Generate Call Graphs Using Doxygen in Emacs

Doxygen is a nice tool for generating documentations for well-annotated C/C++ projects, the one feature that I like most is generating call graphs and class diagrams, so that I can learn a project quickly by browsing the diagrams from a higher point of view.

I take the following steps to generate call graphs for a project on terminals on Linux:

cd /path/to/a/project/, and generate a template config file by doxygen -s -g doxygen.conf (Omit -s to generate it with detailed comments).

Tweak the file by specifying input and output directories, and set HAVE_DOT and CALL_GRAPH to YES.

Here is the complete diff:

--- doxygen.conf.orig
+++ doxygen.conf
@@ -8,7 +8,7 @@
 PROJECT_NUMBER         =
 PROJECT_BRIEF          =
 PROJECT_LOGO           =
-OUTPUT_DIRECTORY       =
+OUTPUT_DIRECTORY       = /path/to/doxygen-output/
 CREATE_SUBDIRS         = NO
 ALLOW_UNICODE_NAMES    = NO
 OUTPUT_LANGUAGE        = English
@@ -114,7 +114,7 @@
 #---------------------------------------------------------------------------
 # Configuration options related to the input files
 #---------------------------------------------------------------------------
-INPUT                  =
+INPUT                  = /path/to/a/project/ # the directory of the source code
 INPUT_ENCODING         = UTF-8
 FILE_PATTERNS          = *.c \
                          ,*.cc \
@@ -161,7 +161,7 @@
                          ,*.ucf \
                          ,*.qsf \
                          ,*.ice
-RECURSIVE              = NO
+RECURSIVE              = YES
 EXCLUDE                =
 EXCLUDE_SYMLINKS       = NO
 EXCLUDE_PATTERNS       =
@@ -255,7 +255,7 @@
 #---------------------------------------------------------------------------
 # Configuration options related to the LaTeX output
 #---------------------------------------------------------------------------
-GENERATE_LATEX         = YES
+GENERATE_LATEX         = NO
 LATEX_OUTPUT           = latex
 LATEX_CMD_NAME         =
 MAKEINDEX_CMD_NAME     = makeindex
@@ -345,10 +345,10 @@
 MSCGEN_PATH            =
 DIA_PATH               =
 HIDE_UNDOC_RELATIONS   = YES
-HAVE_DOT               = NO
+HAVE_DOT               = YES
 DOT_NUM_THREADS        = 0
 DOT_FONTNAME           = Helvetica
-DOT_FONTSIZE           = 10
+DOT_FONTSIZE           = 14
 DOT_FONTPATH           =
 CLASS_GRAPH            = YES
 COLLABORATION_GRAPH    = YES
@@ -358,7 +358,7 @@
 TEMPLATE_RELATIONS     = NO
 INCLUDE_GRAPH          = YES
 INCLUDED_BY_GRAPH      = YES
-CALL_GRAPH             = NO
+CALL_GRAPH             = YES
 CALLER_GRAPH           = NO
 GRAPHICAL_HIERARCHY    = YES
 DIRECTORY_GRAPH        = YES

Run doxygen doxygen.conf, that's it.

It's a bit boring to do this for every project, and let's improve the workflow a bit by using yasnippet and making a new Emacs command.

First, make a new config template snippet with 3 placeholders (Set yas-indent-line to avoid reindention by yasnippet):

# -*- mode: snippet -*-
# expand-env: ((yas-indent-line 'never))
# --
# Doxyfile 1.8.15

PROJECT_NAME           = "${1:my-cool-project}"
...
OUTPUT_DIRECTORY       = ${2:`(format "%s/doxygen/" (expand-file-name "~"))`$1}
...
INPUT                  = $3 # XXX must be an absolute path

With this snippet (see the exact file here), I can quickly create a doxygen config for a project by "finding" a new file and insert the snippet by M-x yas-insert-snippet.

Second, make a helper command to run doxygen quickly with a projects buffer as the current buffer of Emacs:

(defun w/run-doxygen ()
  "Run doxygen asynchronously."
  (interactive)
  (let ((conf (locate-dominating-file default-directory "doxygen.conf")))
    (if (not conf)
        (message "No doxygen.conf found!")
      (shell-command (format "doxygen %sdoxygen.conf&" conf)))))

This time, just type M-x w/run-doxygen to generate call graphs in Emacs.

Emacs

See also