Question about empty page visible in Calibre - Page 2

eschwartz · 05-19-2015, 02:35 PM

Quote:

Originally Posted by chaley

Assuming that the rendering device is not doing something special, with that HTML there should be a single space output after the image. If the image consumes the entire screen then that space could appear on the next page.

The space is caused by the return between and </body>. Does the problem happen if the HTML looks like the following?

Code:

...20af-002.jpg" /></p></body></html>

HTML ignores spaces between tags. beautify/pretty print algorithms routinely reindent the structure in order to create that exact return -- as well as many more -- with absolutely no effect on rendered layout.

Chances are it is like theducks said.

theducks · 05-19-2015, 03:22 PM

Understand the W3C 'The Box Model'

Outer is Page
Next is Body
which contains 1 or more Block (P, Div...)
Blocks have (*but not all are visible or used)

Margin: The edges
Border:* Lines surrounding: 0 size is default
Padding:* Space from border to Text. default is small
Text/Image

You can do some fun/amazing stuff with a Single block (box) once you wrap your head around boxes

chaley · 05-19-2015, 03:56 PM

Quote:

Originally Posted by eschwartz

HTML ignores spaces between tags. beautify/pretty print algorithms routinely reindent the structure in order to create that exact return -- as well as many more -- with absolutely no effect on rendered layout.

Chances are it is like theducks said.

Years of experience with generating HTML tells me that whitespace between tags is not ignored, but is instead collapsed. I can't count the number of times that I had to remove returns from the HTML to avoid extra spacing between elements. Google also agrees with me, with zillions of pages talking about how to avoid the extra spaces introduced by line feeds by setting various font properties on the body tag and putting the tag closing > on the next line. And in any event, the space I was referring to is not between tags, it is a first class character in the body.

However, I could easily to be wrong now. The world has moved on in the 4 or 5 years since I last did this sort of thing, and the book rendering engines could be special purpose.

eschwartz · 05-19-2015, 04:05 PM

Quote:

Originally Posted by chaley

Years of experience with generating HTML tells me that whitespace between tags is not ignored, but is instead collapsed. I can't count the number of times that I had to remove returns from the HTML to avoid extra spacing between elements. Google also agrees with me, with zillions of pages talking about how to avoid the extra spaces introduced by line feeds by setting various font properties on the body tag and putting the tag closing > on the next line. And in any event, the space I was referring to is not between tags, it is a first class character in the body.

However, I could easily to be wrong now. The world has moved on in the 4 or 5 years since I last did this sort of thing, and the book rendering engines could be special purpose.

Between tags == [ignoredcollapsed spaces] </body>

Considering that both calibre and Sigil explicitly add those spaces (Beautify/Pretty Print) I shouldn't think those would be a problem. Perhaps they once were?

chaley · 05-19-2015, 04:19 PM

Quote:

Originally Posted by eschwartz

Between tags == [ignoredcollapsed spaces] </body>

Considering that both calibre and Sigil explicitly add those spaces (Beautify/Pretty Print) I shouldn't think those would be a problem. Perhaps they once were?

Try the following html

Code:

<html>
<body>
<font color="red">hi</font>
<font color="green">there</font>
</body>
</html>

At least on Chrome you will see that there is a space between "hi" and "there". Clearly the return is not being ignored but is instead converted to white space even though it is "between tags". That space will not be there if there is no return after the first . If a pretty printer adds such a return then it changes the output.

I found HTML rules for white space to be fiendishly complicated. They are dependent on the rendering engine and the semantics of the tags surrounding the white space. My experience is that if the tag does not generate white space on its own ( does) then one may or may not see the white space implied by the returns.

gbm · 05-19-2015, 04:52 PM

For your cover change:

Spoiler:

to

Spoiler:

Find the image width and height using calibre ebook editor, and enter them in-place of the xxx and XXX.

luck
bernie

eschwartz · 05-19-2015, 08:01 PM

Quote:

Originally Posted by chaley

Try the following html

Code:

<html>
<body>
<font color="red">hi</font>
<font color="green">there</font>
</body>
</html>

At least on Chrome you will see that there is a space between "hi" and "there". Clearly the return is not being ignored but is instead converted to white space even though it is "between tags". That space will not be there if there is no return after the first . If a pretty printer adds such a return then it changes the output.

I found HTML rules for white space to be fiendishly complicated. They are dependent on the rendering engine and the semantics of the tags surrounding the white space. My experience is that if the tag does not generate white space on its own ( does) then one may or may not see the white space implied by the returns.

As I understand it, whitespace (including the EOL character) is collapsed into one standard space within a block-level tag, and is ignored entirely if outside a block-level tag.

 is a block-level tag, and whitespace after a and before a </body> is ignored, but is an inline tag and spaces appear (collapsed) just like they do between words of plain text, or separated using span,em,b,i,strong, etc.

