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It's a very well thought through article by the developer of Nota, trying to bring EPUB format up to parity with PDF. It's a serious start and they've already w

It's a very well thought through article by the developer of Nota, trying to bring EPUB format up to parity with PDF. It's a serious start and they've already written a viewer. In fact, the article itself is displayed in a browser-based wasm port of the viewer (and looks good!). One issue is how precisely EPUB, which is really XHTML, can reproduce layout. What are the possibilities here? The OP's standard is that the document will look "reasonable". The imply that HTML would need new layout capabilities to match PDF, at least for line breaking: There's two ways to make progress here. One is for browsers to provide more typography tools. Allegedly, text-wrap: pretty is supposed to help, but in my brief testing it doesn't seem to improve line-break quality. The other way is to pre-calculate line breaks, which would only work for fixed-layout renditions. Also, though the author mentions annotations, I don't see how they intend to implement them.

joshjob42 3y ago
The author discusses fixed layout epubs. Effectively, the epub can give a default pagination, line-breaks, font, font size, page size, and positioning for images etc., making it render identically on everything (one might optionally omit pagination if opening in a browser but keep everything else). This can be done already in epub3. But that's not ideal, because then it doesn't look good anymore on a phone, etc. Depending on the reader though, you could override the default, but then you have to hope that your reader does a good job of making a nice document. An alternative is for the epub to specify multiple renderings, for various common screen types. I don't think this is unreasonable as a solution. By all means let's try to get a smart reader, but letting people create defaults for their documents that can be overridden if desired by the user is a good middle ground.
- idoubtit 3y ago
  Indeed, EPUB3 provides all the features that the author wishes. His "portable EPUB" format is just a loosely specified subset. It's unclear if some extra features are included in the format as they are in his "Bene" tool, like the rendering of references (i.e. links with a data-target attribute). The EPUB3 standard is much more complex than EPUB2 (media overlays, mixing fixed layout with reflowed, MathML…). In my experience the implementations are much more varying, and most of them aren't complete. So a "Portable EPUB" may not render as expected because the reader tool lacks some specific feature. The author also requires full JS support, which I supose does not help with portability.
zozbot234 3y ago
Doesn't CSS support layout capabilities for paged media out of the box? An EPUB reader just has to implement good old-fashioned "Print Preview" display mode, and you're set.
zdunn 3y ago
> Also, though the author mentions annotations, I don't see how they intend to implement them. It's discussed at the very end of section 8 and all of section 9 that interactive functionality would use web components.
nine_k 3y ago
PDF does not have any capabilities of line breaking. It is a picture format, similar to SVG, only more rigid. That's why it can't have text reflow, etc. What an ebook format needs is a semantic form of markup, which adapts to devices it is rendered on. HTML + CSS were invented for this goal. With that, book layout authors should consciously relinquish some control on how the book looks, and hand it to the reader. Slight visual imperfections are a small price to pay for this. Who needs visual perfection should go for a PDF. This, of course, becomes hard if any interactive stuff is involved. I would suggest that larger interactive elements should open in a dedicated view when needed, and tiny interactive elements should embrace reflow.
- kps 3y ago
  > HTML + CSS were invented for this goal. HTML (with SVG and MathML) is probably fine for most books, but CSS has spent 30 years resolutely resisting basic typography, i.e. default text baseline alignment.
- wolverine876 3y ago
  You will enjoy the article, which goes into these issues in some detail.
BlueTemplar 3y ago
Ironically, the very example the author uses for annotations doesn't work properly for me : on touchscreen Android Firefox I get a link instead of a popup when press-holding. And aren't annotations (and references) already part of the EPUB specification, and probably even the HTML specification ?!? Finally, I disagree with the press-and-hold for popup being better than the usual practice of hyperlink anchors, IMHO their jumping around is much less disruptive. (As long as the reader's "return" function is working properly, and/or - for the bijective ones - they provide a "back" hyperlink.)
- wolverine876 3y ago
  > And aren't annotations (and references) already part of the EPUB specification I'm pretty sure they are not, based on looking carefully a year or two ago, on recent discussions here on HN, and on the OP's belief that they need to invent it.
int_19h 3y ago
Back in the day, there was something called XSL Formatting Objects (XSL-FO). Meant to be something like XML-based PDF, but somewhat higher level - e.g. it did text reflow. The idea was that you'd distribute an XML document combined with an XSL stylesheet that would transform it to FO for rendering; and the same document could have multiple stylesheets for different target devices, page sizes etc.
- wolverine876 3y ago
  I suppose EPUB could have multiple style sheets and provide defaults for various uses. Professional publishers could do something fancy and beautiful, companies could have their own defaults, individuals could use the EPUB defaults, and there could be FOSS stylesheets that people download and use as desired.

