5. Known problems

A number of issues are known concerning the interoperation with various other software. Some of the known problems can be solved by moving to newer versions of the problematic software or by simple patches.

If you find something not mentioned here, please send a bug report using M-x preview-report-bug <RET>, which will fill in a lot of information interesting to us and send it to the bug-auctex@gnu.org list. Please use the bug reporting commands if at all possible.

5.1 Problems with Ghostscript

Most of the problems encountered come from interaction with Ghostscript. It is a good idea to have a fairly recent version of Ghostscript installed. One problem occurs if you have specified the wrong executable under Windows: the command line version of Ghostscript is called ‘GSWIN32C.EXE’, not ‘GSWIN32.EXE’.

When Ghostscript fails, the necessary information and messages from Ghostscript go somewhere. If Ghostscript fails before starting to process images, you’ll find the information at the end of the process buffer you can see with C-c C-l. If Ghostscript fails while processing a particular image, this image will be tagged with clickable buttons for the error description and for the corresponding source file.

The default options configurable with

M-x customize-variable <RET> preview-gs-options <RET>

include the options ‘-dTextAlphaBits=4’ and ‘-dGraphicsAlphaBits=4’. These options have been reported to make Ghostscript 5.50 fail, but should work under Ghostscript 6.51 and later. If you are experiencing problems, it might help to customize them away. Of course, this also takes away the joy of antialiasing, so upgrading Ghostscript might not be the worst idea after all.

The device names have changed over time, so when using an old Ghostscript, you may have problems with the devices demanded by the customizable variable preview-image-creators. In that case, make sure they fit your version of Ghostscript, at least the entry corresponding to the current value of preview-image-type. While not being best in file size and image quality, setting preview-image-creators to jpeg should probably be one of the best bets for the purpose of checking basic operation, since that device name has not changed in quite some time. But JPEG is not intended for text, but for photographic images. On a more permanent time scale, the best choice is to use PNG and complain to your suppliers if either Emacs or Ghostscript fail to properly accommodate this format.

5.2 Font problems with Dvips

Some fonts have been reported to produce wrong characters with preview-latex. preview-latex calls Dvips by default with the option ‘-Pwww’ in order to get scalable fonts for nice results. If you are using antialiasing, however, the results might be sufficiently nice with bitmapped fonts, anyway. You might try ‘-Ppdf’ for another stab at scalable fonts, or other printer definitions. Use

M-x customize-variable <RET> preview-fast-dvips-command <RET>

and

M-x customize-variable <RET> preview-dvips-command <RET>

in order to customize this.

One particular problem is that several printer setup files (typically in a file called ‘/usr/share/texmf/dvips/config/config.pdf’ if you are using the ‘-Ppdf’ switch) contain the ‘G’ option for ‘character shifting’. This option will result in ‘fi’ being rendered as ‘£’ (British Pounds sign) in several fonts, unless your version of Dvips has a long-standing bug in its implementation fixed (only very recent versions of Dvips have).

5.3 Emacs problems

• GNU Emacs versions

  Don’t use Emacsen older than 21.3 on X11-based systems. On most other systems, you’ll need at least Emacs 22.1 or one of the developer versions leading up to it. Details can be found in (auctex)Prerequisites section ‘Prerequisites’ in the AUCTeX manual.

• Emacsen on Windows operating systems

  For Emacs 21, no image support is available in Emacs under Windows. Without images, preview-latex is useless. The current CVS version of Emacs available from http://savannah.gnu.org/projects/emacs now supports images including the PNG format, so Emacs 22 should work out of the box once it is released. Precompiled versions are available from http://crasseux.com/emacs and http://nqmacs.sf.net.

  For detailed installation instructions for Windows, see (auctex)Installation under MS Windows section ‘Installation under MS Windows’ in the AUCTeX manual.

• XEmacs

  There is are two larger problems known with older XEmacs releases. One leads to seriously mispositioned baselines and previews hanging far above other text on the same line. This should be fixed as of XEmacs-21.4.9.

  The other core bug causes a huge delay when XEmacs’s idea of the state of processes (like ghostscript) is wrong, and can lead to nasty spurious error messages. It should be fixed in version 21.4.8.

  Previews will only remain from one session to the next if you have version 1.81 or above of the ‘edit-utils’ package, first released in the 2002-03-12 sumo tarball.

5.4 Too small bounding boxes

The bounding box of a preview is determined by the LaTeX package using the pure TeX bounding boxes. If there is material extending outside of the TeX box, that material will be missing from the preview image. This happens for the label-showing boxes from the showkeys package. This particular problem can be circumvented by using the showlabels option of the preview package.

In general, you should try to fix the problem in the TeX code, like avoiding drawing outside of the picture with PSTricks.

One possible remedy is to set preview-fast-conversion to ‘Off’ (see section The Emacs interface). The conversion will take more time, but will then use the bounding boxes from EPS files generated by Dvips.

Dvips generally does not miss things, but it does not understand PostScript constructs like \resizebox or \rotate commands, so will generate rather wrong boxes for those. Dvips can be helped with the psfixbb package option to preview (see section The LaTeX style file), which will tag the corners of the included TeX box. This will mostly be convenient for pure PostScript stuff like that created by PSTricks, which Dvips would otherwise reserve no space for.

5.5 x-symbol interoperation

Thanks to the work of Christoph Wedler, starting with version ‘4.0h/beta’ of x-symbol, the line parsing of AUCTeX and preview-latex is fully supported. Earlier versions exhibit problems. However, versions before 4.2.2 will cause a drastic slowdown of preview-latex’s parsing pass, so we don’t recommend to use versions earlier than that.

If you wonder what x-symbol is, it is a package that transforms various tokens and subscripts to a more readable form while editing and offers a few input methods handy especially for dealing with math. Take a look at http://x-symbol.sourceforge.net.

x-symbol versions up to 4.5.1-beta at least require an 8bit-clean TeX implementation (meaning that its terminal output should not use ‘^^’-started escape sequences) for cooperation with preview-latex. Later versions may get along without it, like preview-latex does now.

If you experience problems with ‘circ.tex’ in connection with both x-symbol and Latin-1 characters, you may need to change your language environment or, as a last resort, customize the variable LaTeX-command-style by replacing the command latex with latex -translate-file=cp8bit.

5.6 Middle-clicks paste instead of toggling

This is probably the fault of your favorite package. ‘flyspell.el’ and ‘mouse-drag.el’ are known to be affected in versions before Emacs 21.3. Upgrade to the most recent version. What version of XEmacs might contain the fixes is unknown.

‘isearch.el’ also shows this effect while searches are in progress, but the code is such a complicated mess that no patch is in sight. Better just end the search with <RET> before toggling and resume with C-s C-s or similar afterwards. Since previews over the current match will auto-open, anyway, this should not be much of a problem in practice.

This document was generated on July 18, 2012 using texi2html 1.82.