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-How does it work?
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-The external material feature is based on the concept of a
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- template
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- A template is a specification of how LyX should interface with a certain
- kind of material.
- As bundled, LyX comes with predefined templates for XFig figures, Dia diagrams,
- various raster format images, gnuplot, and more.
- You can check the actual list by using the
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-External
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-
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-Material
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-command.
- Furthermore, it is possible to roll your own template to support a specific
- kind of material.
- Later we'll describe in more detail what is involved, and hopefully you
- will submit all the templates you create so we can include them in a later
- LyX version.
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-Another basic idea of the external material feature is to distinguish between
- the original file that serves as a base for final material and the produced
- file that is included in your exported or printed document.
- For example, consider the case of a figure produced with XFig.
- The XFig application itself works on an original file with the
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- extension.
- Within XFig, you create and change your figure, and when you are done,
- you save the
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--file.
- When you want to include the figure in your document, you invoke
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-transfig
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- in order to create a PostScript file that can readily be included in your
- LaTeX file.
- In this case, the
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- file is the original file, and the PostScript file is the produced file.
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-This distinction is important in order to allow updating of the material
- while you are in the process of writing the document.
- Furthermore, it provides us with the flexibility that is needed to support
- multiple export formats.
- For instance, in the case of an Ascii resulting file, it is not exactly
- an award-winning idea to include the figure as raw PostScript.
- Instead, you'd either prefer to just include a reference to the figure,
- or try to invoke some graphics to Ascii converter to make the final result
- look similar to the real graphics.
- The external material management allows you to do this, because it is parameter
-ized on the different export formats that LyX supports.
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-Besides supporting the production of different products according to the
- exported format, it supports tight integration with editing and viewing
- applications.
- In the case of an XFig figure, you are able to invoke
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- on the original file with a single click from within the external material
- dialog in LyX, and also preview the produced PostScript file with
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-ghostview
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- with another click.
- No more fiddling around with the command line and/or file browsers to locate
- and manipulate the original or produced files.
- In this way, you are finally able to take full advantage of the many different
- applications that are relevant to use when you write your documents, and
- ultimately be more productive.
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-So, all in all, LyX has information about a number of different programs
- to use behind the scenes in order to realize all of this machinery.
- This information, in fact, is exactly what is contained in the templates.
- To each template, there is associated a list of command lines that are
- used to invoke applications, convert the original file to the produced
- file, and more.
- This mechanism allows the advanced user to extend the capabilities of LyX
- without fiddling with the source code.
- It requires some footwork to define all the different commands and flags,
- but luckily, the LyX team did all the hard work and specified these for
- you.
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-But before the trees grow into the skies, we have to admit that we did take
- one tiny short-cut.
- Since you can produce many different kinds of files to go with each exported
- format, one could also expect that it would be possible to preview each
- product.
- The LyX team decided against this in order to keep the user interface simple.
- Instead of providing a button for each exported file format, we decided
- to introduce the concept of the primary file format and just have one button.
- When you press
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-
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-result
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- in the external material dialog, you will get a view of the produced file
- in the primary file format.
- And the primary file format is specified by your document class.
- For most document classes, the primary file format is LaTeX, but for the
- DocBook document classes, the primary file format is DocBook.
- So, when you view the produced file, keep in mind that it will only be
- a preview of what the main result will be.
- If you want to see how other exported formats turn out, you have to export
- them and preview them by hand.
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-The external material dialog
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-\begin_layout Standard
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-You insert external material from the
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-nsert
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- menu.
- When you do this, a button is inserted into your document, and the external
- material dialog is shown.
- This dialog allows you to describe exactly what material should be included,
- and also how it should be included.
- Furthermore, it provides access to the external applications to either
- view, edit or produce the material that is used in the resulting file.
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-At the top of this dialog, there is a drop-down list where you can chose
- which template should be used.
- Just below the template drop-down, there's a text area with a short blurb
- about the chosen template that should help you use it.
- Most often, it will provide a short description of the template, and a
- few hints on how to parameterize the use of it.
- Further down, you'll find a filename input field along with a
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-Browse
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- button that allows you to chose which file should be included with the
- standard file browser.
- Thus this field specifies the original file.
- Since the produced file is automatically generated when needed, there is
- no need to give access to it in the user interface.
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-At the bottom of the dialog, you'll find a general input box called
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-Parameters
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- This box is generally used to parameterize the specific template.
- The specific use should be covered in the help blurb associated with the
- template, but it typically allows you to define variations on how the produced
- file should be generated.
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-At the right side of the dialog, you'll find three buttons:
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-Edit
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