Suppport for MSVC DLLs. Change-Id: Ibbcc4ba4e59f5bbf1cb91fe81c7d3b9042d03493

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6acedd5..6f56f3b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt

@@ -111,6 +111,17 @@
 IF (MSVC)
   OPTION(MSVC_USE_STATIC_CRT
     "MS Visual Studio: Use static C-Run Time Library in place of shared." OFF)
+
+  IF ( BUILD_TESTING AND BUILD_SHARED_LIBS)
+    MESSAGE(
+      "-- Disabling tests. The flags BUILD_TESTING and BUILD_SHARED_LIBS"
+      " are incompatible with MSVC."
+    )
+    # Retain the help string associated with the BUILD_TESTING option
+    # and turn testing off.
+    GET_PROPERTY(HELP_STRING CACHE BUILD_TESTING PROPERTY HELPSTRING)
+    SET(BUILD_TESTING OFF CACHE BOOL "${HELP_STRING}" FORCE)
+  ENDIF (BUILD_TESTING AND BUILD_SHARED_LIBS)
 ENDIF (MSVC)
 
 # Prior to October 2013, Ceres used some non-CMake standardised variables to
@@ -474,6 +485,7 @@
 
 IF (BUILD_SHARED_LIBS)
   MESSAGE("-- Building Ceres as a shared library.")
+  ADD_DEFINITIONS(-DCERES_BUILDING_SHARED_LIBRARY)
 ELSE (BUILD_SHARED_LIBS)
   MESSAGE("-- Building Ceres as a static library.")
 ENDIF (BUILD_SHARED_LIBS)

diff --git a/docs/source/building.rst b/docs/source/building.rst
index 700f41a..14ff68e 100644
--- a/docs/source/building.rst
+++ b/docs/source/building.rst

@@ -310,7 +310,9 @@
 
 #. The default build is Debug; consider switching it to release mode.
 #. Currently ``system_test`` is not working properly.
-#. Building Ceres as a DLL is not supported; patches welcome.
+#. If you build Ceres as a DLL with Visual Studio (BUILD_SHARED_LIBS),
+   you have to compile your own code with the flag
+   CERES_USING_SHARED_LIBRARY.
 #. CMake puts the resulting test binaries in ``ceres-bin/examples/Debug``
    by default.
 #. The solvers supported on Windows are ``DENSE_QR``, ``DENSE_SCHUR``,

diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 60e464d..eda929b 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt

@@ -28,6 +28,10 @@
 #
 # Author: keir@google.com (Keir Mierle)
 
+IF (BUILD_SHARED_LIBS)
+  ADD_DEFINITIONS(-DCERES_USING_SHARED_LIBRARY)
+ENDIF()
+
 ADD_EXECUTABLE(helloworld helloworld.cc)
 TARGET_LINK_LIBRARIES(helloworld ceres)
 

diff --git a/include/ceres/c_api.h b/include/ceres/c_api.h
index add68de..632542e 100644
--- a/include/ceres/c_api.h
+++ b/include/ceres/c_api.h

@@ -38,12 +38,14 @@
 #ifndef CERES_PUBLIC_C_API_H_
 #define CERES_PUBLIC_C_API_H_
 
+#include "ceres/internal/port.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /* Init the Ceres private data. Must be called before anything else. */
-void ceres_init();
+CERES_EXPORT void ceres_init();
 
 /* Equivalent to CostFunction::Evaluate() in the C++ API.
  *
@@ -88,23 +90,23 @@
  *
  * See loss_function.h for the details of each loss function.
  */
-void* ceres_create_huber_loss_function_data(double a);
-void* ceres_create_softl1_loss_function_data(double a);
-void* ceres_create_cauchy_loss_function_data(double a);
-void* ceres_create_arctan_loss_function_data(double a);
-void* ceres_create_tolerant_loss_function_data(double a, double b);
+CERES_EXPORT void* ceres_create_huber_loss_function_data(double a);
+CERES_EXPORT void* ceres_create_softl1_loss_function_data(double a);
+CERES_EXPORT void* ceres_create_cauchy_loss_function_data(double a);
+CERES_EXPORT void* ceres_create_arctan_loss_function_data(double a);
+CERES_EXPORT void* ceres_create_tolerant_loss_function_data(double a, double b);
 
