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Annotation of loncom/html/adm/help/tex/Print_Tricks.tex, revision 1.6

1.1       foxr        1: \label{Print_Tricks}
                      2: 
1.3       felicia     3: When you print a LON-CAPA resource, the XML of your resource is translated into
1.1       foxr        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: 
                     15: \ref{Print_Resource}
                     16: 
1.5       foxr       17: \emph{The print rendition  of some Perl functions looks ugly }
                     18: 
                     19: In particular these functions are:
                     20: \begin{itemize}
                     21:    \item \&prettyprint
                     22:    \item \&dollarformat
                     23:    \item \&xmlparse
                     24:    \item \&chemparse
                     25: \end{itemize}
                     26: 
1.2       foxr       27: 
1.1       foxr       28: To make these two functions work correctly within the print translator, it is
1.3       felicia    29: necessary to wrap them within a <display> tag.  For example:
1.1       foxr       30: 
                     31: \begin{verbatim}
                     32: <p>
1.4       felicia    33: If I had <display>&prettyprint(100,'$2f')</display>
1.1       foxr       34: </p>
                     35: \end{verbatim}
                     36: 
1.4       felicia    37: Note that the \texttt{<display>} tags must be tightly wrapped around the function call or
1.5       foxr       38: you will get a syntax error in web presentation mode.  For additional information
                     39: about cases where you must use \texttt{<display>}, see ``Variables with tags don't print
                     40: correctly'' below.
1.1       foxr       41: 
                     42: 
1.5       foxr       43: \emph{Image placement and alignment and text wrapping is wrong}
1.2       foxr       44: 
1.1       foxr       45: Unfortunately this is due to a large difference between the LaTeX and HTML page
                     46: layout model.  In HTML images are placed exactly where you ask them to be placed.  
1.5       foxr       47: In LaTeX, images are considered {\em floats}, which LaTeX will place for you.  
                     48: Some of the common html tricks, using tables e.g. to control text wrapping around
                     49: figures, will not always work in print mode; especially if the text is to the
                     50: right side of the figure in the table.
                     51: 
                     52: The alignment choice 
                     53: affects whether or not the print rendering engine attempts to get text to wrap around the 
                     54: image.  With \texttt{align=``right''} or \texttt{align=``left''}, the print rendering engine
                     55: attempts to use the {\em wrapfigure} 
                     56: environment to place text around the figure at the
                     57: appropriate side.  If a figure is in a table, then the print engine, by default, 
                     58: the print engine will use wrapfigure, set the alignment to ``right'' 
                     59: unless you override it.  Otherwise, the default alignment is ``bottom'' as it 
                     60: is for html, and no wrapping will occur.  
                     61: 
1.6     ! albertel   62: \verb+\parpic+ style wrapping is also available by specifying \texttt{TeXwrap=``parpic''}
1.5       foxr       63:  in the <img> tag.  In some limited casese this gives a better result.
                     64: 
                     65: 
                     66: Other print specific <img> tag attributes are available. \ref{Print_Options}.
                     67: 
                     68: 
1.1       foxr       69: 
1.2       foxr       70: \emph{Variables with tags don't print correctly}
                     71: 
1.1       foxr       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
1.5       foxr       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:
1.1       foxr       77: 
                     78: \begin{verbatim}
1.2       foxr       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}
1.1       foxr       88: 
1.2       foxr       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.
1.1       foxr       91: 
                     92: 
                     93: