any reason to avoid px measurements in epub?

[gluejar]

I'm working on some legacy html -> epub conversion software for Project Gutenberg.

It removes css rules that use px measurements. I have no idea why. Are there obscure or legacy epub readers that don't support px in css?

Eric

[phillipgessert]

It's because px are a fixed unit and don't account for e.g. reader-side font resizing or the wide variety of resolutions on different devices. Pretty much the same reason px have fallen out of favor in web design.

[JSWolf]

Originally Posted by gluejar

I'm working on some legacy html -> epub conversion software for Project Gutenberg.

It removes css rules that use px measurements. I have no idea why. Are there obscure or legacy epub readers that don't support px in css?

Eric

You don't need this legacy software. You can use Sigil or Calibre to turn this HTML into ePub.

Use em instead of px. For example, text-indent: 1.2em;

[Turtle91]

The only time I use px measurements are when I'm trying to limit the maximum size of an object. For example, an older book might have small images. I want the image to fill the screen as much as possible without getting over-stretched and blurry. In that case I would set the image width to be 85% of the screen, with a maximum width of the original image width.

ExampleImage.jpg = 500 x 800 pixels (w x h)

div {margin:2em auto; width:85%}
img {width:100%, max-width:500px}

<div><img alt="" src="../Images/ExampleImage.jpg" /></div>

Other than that, I would want to use measurements that keep everything relative to the user selected font/margin sizes - like 'em'.

[hobnail]

Hopefully that conversion software also removes or converts other fixed units like inches, cm, etc. for the reason phillipgessert gave.

When you say "working on" are you using the software to do conversions or are you updating/translating it? I've always been curious about what the workflow is that PG uses for making their ebooks.

[Tex2002ans]

Originally Posted by hobnail

I've always been curious about what the workflow is that PG uses for making their ebooks.

Digital Proofreaders creates a lot of the Project Gutenburg books:

https://www.pgdp.net/c/

You can read about the process there. Also, their forums are a trove of book digitizing information too:

https://www.pgdp.net/phpBB3/

[gluejar]

Originally Posted by phillipgessert

It's because px are a fixed unit and don't account for e.g. reader-side font resizing or the wide variety of resolutions on different devices. Pretty much the same reason px have fallen out of favor in web design.

My understanding is that as of css3, 1 px == 0.75 pt. So the same would apply to using pt? what about table border widths? should they be fixed or should they scale along with font resizing?

[gluejar]

Originally Posted by Tex2002ans

Digital Proofreaders creates a lot of the Project Gutenburg books:

https://www.pgdp.net/c/

You can read about the process there. Also, their forums are a trove of book digitizing information too:

https://www.pgdp.net/phpBB3/

It's the DP folks who want to keep the px in table border widths. The PG software "ebookmaker" takes DP books and makes epub.

[Turtle91]

Originally Posted by gluejar

My understanding is that as of css3, 1 px == 0.75 pt. So the same would apply to using pt? what about table border widths? should they be fixed or should they scale along with font resizing?

Generally borders should stay as px. It would be out of the ordinary to you find some situation that requires border thickness to change.

[gluejar]

Originally Posted by Turtle91

Generally borders should stay as px. It would be out of the ordinary to you find some situation that requires border thickness to change.

Thanks what I was thinking. Thanks!

[JSWolf]

Originally Posted by Turtle91

Generally borders should stay as px. It would be out of the ordinary to you find some situation that requires border thickness to change.

But, there is going to be a difference in border thickness when using a Reader witha n 800x600 screen vs a current 300DPI screen when using px. SO is px good to use in that case where you do not know what sort of Reader it may be read with?

[Turtle91]

Originally Posted by JSWolf

But, there is going to be a difference in border thickness when using a Reader witha n 800x600 screen vs a current 300DPI screen when using px. SO is px good to use in that case where you do not know what sort of Reader it may be read with?

Can you render a border with 1/2 a pixel?

Per W3Schools:

The width can be set as a specific size (in px, pt, cm, em, etc) or by using one of the three pre-defined values: thin, medium, or thick.

If you really want to use EM to define a border width, Jon, then you are certainly welcome to. I won't. It would take a great deal of fine-tuning to make it look decent. For the OP's consideration about automated software conversion - I would definitely not recommend it.

[JSWolf]

Originally Posted by Turtle91

Can you render a border with 1/2 a pixel?

Per W3Schools:


If you really want to use EM to define a border width, Jon, then you are certainly welcome to. I won't.

So how would you get a border to be the same width on a Sony Reader and a Kobo Clara HD?

[hobnail]

Originally Posted by JSWolf

So how would you get a border to be the same width on a Sony Reader and a Kobo Clara HD?

Let's turn the question around; how would you do it using ems or percentages or whatever? I'm not averse to using ems or whatever for horizontal rules and black borders on tables and whatnot but I've never tried it and it seems like it would be tricky.

[hobnail]

Originally Posted by Tex2002ans

Digital Proofreaders creates a lot of the Project Gutenburg books:

https://www.pgdp.net/c/

You can read about the process there. Also, their forums are a trove of book digitizing information too:

https://www.pgdp.net/phpBB3/

Thanks. I'm not sure how I missed the formatting links on their pages given that I was looking there yesterday or the day before.