 /* Free the given stock loss function data. */
-void ceres_free_stock_loss_function_data(void* loss_function_data);
+CERES_EXPORT void ceres_free_stock_loss_function_data(void* loss_function_data);
 
 /* This is an implementation of ceres_loss_function_t contained within Ceres
  * itself, intended as a way to access the various stock Ceres loss functions
  * from the C API. This should be passed to ceres_add_residual() below, in
  * combination with a user_data pointer generated by
  * ceres_create_stock_loss_function() above. */
-void ceres_stock_loss_function(void* user_data,
-                               double squared_norm,
-                               double out[3]);
+CERES_EXPORT void ceres_stock_loss_function(void* user_data,
+                                            double squared_norm,
+                                            double out[3]);
 
 /* Equivalent to Problem from the C++ API. */
 struct ceres_problem_s;
@@ -115,11 +117,11 @@
 
 /* Create and destroy a problem */
 /* TODO(keir): Add options for the problem. */
-ceres_problem_t* ceres_create_problem();
-void ceres_free_problem(ceres_problem_t* problem);
+CERES_EXPORT ceres_problem_t* ceres_create_problem();
+CERES_EXPORT void ceres_free_problem(ceres_problem_t* problem);
 
 /* Add a residual block. */
-ceres_residual_block_id_t* ceres_problem_add_residual_block(
+CERES_EXPORT ceres_residual_block_id_t* ceres_problem_add_residual_block(
     ceres_problem_t* problem,
     ceres_cost_function_t cost_function,
     void* cost_function_data,
@@ -130,7 +132,7 @@
     int* parameter_block_sizes,
     double** parameters);
 
-void ceres_solve(ceres_problem_t* problem);
+CERES_EXPORT void ceres_solve(ceres_problem_t* problem);
 
 /* TODO(keir): Figure out a way to pass a config in. */
 

diff --git a/include/ceres/conditioned_cost_function.h b/include/ceres/conditioned_cost_function.h
index 498d36e..2a12ba6 100644
--- a/include/ceres/conditioned_cost_function.h
+++ b/include/ceres/conditioned_cost_function.h

@@ -70,7 +70,7 @@
 //   ccf_residual[i] = f_i(my_cost_function_residual[i])
 //
 // and the Jacobian will be affected appropriately.
-class ConditionedCostFunction : public CostFunction {
+class CERES_EXPORT ConditionedCostFunction : public CostFunction {
  public:
   // Builds a cost function based on a wrapped cost function, and a
   // per-residual conditioner. Takes ownership of all of the wrapped cost

diff --git a/include/ceres/cost_function.h b/include/ceres/cost_function.h
index 722ac77..fee3e73 100644
--- a/include/ceres/cost_function.h
+++ b/include/ceres/cost_function.h

@@ -60,7 +60,7 @@
 // code inheriting from this class is expected to set these two members with the
 // corresponding accessors. This information will be verified by the Problem
 // when added with AddResidualBlock().
-class CostFunction {
+class CERES_EXPORT CostFunction {
  public:
   CostFunction() : num_residuals_(0) {}
 

diff --git a/include/ceres/covariance.h b/include/ceres/covariance.h
index 83126b5..b6e9a6a 100644
--- a/include/ceres/covariance.h
+++ b/include/ceres/covariance.h

