EPUB2 to EPUB 3 errors

[KevinH]

Hi Psymon,

Yes, I edited my response as I did not see you had already posted. You want to add the audio file and make any changes you want on the epub2 side of things and *THEN* run epub3-itizer.

On the good news front, this bug does not exist in Sigil master (Sigil-0.9.4) as we have already reworked the complete Metadata gui editor and in doing that prevent the bug. I did try your test case on it and it passes with flying colours even if I add the audio file later. So all should work much better in Sigil-0.9.4 which should be out in under two weeks (barring bugs).

Thanks so much for the bug report!

KevinH

[Psymon]

Originally Posted by KevinH

Yes, I edited my response as I did not see you had already posted. You want to add the audio file and make any changes you want on the epub2 side of things and *THEN* run epub3-itizer.

That's awesome. I'm VERY curious to try this out now! Might take me a bit (I have to fix up all those other errors first again, and it's suppertime, etc. at the moment) but I'll get back to you and let you know how things turn out.

On the good news front, this bug does not exist in Sigil master (Sigil-0.9.4) as we have already reworked the complete Metadata gui editor and in doing that prevent the bug. I did try your test case on it and it passes with flying colours even if I add the audio file later. So all should work much better in Sigil-0.9.4 which should be out in under two weeks (barring bugs).

Oh, doubly-awesome! I didn't realize that you actually were working on Sigil, I thought you were just involved with the epub3itizer plugin. Right on, dude! I really, really, REALLY like Sigil -- so much so, in fact, that I've even wondered if there's a way that I could use it as my HTML editor for web design. The biggest limitation in that, though, is the directory structure that you're "stuck" with -- but hey, ya know, if you tweaked the program a bit, you could probably also come up with THE best non-WYSIWYG HTML editor out there!

[Psymon]

Yaaaay! Success! I got it working, with 289 warnings (still), but NO errors!

Re all those SVG link errors, earlier you'd written this...

Originally Posted by KevinH

Your book has many sections like the following in its code:

  <div class="svg_outer">
    <div class="svg_inner">
      <svg height="94%" version="1.1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1200 1800" preserveAspectRatio="xMidYMid meet" width="94%" xmlns:xlink="http://www.w3.org/1999/xlink"><image height="1800" id="title-original" width="1200" xlink:href="../Images/walden-titlepage.jpg"/></svg>
    </div>
  </div>

It is just a warning that says your need to add an xlink:title="Walden-TitlePage-Image" attribute (or something along those lines).

This has nothing to do with epub3-itizer operation. And they are just warnings and can be ignored.

I couldn't figure out where to put that xlink:title bit -- I tried within the above <image> part, and that didn't validate, and then put it in the <svg> part before that, and that's wrong, too (I just did a quick search & replace and inserted xlink:title="image" in there for now, without getting more descriptive).

In any case, I'll take your word for it that I can ignore all those warnings -- I guess it's just always nice when you run it through epubcheck and get that lovely (and brief) "No errors or warnings detected" report back. But I guess I can live with all those warnings -- I'm certainly far from perfect, too, and I've lived with myself for all these years just fine.

Thanks so much once again, Kevin -- you rock!

[KevinH]

The more I read up on that warning, the more I think it is a bug in epubcheck. AFAICT, the xlink:title attribute only is needed for svg anchor "a" tags. Svg has its own "a" tag. So your image tags should not need it. Could it be your code is simply missing the svg close tag in places that results in anchor tags being subsumed into the svg namespace?

Does your code ever use an svg anchor "a" tag?

KevinH

[Bertrand]

I have the same error message in one of my epub.
I have two inline svg, no links inside, no links in the whole xhtml file.
I've tried every possible variations, with "title", "xlink:title", tried to put them inside/outside/between the svg tag, the path tag, etc., no luck... Always the same warning.
It's just a warning but still... It's irritating :-)

[Psymon]

Originally Posted by KevinH

Could it be your code is simply missing the svg close tag in places that results in anchor tags being subsumed into the svg namespace?

I have no idea, but if that error was there, then wouldn't it show up when I validate my EPUB2 version? It's only after I convert it to EPUB3 that I get all those errors -- when I validate my EPUB2, before converting, I get "no errors or warnings" (just the way I like it!).

