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Add to conversion documentation.

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John Schember 2009-10-26 19:16:52 -04:00
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src/calibre/manual/conversion.rst
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@ -306,6 +306,11 @@ the headers and footers and remove them. Remember that they operate on the inter
by the conversion pipeline. There is also a wizard to help you customize the regular expressions for
your document.
The header and footer regular expressions are used in conjunction with the remove header and footer options.
If the remove option is not enabled the regular expression will not be applied to remove the matched text.
As stated the removal works by using a python regular expression. All matched text is simply removed from
the document. You can learn more about regular expressions and the syntax at http://docs.python.org/library/re.html
Miscellaneous
~~~~~~~~~~~~~~
@ -419,7 +424,61 @@ generating the Table of Contents much simpler. It is called BookCreator and is a
Convert TXT documents
~~~~~~~~~~~~~~~~~~~~~~
TXT documents can contain any imaginable layout. Since TXT documents provide no way to explicitly mark parts of
the text, by default |app| only groups parts of the document into paragraphs. The default is to assume one or
more blank lines are a paragraph boundary.
.. code-block:: txt
This is the first.
This is the
second paragraph.
TXT input supports a number of options to differentiate how paragraphs are detected.
:guilabel:`Treat each line as a paragraph`
Assumes that every line is a paragraph.
.. code-block:: txt
This is the first.
This is the second.
This is the third.
:guilabel:`Assume print formatting`
Assumes that every paragraph starts with an indent (either a tab or 2+ spaces). Paragraphs end when
the next line that starts with an indent is reached.
.. code-block:: txt
This is the
first.
This is the second.
This is the
third.
:guilabel:`Process using markdown`
|app| also supports running TXT input though a transformation preprocessor known as markdown. Markdown
allows for basic formatting to be added to the document and is an easy way to differentiate non-paragraph
elements such as chapter headings. Marking chapter headings with # and settings the chapter XPath detection
expression to "//h:h1" is the easiest way to have a proper table of contents generated from a TXT document.
You can learn more about the markdown syntax at http://daringfireball.net/projects/markdown/syntax
Convert PDF documents
~~~~~~~~~~~~~~~~~~~~~~
PDF documents are one of the worst formats to convert from. They are a fixed page size and text placement format.
Meaning, it is very difficult to determine where one paragraph ends and another begins. |app| will try to unwrap
paragraphs using a configurable, :guilabel:`Line Un-Wrapping Factor`. This is a scale used to determine the length at which a line should be unwrapped. Valid values are a decimal
between 0 and 1. The default is 0.5, this is the median line length. Lower this value to include more
text in the unwrapping. Increase to include less.
Also, they often have headers and footers as part of the document that will become included with the text.
Use the options to remove headers and footers to mitigate this issue. If the headers and footers are not
removed from the text it can throw off the paragraph unwrapping.
Some limitations of PDF input is complex, multi-column, and image based documents are not supported.
Extraction of SVG images from within the document is also not supported.