not be the same as manually clicking the 'ruler menu' every time after opening a PDF.

[jmwellborn]

Old Parkinson’s Law:  people at a board meeting argue the longest over the size of the wastepaper baskets.