joshjob42 3y ago

The author discusses fixed layout epubs. Effectively, the epub can give a default pagination, line-breaks, font, font size, page size, and positioning for images etc., making it render identically on everything (one might optionally omit pagination if opening in a browser but keep everything else). This can be done already in epub3. But that's not ideal, because then it doesn't look good anymore on a phone, etc. Depending on the reader though, you could override the default, but then you have to hope that your reader does a good job of making a nice document. An alternative is for the epub to specify multiple renderings, for various common screen types. I don't think this is unreasonable as a solution. By all means let's try to get a smart reader, but letting people create defaults for their documents that can be overridden if desired by the user is a good middle ground.

idoubtit 3y ago
Indeed, EPUB3 provides all the features that the author wishes. His "portable EPUB" format is just a loosely specified subset. It's unclear if some extra features are included in the format as they are in his "Bene" tool, like the rendering of references (i.e. links with a data-target attribute). The EPUB3 standard is much more complex than EPUB2 (media overlays, mixing fixed layout with reflowed, MathML…). In my experience the implementations are much more varying, and most of them aren't complete. So a "Portable EPUB" may not render as expected because the reader tool lacks some specific feature. The author also requires full JS support, which I supose does not help with portability.

zozbot234 3y ago

Doesn't CSS support layout capabilities for paged media out of the box? An EPUB reader just has to implement good old-fashioned "Print Preview" display mode, and you're set.

zdunn 3y ago

> Also, though the author mentions annotations, I don't see how they intend to implement them. It's discussed at the very end of section 8 and all of section 9 that interactive functionality would use web components.

nine_k 3y ago

PDF does not have any capabilities of line breaking. It is a picture format, similar to SVG, only more rigid. That's why it can't have text reflow, etc. What an ebook format needs is a semantic form of markup, which adapts to devices it is rendered on. HTML + CSS were invented for this goal. With that, book layout authors should consciously relinquish some control on how the book looks, and hand it to the reader. Slight visual imperfections are a small price to pay for this. Who needs visual perfection should go for a PDF. This, of course, becomes hard if any interactive stuff is involved. I would suggest that larger interactive elements should open in a dedicated view when needed, and tiny interactive elements should embrace reflow.

kps 3y ago
> HTML + CSS were invented for this goal. HTML (with SVG and MathML) is probably fine for most books, but CSS has spent 30 years resolutely resisting basic typography, i.e. default text baseline alignment.
wolverine876 3y ago
You will enjoy the article, which goes into these issues in some detail.

BlueTemplar 3y ago

Ironically, the very example the author uses for annotations doesn't work properly for me : on touchscreen Android Firefox I get a link instead of a popup when press-holding. And aren't annotations (and references) already part of the EPUB specification, and probably even the HTML specification ?!? Finally, I disagree with the press-and-hold for popup being better than the usual practice of hyperlink anchors, IMHO their jumping around is much less disruptive. (As long as the reader's "return" function is working properly, and/or - for the bijective ones - they provide a "back" hyperlink.)

wolverine876 3y ago
> And aren't annotations (and references) already part of the EPUB specification I'm pretty sure they are not, based on looking carefully a year or two ago, on recent discussions here on HN, and on the OP's belief that they need to invent it.

int_19h 3y ago

Back in the day, there was something called XSL Formatting Objects (XSL-FO). Meant to be something like XML-based PDF, but somewhat higher level - e.g. it did text reflow. The idea was that you'd distribute an XML document combined with an XSL stylesheet that would transform it to FO for rendering; and the same document could have multiple stylesheets for different target devices, page sizes etc.

wolverine876 3y ago
I suppose EPUB could have multiple style sheets and provide defaults for various uses. Professional publishers could do something fancy and beautiful, companies could have their own defaults, individuals could use the EPUB defaults, and there could be FOSS stylesheets that people download and use as desired.