Your example has inline tags floating in a raw <body>, so I think the parser just throws up its hands and pretends there is a div or something there, but note that

Code:

<html>
<body>
<font color="red">hi</font>
<font color="green">there</font>
       
</body>
</html>

displays none of the linebreak + 7 spaces I inserted.

As for generating its own linebreak, it only defines a content block, and block-level tags are separated from other block-level tags by a linebreak.

eschwartz · 05-19-2015, 08:03 PM

Quote:

Originally Posted by gbm

For your cover change:

Spoiler:

to

Spoiler:

Find the image width and height using calibre ebook editor, and enter them in-place of the xxx and XXX.

luck
bernie

Sigil/calibre editor has a tool to add a cover page, and will auto-generate an SVG wrapper with the right values.

cybmole · 05-20-2015, 12:31 AM

Quote:

Originally Posted by chaley

...At least on Chrome you will see that there is a space between "hi" and "there". Clearly the return is not being ignored but is instead converted to white space even though it is "between tags". That space will not be there if there is no return after the first . If a pretty printer adds such a return then it changes the output.

I found HTML rules for white space to be fiendishly complicated. They are dependent on the rendering engine and the semantics of the tags surrounding the white space.....

yes, when your earlier post #9 popped up in my tapatalk app, the quoted code not display the space you were referring to. I can see it in chrome on on PC
so tapatalk renders differently to chrome, thus making your point

Marjelle · 05-21-2015, 07:43 AM

About the empty pages that emerge after the Cover page and before the Register and about size. The tutorial of ComputerTotaal advised size 600x900, when I then got an empty page after the Cover I already shrunk the Cover image to size 534x800 and this had no effect, still the empty page emerged.
When I experimented with Add-in for Word, the empty page disappeared, however I problably can't use that option for other reasons.

PeterT · 05-21-2015, 07:54 AM

Often problems like this can be solved very easily if an example ePub with this issue is uploaded. Any chance you can upload either the ePub in question, or one that has been created solely to demonstrate the issue?

HarryT · 05-21-2015, 07:56 AM

Quote:

Originally Posted by PeterT

Often problems like this can be solved very easily if an example ePub with this issue is uploaded. Any chance you can upload either the ePub in question, or one that has been created solely to demonstrate the issue?

... but not if it's copyrighted material, please.

PeterT · 05-21-2015, 08:15 AM

Quote:

Originally Posted by HarryT

... but not if it's copyrighted material, please.

Which is why I suggested creation of a book solely to demonstrate the issue. I made the assumption that the author would realize it should be non copyrighted material.

HarryT · 05-21-2015, 08:19 AM

Quote:

Originally Posted by PeterT

Which is why I suggested creation of a book solely to demonstrate the issue. I made the assumption that the author would realize it should be non copyrighted material.

I know that you meant that, Peter. Unfortunately we do sometimes get people who don't realise, though, hence the specific request. Easier to ask up front than to have the hassle of dealing with copyrighted material being uploaded.

Marjelle · 05-22-2015, 12:39 PM

Hi PeterT and HarryT, thanks for your reply. Someone has offered to help me, so I hope he finds out what exactly the problem is with the empty page that emerges after the Cover page and before the Register.

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05-19-2015, 03:22 PM	#17
theducks Well trained by Cats Posts: 31,072 Karma: 60358908 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	Understand the W3C 'The Box Model' Outer is Page Next is Body which contains 1 or more Block (P, Div...) Blocks have (but not all are visible or used) Margin: The edges Border: Lines surrounding: 0 size is default Padding:* Space from border to Text. default is small Text/Image You can do some fun/amazing stuff with a Single block (box) once you wrap your head around boxes

05-21-2015, 07:43 AM	#25
Marjelle Member Posts: 21 Karma: 10 Join Date: May 2015 Device: none	About the empty pages that emerge after the Cover page and before the Register and about size. The tutorial of ComputerTotaal advised size 600x900, when I then got an empty page after the Cover I already shrunk the Cover image to size 534x800 and this had no effect, still the empty page emerged. When I experimented with Add-in for Word, the empty page disappeared, however I problably can't use that option for other reasons.

05-21-2015, 07:54 AM	#26
PeterT Grand Sorcerer Posts: 13,535 Karma: 78910202 Join Date: Nov 2007 Location: Toronto Device: Libra H2O, Libra Colour	Often problems like this can be solved very easily if an example ePub with this issue is uploaded. Any chance you can upload either the ePub in question, or one that has been created solely to demonstrate the issue?

05-22-2015, 12:39 PM	#30
Marjelle Member Posts: 21 Karma: 10 Join Date: May 2015 Device: none	Hi PeterT and HarryT, thanks for your reply. Someone has offered to help me, so I hope he finds out what exactly the problem is with the empty page that emerges after the Cover page and before the Register.

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