Add Travis CI support.

- Currently builds for Linux (GCC), Android (r17b), macOS and iOS
  (Xcode 9.4).

Change-Id: I17f9adb90c12bff983c851cdcb20db1f9efce6fb

.travis.yml

diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..d159316
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,70 @@
+language: cpp
+
+matrix:
+  fast_finish: true
+  include:
+  - os: linux
+    dist: trusty
+    sudo: required
+    compiler: gcc
+    env: CERES_BUILD_TARGET=LINUX
+  - os: linux
+    dist: trusty
+    sudo: required
+    compiler: gcc
+    env: CERES_BUILD_TARGET=ANDROID
+  - os: osx
+    osx_image: xcode9.4
+    env: CERES_BUILD_TARGET=OSX
+  - os: osx
+    osx_image: xcode9.4
+    env: CERES_BUILD_TARGET=IOS
+
+env:
+  # As per http://docs.travis-ci.com/user/languages/cpp/#OpenMP-projects don't be greedy with OpenMP.
+  - OMP_NUM_THREADS=4
+
+before_install:
+  - if [ $TRAVIS_OS_NAME = linux ]; then sudo apt-get update -qq; fi
+  - |
+    if [[ "$CERES_BUILD_TARGET" == "ANDROID" ]]; then
+      cd /tmp
+      wget https://dl.google.com/android/repository/android-ndk-r17b-linux-x86_64.zip
+      unzip -qq android-ndk-r17b-linux-x86_64.zip
+    fi
+
+install:
+  - if [ $TRAVIS_OS_NAME = linux ]; then $TRAVIS_BUILD_DIR/travis/install_travis_linux_deps.sh; fi
+  - if [ $TRAVIS_OS_NAME = osx ]; then $TRAVIS_BUILD_DIR/travis/install_travis_osx_deps.sh; fi
+
+before_script:
+  - mkdir /tmp/ceres-build
+  - cd /tmp/ceres-build
+
+script:
+  # NOTE: TRAVIS_BUILD_DIR is actually the source directory for Ceres.
+  - |
+    if [[ "$CERES_BUILD_TARGET" == "LINUX" || "$CERES_BUILD_TARGET" == "OSX" ]]; then
+      cmake $TRAVIS_BUILD_DIR
+    fi
+  - |
+    if [[ "$CERES_BUILD_TARGET" == "ANDROID" ]]; then
+      cmake -DCMAKE_TOOLCHAIN_FILE=/tmp/android-ndk-r17b/build/cmake/android.toolchain.cmake -DEIGEN_INCLUDE_DIR=/usr/local/include/eigen3 -DANDROID_ABI=armeabi-v7a -DANDROID_STL=c++_shared -DANDROID_NATIVE_API_LEVEL=android-24 -DMINIGLOG=ON -DBUILD_EXAMPLES=OFF $TRAVIS_BUILD_DIR
+    fi
+  - |
+    if [[ "$CERES_BUILD_TARGET" == "IOS" ]]; then
+      cmake -DCMAKE_TOOLCHAIN_FILE=$TRAVIS_BUILD_DIR/cmake/iOS.cmake -DEIGEN_INCLUDE_DIR=/usr/local/include/eigen3 -DIOS_PLATFORM=OS $TRAVIS_BUILD_DIR
+    fi
+  - make -j 4
+  - |
+    if [[ "$CERES_BUILD_TARGET" == "LINUX" || "$CERES_BUILD_TARGET" == "OSX" ]]; then
+      sudo make install
+      ctest --output-on-failure -j 4
+    fi
+
+notifications:
+  email:
+    - alexs.mac@gmail.com
+    - sandwichmaker@gmail.com
+    - keir@google.com
+    - wjr@google.com

README.md

diff --git a/README.md b/README.md
index 3f8dbe1..ca076b8 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,8 @@
 Please see [ceres-solver.org](http://ceres-solver.org/) for more
 information.
 
+[![Build Status](https://travis-ci.org/ceres-solver/ceres-solver.svg?branch=master)](https://travis-ci.org/ceres-solver/ceres-solver)
+
 WARNING - Do not make GitHub pull requests!
 -------------------------------------------
 

travis/install_travis_linux_deps.sh

diff --git a/travis/install_travis_linux_deps.sh b/travis/install_travis_linux_deps.sh
new file mode 100755
index 0000000..581cb4a
--- /dev/null
+++ b/travis/install_travis_linux_deps.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+# Stop processing on any error.
+set -e
+
+# Install default versions of standard dependencies that are new enough in 14.04.
+sudo apt-get install -y cmake
+sudo apt-get install -y libatlas-base-dev libsuitesparse-dev
+sudo apt-get install -y libgoogle-glog-dev libgflags-dev
+
+# Install Eigen 3.3.4 as the default 14.04 version is 3.2.0 in which the sparse solvers
+# have known poor performance.
+wget http://bitbucket.org/eigen/eigen/get/3.3.4.tar.gz -O /tmp/eigen-3.3.4.tar.gz
+tar -C /tmp -xzf /tmp/eigen-3.3.4.tar.gz
+rm /tmp/eigen-3.3.4.tar.gz
+# Fix detection of BLAS/LAPACK broken in 3.3.4 release.
+wget https://bitbucket.org/eigen/eigen/commits/dbab66d00651bf050d1426334a39b627abe7216e/raw -O /tmp/eigen-3.3.4.fortran.patch
+cd /tmp/eigen-eigen-5a0156e40feb && patch -p1 < /tmp/eigen-3.3.4.fortran.patch
+mkdir /tmp/eigen-3.3.4-build
+cd /tmp/eigen-3.3.4-build
+cmake /tmp/eigen-eigen-5a0156e40feb && make && sudo make install

travis/install_travis_osx_deps.sh

diff --git a/travis/install_travis_osx_deps.sh b/travis/install_travis_osx_deps.sh
new file mode 100755
index 0000000..076eb71
--- /dev/null
+++ b/travis/install_travis_osx_deps.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+# Stop processing on any error.
+set -e
+
+brew install cmake glog gflags eigen suite-sparse