@node Point and click
@appendix Point and click
@cindex point and click


Point and click lets you find notes in the input by clicking on them
in the PDF viewer.  This makes it easier to find input that causes
some error in the sheet music.

When this functionality is active, LilyPond adds hyperlinks to the PDF
file. These hyperlinks are sent to the web-browser, which opens a
text-editor with the cursor in the right place.

To make this chain work, you should configure your PDF viewer to
follow hyperlinks using the @file{lilypond-invoke-editor} script
supplied with LilyPond.

For Xpdf on Unix, the following should be present in
@file{xpdfrc}@footnote{On unix, this file is found either in
@file{/etc/xpdfrc} or as @file{.xpdfrc} in your home directory.}

@example
urlCommand     "lilypond-invoke-editor %s"
@end example

The program @file{lilypond-invoke-editor} is a small helper
program. It will invoke an editor for the special @code{textedit}
URIs, and run a web browser for others.  It tests the environment
variable @code{EDITOR} for the following patterns,

@table @code
@item emacs
  this will invoke
@example
emacsclient --no-wait +@var{line}:@var{column} @var{file}
@end example
@item vim
  this will invoke
@example
gvim --remote +:@var{line}:norm@var{char} @var{file}
@end example

@item nedit
this will invoke
@example
  nc -noask +@var{line} @var{file}'
@end example
@end table

The environment variable @code{LYEDITOR} is used to override this. It
contains the command line to start the editor, where @code{%(file)s},
@code{%(column)s}, @code{%(line)s} is replaced with the file, column
and line respectively. The  setting

@example
emacsclient --no-wait +%(line)s:%(column)s %(file)s
@end example

@noindent
for @code{LYEDITOR} is equivalent to the standard emacsclient
invocation.


@cindex file size, output

The point and click links enlarge the output files significantly. For
reducing the size of PDF and PS files, point and click may be switched
off by issuing

@example
#(ly:set-option 'point-and-click #f)
@end example

@noindent
in a @file{.ly} file.  Alternately, you may pass this as an command-line
option

@example
lilypond -dno-point-and-click file.ly
@end example