1 Introduction

Does your neck hurt from turning between previewer windows and the source too often? This AUCTeX component will render your displayed LaTeX equations right into the editing window where they belong.

The purpose of preview-latex is to embed LaTeX environments such as display math or figures into the source buffers and switch conveniently between source and image representation.

1.1 What use is it?

WYSIWYG (what you see is what you get) sometimes is considered all the rage, sometimes frowned upon. Do we really want it? Wrong question. The right question is what we want from it. Except when finetuning the layout, we don’t want to use printer fonts for on-screen text editing. The low resolution and contrast of a computer screen render all but the coarsest printer fonts (those for low-quality newsprint) unappealing, and the margins and pagination of the print are not wanted on the screen, either. On the other hand, more complex visual compositions like math formulas and tables can’t easily be taken in when seen only in the source. preview-latex strikes a balance: it only uses graphic renditions of the output for certain, configurable constructs, does this only when told, and then right in the source code. Switching back and forth between the source and preview is easy and natural and can be done for each image independently. Behind the scenes of preview-latex, a sophisticated framework of other programs like ‘dvipng’, Dvips and Ghostscript are employed together with a special LaTeX style file for extracting the material of interest in the background and providing fast interactive response.

1.2 Activating preview-latex

After installation, the package may need to be activated (and remember to activate AUCTeX too). If preview-latex is installed via the Emacs package manager (ELPA), activation should be automatic upon installation.

The usual activation (if it is not done automatically) would be

(load "preview-latex.el" nil t t)

If you still don’t get a “Preview” menu in LaTeX mode in spite of AUCTeX showing its “Command”, your installation is broken. One possible cause are duplicate Lisp files that might be detectable with M-x list-load-path-shadows RET.

1.3 Getting started

Once activated, preview-latex and its documentation will be accessible via its menus (note that preview-latex requires AUCTeX to be loaded). When you have loaded a LaTeX document (a sample document circ.tex is included in the distribution, but most documents including math and/or figures should do), you can use its menu or C-c C-p C-d (for ‘Preview/Document’). Previews will now be generated for various objects in your document. You can use the time to take a short look at the other menu entries and key bindings in the ‘Preview’ menu. You’ll see the previewed objects change into a roadworks sign when preview-latex has determined just what it is going to preview. Note that you can freely navigate the buffer while this is going on. When the process is finished you will see the objects typeset in your buffer.

It is a bad idea, however, to edit the buffer before the roadworks signs appear, since that is the moment when the correlation between the original text and the buffer locations gets established. If the buffer changes before that point of time, the previews will not be placed where they belong. If you do want to change some obvious error you just spotted, we recommend you stop the background process by pressing C-c C-k.

To see/edit the LaTeX code for a specific object, put the point (the cursor) on it and press C-c C-p C-p (for ‘Preview/at point’). It will also do to click with the middle mouse button on the preview. Now you can edit the code, and generate a new preview by again pressing C-c C-p C-p (or by clicking with the middle mouse button on the icon before the edited text).

If you are using the desktop package, previews will remain from one session to the next as long as you don’t kill your buffer.

1.4 Basic modes of operation

preview-latex has a number of methods for generating its graphics. Its default operation is equivalent to using the ‘LaTeX’ command from AUCTeX. If this happens to be a call of PDFLaTeX generating PDF output (you need at least AUCTeX 11.51 for this), then Ghostscript will be called directly on the resulting PDF file. If a DVI file gets produced, first Dvips and then Ghostscript get called by default.

The image type to be generated by Ghostscript can be configured with

M-x customize-variable RET preview-image-type RET

The default is ‘png’ (the most efficient image type). A special setting is ‘dvipng’ in case you have the ‘dvipng’ program installed. In this case, ‘dvipng’ will be used for converting DVI files and Ghostscript (with a ‘PNG’ device) for converting PDF files. ‘dvipng’ is much faster than the combination of Dvips and Ghostscript. You can get downloads, access to its CVS archive and further information from its project site.

1.5 More documentation

After the installation, documentation in the form of an info manual will be available. You can access it with the standalone info reader with

info preview-latex

or by pressing C-h i d m preview-latex RET in Emacs. Once preview-latex is activated, you can instead use C-c C-p TAB (or the menu entry ‘Preview/Read documentation’).

Depending on your installation, a printable manual may also be available in the form of preview-latex.dvi or preview-latex.ps.

Detailed documentation for the LaTeX style used for extracting the preview images is placed in preview.dvi in a suitable directory during installation; on typical teTeX-based systems,

texdoc preview

will display it.

1.6 Availability

The preview-latex project is now part of AUCTeX and accessible as part of the AUCTeX project page. You can get its files from the AUCTeX download area. As of AUCTeX 11.81, preview-latex should already be integrated into AUCTeX, so no separate download will be necessary.

You will also find .rpm files there for Fedora and possibly SuSE. Anonymous Git is available as well.

1.7 Contacts

Bug reports should be sent by using M-x preview-report-bug RET, as this will fill in a lot of information interesting to us. If the installation fails (but this should be a rare event), report bugs to bug-auctex@gnu.org.

There is a general discussion list for AUCTeX which also covers preview-latex, look at https://lists.gnu.org/mailman/listinfo/auctex. For more information on the mailing list, send a message with just the word “help” as subject or body to auctex-request@gnu.org. For the developers, there is the auctex-devel@gnu.org list; it would probably make sense to direct feature requests and questions about internal details there. There is a low-volume read-only announcement list available to which you can subscribe by sending a mail with “subscribe” in the subject to info-auctex-request@gnu.org.

Offers to support further development will be appreciated. If you want to show your appreciation with a donation to the main developer, you can do so via PayPal to dak@gnu.org, and of course you can arrange for service contracts or for added functionality. Take a look at the TODO list for suggestions in that area.