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4.2.1 Starting Viewers

Viewers are normally invoked by pressing C-c C-c once the document is formatted, which will propose the View command, or by activating the respective entry in the Command menu. Alternatively you can type C-c C-v which calls the function TeX-view.

command TeX-view​

(C-c C-v) Start a viewer without confirmation. The viewer is started either on a region or the master file, depending on the last command issued. This is especially useful for jumping to the location corresponding to point in the viewer when using TeX-source-correlate-mode.

AUCTeX will try to guess which type of viewer (DVI, PostScript or PDF) has to be used and what options are to be passed over to it. This decision is based on the output files present in the working directory as well as the class and style options used in the document. For example, if there is a DVI file in your working directory, a DVI viewer will be invoked. In case of a PDF file it will be a PDF viewer. If you specified a special paper format like ‘a5paper’ or use the ‘landscape’ option, this will be passed to the viewer by the appropriate options. Especially some DVI viewers depend on this kind of information in order to display your document correctly. In case you are using ‘pstricks’ or ‘psfrag’ in your document, a DVI viewer cannot display the contents correctly and a PostScript viewer will be invoked instead.

The association between the tests for the conditions mentioned above and the viewers is made in the variable TeX-view-program-selection. Therefore this variable is the starting point for customization if you want to use other viewers than the ones suggested by default.

user option TeX-view-program-selection​

This is a list of predicates and viewers which is evaluated from front to back in order to find out which viewer to call under the given conditions. In the first element of each list item you can reference one or more predicates defined in TeX-view-predicate-list or TeX-view-predicate-list-builtin. In the second element you can reference a viewer defined in TeX-view-program-list or TeX-view-program-list-builtin. The viewer of the first item with a positively evaluated predicate is selected.

So TeX-view-program-selection only contains references to the actual implementations of predicates and viewer commands respectively which can be found elsewhere. AUCTeX comes with a set of preconfigured predicates and viewer commands which are stored in the variables TeX-view-predicate-list-builtin and TeX-view-program-list-builtin respectively. If you are not satisfied with those and want to overwrite one of them or add your own definitions, you can do so via the variables TeX-view-predicate-list and TeX-view-program-list.

user option TeX-view-predicate-list​

This is a list of predicates for viewer selection and invocation. The first element of each list item is a symbol and the second element a Lisp form to be evaluated. The form should return nil if the predicate is not fulfilled.

A built-in predicate from TeX-view-predicate-list-builtin can be overwritten by defining a new predicate with the same symbol.

user option TeX-view-program-list​

This is a list of viewer specifications each consisting of a symbolic name and either a command line or a function to be invoked when the viewer is called. If a command line is used, parts of it can be conditionalized by prefixing them with predicates from TeX-view-predicate-list or TeX-view-predicate-list-builtin. (See the doc string for the exact format to use.) The command line can also contain placeholders as defined in TeX-expand-list and TeX-expand-list-builtin which are expanded before the viewer is called.

The third element of each item is a string, or a list of strings, with the name of the executable, or executables, needed to open the output file in the viewer. Placeholders defined in TeX-expand-list and TeX-expand-list-builtin can be used here. This element is optional and is used to check whether the viewer is actually available on the system.

A built-in viewer spec from TeX-view-program-list-builtin can be overwritten by defining a new viewer spec with the same name.

After the viewer is called via either the View command or the key stroke C-c C-v, the window system focus goes and stays on the viewer. If you prefer that the focus is pulled back to Emacs immediately after that and you are using evince-compatible viewer, customize the option TeX-view-enince-keep-focus.

user option TeX-view-evince-keep-focus​

When this option is non-nil and the viewer is compatible with evince, the focus is pulled back to Emacs immediately after the viewer is invoked or refreshed from within AUCTeX.

Note that the viewer selection and invocation as described above will only work if certain default settings in AUCTeX are intact. For one, the whole viewer selection machinery will only be triggered if there is no ‘%V’ expander in TeX-expand-list. So if you have trouble with the viewer invocation you might check if there is an older customization of the variable in place. In addition, the use of a function in TeX-view-program-list only works if the View command in TeX-command-list makes use of the hook TeX-run-discard-or-function.

Note also that the implementation described above replaces an older one which was less flexible. This old implementation works with the variables TeX-output-view-style and TeX-view-style which are used to associate file types and style options with viewers. If desired you can reactivate it by using the placeholder ‘%vv’ for the View command in TeX-command-list. Note however, that it is bound to be removed from AUCTeX once the new implementation proved to be satisfactory. For the time being, find a short description of the mentioned customization options below.

user option TeX-output-view-style​

List of output file extensions, style options and view options. Each item of the list consists of three elements. If the first element (a regular expression) matches the output file extension, and the second element (a regular expression) matches the name of one of the style options, any occurrence of the string %V in a command in TeX-command-list will be replaced with the third element.

user option TeX-view-style​

List of style options and view options. This is the predecessor of TeX-output-view-style which does not provide the possibility to specify output file extensions. It is used as a fallback in case none of the alternatives specified in TeX-output-view-style match. In case none of the entries in TeX-view-style match either, no suggestion for a viewer is made.