Does your code ever use an svg anchor "a" tag?

I don't even know what an svg anchor "a" tag looks like -- if one refers to an "a" tag, I think <a href="whatever">. I'm rather clueless when it comes to SVG stuff, really.

Also...

Originally Posted by Bertrand

It's just a warning but still... It's irritating :-)

Yeah, totally.

[KevinH]

I am almost certain this is an epubcheck bug. What exact version of epubcheck are you using? The code that sets that warning should only trigger in anchor tags in svg and not in svg image tags. So something funny is going on. I looked at epubcheck-4.0.1 and they have moved where and how they produce this warning, so perhaps the error has already been fixed.

KevinH

[Psymon]

Originally Posted by KevinH

I am almost certain this is an epubcheck bug. What exact version of epubcheck are you using? The code that sets that warning should only trigger in anchor tags in svg and not in svg image tags. So something funny is going on. I looked at epubcheck-4.0.1 and they have moved where and how they produce this warning, so perhaps the error has already been fixed.

You have epubcheck-4.0.1? Okay, I must be confused again. I have that Pagina epubchecker, which I thought was simply a GUI interface for epubcheck (so you don't have to run it from a command prompt). If that's right, then when I go under "About" -> "Check for updates" it tells me that I do have the latest version. I don't see version "4.0.1" of anything anywhere, though, rather it tells me that I have version 1.60 (of Pagina).

In any case, it does tell me that I have the latest version -- supposedly.

EDIT/CORRECTION: Oh! Ha ha, now I do see "epubcheck 4.0.1", right under the "validate" button.

[KevinH]

This inability to prevent the warning with the latest epubcheck 4.0.1 version really bothers me. So I have created an epubcheck issue on github asking if the epubcheck validator was even correct in this case and if so, how should the warning be prevented. My personal opinion is that it is a bug. Somehow the warning gets triggered by an xlink:href in an svg "image" element but epubcheck does not actually look at that same "image" element to determine if a xlink:title attribute actually exists. Epubcheck should simply not generate a warning if there is no way to prevent it! The idea behind the warning is to convince users to add accessibility information (such as a title that explains what is going on) but adding the title doesn't seem to prevent the warning which defeats the whole purpose.

I will let you know if and when I receive a response on how best to "fix" this.

KevinH

[Psymon]

Originally Posted by KevinH

My personal opinion is that it is a bug. Somehow the warning gets triggered by an xlink:href in an svg "image" element but epubcheck does not actually look at that same "image" element to determine if a xlink:title attribute actually exists.

Except those 200+ warnings that I got seem to all point to places where I don't even have an SVG image! I didn't go through them all, but I think that the warnings occur where I have a link in my text which points to an SVG image. I think you said you downloaded my book, eh? If you run it through epubcheck then no doubt you'll see what I mean (if you can be bothered).

[KevinH]

Hi Psymon,
That is not consistent with what Bertrand reported. I assumed you were both talking about the same warning. If you remember, I did ask you earlier if you had anchors in your file to try and rule that out.

So these are caused by normal html anchors pointing to an svg external image file? Or is it an anchor pointing toward an html location just before or after the svg embedded in html? Or is it an img tag pointing to an external svg image file?

The problem is in none of these cases would an xlink:title attribute be appropriate. It is really only appropriate in standalone svg file, and svg embedded inside xhtml or svg image tag.

I will look again at your code when I get back from work to see if I can figure out what is really going on. The warning you are getting just makes no sense if adding xlink:title to the svg image tag does not prevent the warning.

KevinH

[KevinH]

Psymon,

Then where exactly do they point in your code? Can you point me at one specific place in your code and the exact line number and warning message generated?

Originally Posted by Psymon

Except those 200+ warnings that I got seem to all point to places where I don't even have an SVG image! I didn't go through them all, but I think that the warnings occur where I have a link in my text which points to an SVG image. I think you said you downloaded my book, eh? If you run it through epubcheck then no doubt you'll see what I mean (if you can be bothered).

KevinH

[Psymon]

Originally Posted by KevinH

Then where exactly do they point in your code? Can you point me at one specific place in your code and the exact line number and warning message generated?

