chore(build): deploy doxygen documentation on master branch pushes

This commit enables travis to automatically build doxygen documentation
on updates to the master branch. The documentation is accessible from
the qTox website under the URL: https://qtox.github.io/doxygen

.travis.yml

@@ -17,3 +17,6 @@ deploy:
     repo: qTox/qTox
     tags: true
   skip_cleanup: true
+
+after_success:
+- test $TRAVIS_PULL_REQUEST == "false" && test $TRAVIS_BRANCH == "master" && bash ./.travis/build-docs.sh

.travis/build-docs.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+#
+#    Copyright © 2016 by The qTox Project
+#
+#    This program is libre software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+# Obtain doxygen
+sudo apt-get install doxygen
+
+CONFIG_FILE="doxygen.conf"
+CONFIG_FILE_TMP="$CONFIG_FILE.tmp.autogen"
+
+GIT_DESC=$(git describe --tags 2> /dev/null)
+GIT_CHASH=$(git rev-parse HEAD)
+
+# Create temporary config file
+cp "$CONFIG_FILE" "$CONFIG_FILE_TMP"
+
+# Append git version to doxygen version string
+echo "PROJECT_NUMBER = \"Version: $GIT_DESC | Commit: $GIT_CHASH\"" >> "$CONFIG_FILE_TMP"
+
+# Generate documentation
+echo "Generating documentation..."
+echo
+
+doxygen "$CONFIG_FILE_TMP"
+rm "$CONFIG_FILE_TMP"
+
+# Push generated doxygen to GitHub pages
+cd ./doc/html/
+
+git init
+git config user.name "Travis CI"
+git config user.email "qTox@users.noreply.github.com"
+
+git add .
+git commit -m "Deploy to GH pages from commit: $GIT_CHASH"
+
+echo "Pushing to GH pages..."
+git push --force --quiet "https://${GH_TOKEN}@github.com/qTox/doxygen.git" master:gh-pages &> /dev/null