@@ -196,9 +196,9 @@
 //  covariance.GetCovarianceBlock(y, y, covariance_yy)
 //  covariance.GetCovarianceBlock(x, y, covariance_xy)
 //
-class Covariance {
+class CERES_EXPORT Covariance {
  public:
-  struct Options {
+  struct CERES_EXPORT Options {
     Options()
 #ifndef CERES_NO_SUITESPARSE
         : algorithm_type(SPARSE_QR),

diff --git a/include/ceres/crs_matrix.h b/include/ceres/crs_matrix.h
index 8c470cd..687c958 100644
--- a/include/ceres/crs_matrix.h
+++ b/include/ceres/crs_matrix.h

@@ -38,7 +38,7 @@
 
 // A compressed row sparse matrix used primarily for communicating the
 // Jacobian matrix to the user.
-struct CRSMatrix {
+struct CERES_EXPORT CRSMatrix {
   CRSMatrix() : num_rows(0), num_cols(0) {}
 
   int num_rows;

diff --git a/include/ceres/internal/port.h b/include/ceres/internal/port.h
index e359d65..7bcb1a7 100644
--- a/include/ceres/internal/port.h
+++ b/include/ceres/internal/port.h

@@ -31,6 +31,9 @@
 #ifndef CERES_PUBLIC_INTERNAL_PORT_H_
 #define CERES_PUBLIC_INTERNAL_PORT_H_
 
+// This file needs to compile as c code.
+#ifdef __cplusplus
+
 #include <string>
 
 #if defined(CERES_TR1_MEMORY_HEADER)
@@ -59,4 +62,16 @@
 
 }  // namespace ceres
 
+#endif  // __cplusplus
+
+// A macro to signal wich functions and classes are exported when
+// bulding a DLL with MSC.
+#if defined(_MSC_VER) && defined(CERES_USING_SHARED_LIBRARY)
+# define CERES_EXPORT __declspec(dllimport)
+#elif defined(_MSC_VER) && defined(CERES_BUILDING_SHARED_LIBRARY)
+# define CERES_EXPORT __declspec(dllexport)
+#else
+# define CERES_EXPORT
+#endif
+
 #endif  // CERES_PUBLIC_INTERNAL_PORT_H_

diff --git a/include/ceres/iteration_callback.h b/include/ceres/iteration_callback.h
index 5689256..5eca392 100644
--- a/include/ceres/iteration_callback.h
+++ b/include/ceres/iteration_callback.h

@@ -41,7 +41,7 @@
 
 // This struct describes the state of the optimizer after each
 // iteration of the minimization.
-struct IterationSummary {
+struct CERES_EXPORT IterationSummary {
   IterationSummary()
       : iteration(0),
         step_is_valid(false),
@@ -211,7 +211,7 @@
 //     const bool log_to_stdout_;
 //   };
 //
-class IterationCallback {
+class CERES_EXPORT IterationCallback {
  public:
   virtual ~IterationCallback() {}
   virtual CallbackReturnType operator()(const IterationSummary& summary) = 0;

diff --git a/include/ceres/local_parameterization.h b/include/ceres/local_parameterization.h
index c0f7dc7..3ecd959 100644
--- a/include/ceres/local_parameterization.h
+++ b/include/ceres/local_parameterization.h

@@ -107,7 +107,7 @@
 //
 // The class LocalParameterization defines the function Plus and its
 // Jacobian which is needed to compute the Jacobian of f w.r.t delta.
-class LocalParameterization {
+class CERES_EXPORT LocalParameterization {
  public:
   virtual ~LocalParameterization() {}
 
@@ -133,7 +133,7 @@
 // Some basic parameterizations
 
 // Identity Parameterization: Plus(x, delta) = x + delta
-class IdentityParameterization : public LocalParameterization {
+class CERES_EXPORT IdentityParameterization : public LocalParameterization {
  public:
   explicit IdentityParameterization(int size);
   virtual ~IdentityParameterization() {}
@@ -150,7 +150,7 @@
 };
 