Well, let's see... the first warning I get reads as follows...

WARNING (ACC-011) at "Thoreau-Walden_and_Beyond0112b (EPUB3).epub/OEBPS/Text/about-koster-penman.xhtml" (line 50, col 252):
SVG hyperlinks should have a human-readable title (using the 'title' child element or the 'xlink:title' attribute).

...and line 50 in the file mentioned is the following paragraph...

<p class="text" style="text-indent: 0em;"><b style="font-size:262%;">I</b><span class="smallcaps">N</span> the aim of creating a “colour photograph” of Henry David Thoreau — which you can view at the <a href="#penman-artwork">end of this chapter</a> — <span class="nowrap">I decided</span> to start with the daguerreotype taken by Benjamin D. Maxham at Worcester, Massachusetts on June 13^th, 1856, as shown on the <a href="#maxham">preceding page</a>. In fact, three of these portraits were made at that time; however, they are all virtually identical except for minor, negligible differences. These daguerreotypes were done initially at the request of a Rochester, Michigan admirer named Calvin H. Greene, who had sent Thoreau $5^.00 so that he could have one made for himself, and also asking that copies of Thoreau’s two books be sent to his brother in California. Thoreau had earlier responded to Greene’s request for a portrait by writing to him that he would “[.*.*.] have the best of me in my books [.*.*.] I am not worth seeing personally — the stuttering, blundering, clod-hopper that I am,” but eventually the portraits would be done and Greene was sent one along with a letter which said, in part, “While in Worcester this week I obtained the accompanying daguerreotype — which my friends think is pretty good — though better looking than I.” In addition to the portrait and letter, Thoreau also included $1^.70 in change (the two other daguerreotypes made at that time were given to Thoreau’s Worcester friends H.G.O. Blake and Theo. Brown).</p>

I can only assume that "col 252" (mentioned in the epubcheck warning) is the link in the above paragraph that reads...

<a href="#maxham">preceding page</a>

...which is a link pointing to an SVG image ("maxham").

I have 292 of these warnings -- and I certainly don't have that many SVG images! It's hard to believe that I have that many HTML links within the book that point "to" SVG images, too, but it's a pretty huge book, so maybe I do.

I don't know -- what the heck to I know?

[KevinH]

Psymon,

You seem to be linking directly inside of an svg element.

as shown on the <a href="#maxham">preceding page</a>.

This maxham link points to deep inside the svg code into the image tag itself. Notice the id="maxham" attribute on the svg image tag.

 <div class="svg_outer">
    <div class="svg_inner">
      <svg xmlns="http://www.w3.org/2000/svg" height="94%" 
preserveAspectRatio="xMidYMid meet" version="1.1" viewBox="0 0 1200 1800" 
width="94%" xmlns:xlink="http://www.w3.org/1999/xlink"><image height="1800"
id="maxham" width="1200" xlink:href="../Images/penman-maxham.jpg" />
      </svg>
    </div>
  </div>

FWIW, in general it is probably not a good idea to link into the very middle of an svg element from an xhtml section. It is much safer for the destination of the link to be an xhtml element that precedes the svg section.

So will you please try changing this one piece of code to the following to see if it prevents this particular warning:

 <div id="maxham" class="svg_outer">
    <div class="svg_inner">
      <svg xmlns="http://www.w3.org/2000/svg" height="94%" 
preserveAspectRatio="xMidYMid meet" version="1.1" viewBox="0 0 1200 1800" 
width="94%" xmlns:xlink="http://www.w3.org/1999/xlink"><image height="1800" 
width="1200" xlink:href="../Images/penman-maxham.jpg" />
      </svg>
    </div>
  </div>

Notice how I have moved the "id" attribute to the xhtml div holding the svg elements.

Please give that a try and let me know if it removes that warning.

KevinH

[Psymon]

Originally Posted by KevinH

Notice how I have moved the "id" attribute to the xhtml div holding the svg elements.

Please give that a try and let me know if it removes that warning.

Went through my whole EPUB2 file and changed that on all the SVG images (there's 19 in all -- not too much trouble, really), converted to EPUB3 and then ran it through epubcheck...

...and I still have 292 warnings (same as before).