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Print_Tricks.tex
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fixing LATEX quotes and angle brackets.
1: \label{Print_Tricks}
2:
3: When you print a LON-CAPA resource, the XML of your resource is translated into
4: LaTeX. The LaTeX is then processed and turned into a PDF document which can
5: be displayed with your browser's Acrobat plugin and subsequently printed.
6:
7: There are several problems that crop up both due to limitations in the XML to LaTeX
8: translation and due to differences in the model used by web browsers to render
9: HTML and LaTeX to compose print pages. This document provides information
10: about some of these problems and, where possible, solutions, and tricks to work
11: around them. If you have a printing trick or a problem and would like to report
12: it, please go to http://bugs.lon-capa.org and register a bug report.
13:
14: General information about printing within LonCAPA is also available in section
15: \ref{Print_Resource}. Some types of problems that may occur include:
16:
17: \null
18: \noindent\textbf{The print rendition of some Perl functions looks ugly }
19:
20: In particular these functions are:
21: \begin{itemize}
22: \item \&prettyprint
23: \item \&dollarformat
24: \item \&xmlparse
25: \item \&chemparse
26: \end{itemize}
27:
28:
29: To make these two functions work correctly within the print translator, it is
30: necessary to wrap them within a \texttt{$<$display$>$} tag. For example:
31:
32: \begin{verbatim}
33: <p>
34: If I had <display>&prettyprint(100,'$2f')</display>
35: </p>
36: \end{verbatim}
37:
38: Note that the \texttt{<display>} tags must be tightly wrapped around the function call or
39: you will get a syntax error in web presentation mode. For additional information
40: about cases where you must use \texttt{<display>}, see ``Variables with tags don't print
41: correctly'' below.
42:
43: \null
44: \noindent\textbf{Image placement and alignment and text wrapping is wrong}
45:
46: Unfortunately this is due to a large difference between the LaTeX and HTML page
47: layout model. In HTML images are placed exactly where you ask them to be placed.
48: In LaTeX, images are considered {\em floats}, which LaTeX will place for you.
49: Some of the common html tricks, using tables e.g. to control text wrapping around
50: figures, will not always work in print mode; especially if the text is to the
51: right side of the figure in the table.
52:
53: The alignment choice
54: affects whether or not the print rendering engine attempts to get text to wrap around the
55: image. With \texttt{align="right"} or \texttt{align="left"}, the print rendering engine
56: attempts to use the {\em wrapfigure}
57: environment to place text around the figure at the
58: appropriate side. If a figure is in a table, then the print engine, by default,
59: the print engine will use wrapfigure, set the alignment to ``right''
60: unless you override it. Otherwise, the default alignment is ``bottom'' as it
61: is for html, and no wrapping will occur.
62:
63: \verb+\parpic+ style wrapping is also available by specifying \texttt{TeXwrap="parpic"}
64: in the \texttt{$<$img$>$} tag. In some limited casese this gives a better result.
65:
66:
67: Other print specific \texttt{$<$img$>$} tag attributes are available (see section \ref{Print_Options}).
68:
69: \null
70: \noindent\textbf{Variables with tags don't print correctly}
71:
72: If a variable contains XML, in general it is necessary to force the XML parser
73: to make a pass over the contents of the contents of the variable prior to rendering
74: the section of the resource that contains that substitution. When output,
75: those variables must be bracketed inside of \texttt{<display> </display>} tags.
76: For example:
77:
78: \begin{verbatim}
79: <problem>
80: <script type="loncapa/perl">
81: $a = &xmlparse('<br />');
82: </script>
83: <startouttext />
84: <p>This is a break <display>$a</display> and then some more text</p>
85: <endouttext />
86: </problem>
87: \end{verbatim}
88:
89: Without the xmlparse call and the display tag bracketing the variable, this
90: problem will display on the web just fine, but print incorrectly.
91:
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