Kobo Device Driver Update

[beedaddy]

@davidfor: I couldn't reproduce it with an other, free, book. So I'll send you a PM...

[davidfor]

@beedaddy: I have the sample and can reproduce the problem.

The problem is in how the stylesheet is processed. It is parsed by the CSS parser that calibre uses and the rules from the file added. Then it is written back to the epub and that is copied to the device. As part of this, the CSS is cleaned up and reformatted. The cleaning includes removing any styles that have no attributes. The reformatting adds or removes whitespace and changes number from ".8" to "0.8". None of this should be harmful and neither version shows any errors. This is the same as using the calibre editor to beautify the CSS.

But, on the device, the stylesheet is being ignored. That means that the RMSDK is seeing an error in the stylesheet and throwing it away. This also happens when I open the epub with ADE. The unchanged epub is fine in both places. But, let the driver add the styles, or beautify with the editor, and it is broken in both place.

I can't see what is wrong with the modified version. I have gone through both version of the stylesheet and can't see what would be causing the problem. I have extracted the original stylesheet and attached it. Hopefully someone can see what the problem is.

The workaround is to turn the modify CSS option off and edit the book and add widows/orphans to the stylesheet. When I did that, the sample displayed correctly.

[JSWolf]

Originally Posted by davidfor

I have extracted the original stylesheet and attached it. Hopefully someone can see what the problem is.

Where is the attached stylesheet (please attach both the working and non-working versions)? I'll take a look at it if I can find where it's been attached.

[beedaddy]

To be honest, I'm not happy with attaching the css of a non-free book.

[davidfor]

Originally Posted by JSWolf

Where is the attached stylesheet (please attach both the working and non-working versions)? I'll take a look at it if I can find where it's been attached.

Whoops. Apparently you can't attach a stylesheet and I didn't pay attention. I have added it as a zip file.

[jackie_w]

This stylesheet contains 3 occurrences of !important. You could try surgically removing them. I've had enough trouble with this in the past that I now always remove them before sending to a Kobo. If the css is well-designed it should never be needed anyway (IMO ). I've had numerous occurrences of an epub displaying on a Kobo as if none of the css was being used, i.e. everything left-aligned, no paragraph indents, 'blank line' between every paragraph. When I've opened up the epub to investigate it has always contained at least one !important. Removing them has always fixed my problem.

BTW, in addition, there doesn't seem to be a space before !important which I would have thought is an error, e.g.

div.abbildung.with_thumbnail p.link_toFullsize {
text-align:left;
text-indent:0!important;
}

[davidfor]

Originally Posted by jackie_w

This stylesheet contains 3 occurrences of !important. You could try surgically removing them. I've had enough trouble with this in the past that I now always remove them before sending to a Kobo. If the css is well-designed it should never be needed anyway (IMO ). I've had numerous occurrences of an epub displaying on a Kobo as if none of the css was being used, i.e. everything left-aligned, no paragraph indents, 'blank line' between every paragraph. When I've opened up the epub to investigate it has always contained at least one !important. Removing them has always fixed my problem.

BTW, in addition, there doesn't seem to be a space before !important which I would have thought is an error, e.g.

div.abbildung.with_thumbnail p.link_toFullsize {
text-align:left;
text-indent:0!important;
}

Yes, I thought of those. But, I couldn't see why they would cause the problem after a calibre editor beautify was run on it. I'll try removing them tonight to see what happens.

[JSWolf]

Originally Posted by beedaddy

To be honest, I'm not happy with attaching the css of a non-free book.

There is nothing wrong with attaching the CSS of a commercial eBook and the staff at MR won't have a problem.

[JSWolf]

delete post

[JSWolf]

One thing to do is use Calibre's eBook editor to remove all unused classes. That way if any of the unused classes is causing a problem. Even if that doesn't work, it will mean less classes to have to try to debug.

davidfor, please try this and see if things work. If not, please post the working CSS and the broken CSS (both after unused classes have been removed).

[davidfor]

Originally Posted by JSWolf

One thing to do is use Calibre's eBook editor to remove all unused classes. That way if any of the unused classes is causing a problem. Even if that doesn't work, it will mean less classes to have to try to debug.

davidfor, please try this and see if things work. If not, please post the working CSS and the broken CSS (both after unused classes have been removed).

Jon, guess what one of the first things I tried was? But, it doesn't really help solve the problem. I only have a small sample of the the book, so I don't know which classes are unused in the rest of the book. To find what is causing the problem, I have to remove the classes one at a time, do a beautify and test. Luckily, ADE shows the problem as well, so I don't have to keep putting it on a device.

[davidfor]

Originally Posted by beedaddy

To be honest, I'm not happy with attaching the css of a non-free book.

I've removed the file. It shouldn't cause a problem, but, it is your book, so your wishes are more important.

[NiLuJe]

First of all, sorry for digging up a relatively stale thread... .

Given the terrible rendering of covers in sleep mode, I quickly enabled the "B&W Covers" setting, but when that didn't help much, I took a look at the code: it basically just does what's on the tin, without dithering it down to the eInk 16 shades of grey palette.

Since I was in a hurry, I took a very dirty approach and applied this simple patch to the Calibre sources:

diff --git a/src/calibre/utils/magick/draw.py b/src/calibre/utils/magick/draw.py
index 73832a1..d0793c4 100644
--- a/src/calibre/utils/magick/draw.py
+++ b/src/calibre/utils/magick/draw.py
@@ -75,6 +75,7 @@ def save_cover_data_to(data, path, bgcolor='#ffffff', resize_to=None,
 
     if grayscale:
         img.type = "GrayscaleType"
+        img.quantize(number_colors=16, dither=1)
         changed = True
 
     if resize_to is not None:

It's dirty as hell, but it appears to be doing the job just fine. (Granted, the quantization step is expensive and appears to block the GUI, but, it works, I can now look at book covers without making my eyes bleed ;p).

I'm basically just throwing the idea out there to see if there's a way to handle that more gracefully .

[Granted, my opinionated position on this issue most likely stems from the pains I took to do it right with the Kindle's ScreenSavers hack ]

[jackie_w]

@ NiLuJe, Are my eyes deceiving me Has the community Kindle developer supremo really decided to dip his toes in Kobo H2O waters?

Well, whatever prompted your decision, welcome I hope you enjoy it and that the rest of us can look forward to more creative work from you, to add to the fabulous work of davidfor et al.

[NiLuJe]

@jackie_w: I dunno, it was winter, it was cold and grey, people kept asking me what I wanted for Christmas, the Voyage isn't available in France, the 5.6.1 update pissed us off, I broke down and went "What the hell!". .

I'm not terribly thrilled with either set of devices so far, but it's been interesting nonetheless ^^. (Also: an amazing new way to procrastinate! ^^)