 // Hold a subset of the parameters inside a parameter block constant.
-class SubsetParameterization : public LocalParameterization {
+class CERES_EXPORT SubsetParameterization : public LocalParameterization {
  public:
   explicit SubsetParameterization(int size,
                                   const vector<int>& constant_parameters);
@@ -172,7 +172,7 @@
 // with * being the quaternion multiplication operator. Here we assume
 // that the first element of the quaternion vector is the real (cos
 // theta) part.
-class QuaternionParameterization : public LocalParameterization {
+class CERES_EXPORT QuaternionParameterization : public LocalParameterization {
  public:
   virtual ~QuaternionParameterization() {}
   virtual bool Plus(const double* x,

diff --git a/include/ceres/loss_function.h b/include/ceres/loss_function.h
index b99c184..5b6bf68 100644
--- a/include/ceres/loss_function.h
+++ b/include/ceres/loss_function.h

@@ -82,7 +82,7 @@
 
 namespace ceres {
 
-class LossFunction {
+class CERES_EXPORT LossFunction {
  public:
   virtual ~LossFunction() {}
 
@@ -128,7 +128,7 @@
 // It is not normally necessary to use this, as passing NULL for the
 // loss function when building the problem accomplishes the same
 // thing.
-class TrivialLoss : public LossFunction {
+class CERES_EXPORT TrivialLoss : public LossFunction {
  public:
   virtual void Evaluate(double, double*) const;
 };
@@ -171,7 +171,7 @@
 //
 // The scaling parameter 'a' corresponds to 'delta' on this page:
 //   http://en.wikipedia.org/wiki/Huber_Loss_Function
-class HuberLoss : public LossFunction {
+class CERES_EXPORT HuberLoss : public LossFunction {
  public:
   explicit HuberLoss(double a) : a_(a), b_(a * a) { }
   virtual void Evaluate(double, double*) const;
@@ -187,7 +187,7 @@
 //   rho(s) = 2 (sqrt(1 + s) - 1).
 //
 // At s = 0: rho = [0, 1, -1/2].
-class SoftLOneLoss : public LossFunction {
+class CERES_EXPORT SoftLOneLoss : public LossFunction {
  public:
   explicit SoftLOneLoss(double a) : b_(a * a), c_(1 / b_) { }
   virtual void Evaluate(double, double*) const;
@@ -204,7 +204,7 @@
 //   rho(s) = log(1 + s).
 //
 // At s = 0: rho = [0, 1, -1].
-class CauchyLoss : public LossFunction {
+class CERES_EXPORT CauchyLoss : public LossFunction {
  public:
   explicit CauchyLoss(double a) : b_(a * a), c_(1 / b_) { }
   virtual void Evaluate(double, double*) const;
@@ -225,7 +225,7 @@
 //   rho(s) = a atan(s / a).
 //
 // At s = 0: rho = [0, 1, 0].
-class ArctanLoss : public LossFunction {
+class CERES_EXPORT ArctanLoss : public LossFunction {
  public:
   explicit ArctanLoss(double a) : a_(a), b_(1 / (a * a)) { }
   virtual void Evaluate(double, double*) const;
@@ -264,7 +264,7 @@
 // concentrated in the range a - b to a + b.
 //
 // At s = 0: rho = [0, ~0, ~0].
-class TolerantLoss : public LossFunction {
+class CERES_EXPORT TolerantLoss : public LossFunction {
  public:
   explicit TolerantLoss(double a, double b);
   virtual void Evaluate(double, double*) const;
@@ -305,7 +305,7 @@
 // function, rho = NULL is a valid input and will result in the input
 // being scaled by a. This provides a simple way of implementing a
 // scaled ResidualBlock.
-class ScaledLoss : public LossFunction {
+class CERES_EXPORT ScaledLoss : public LossFunction {
  public:
   // Constructs a ScaledLoss wrapping another loss function. Takes
   // ownership of the wrapped loss function or not depending on the
@@ -362,7 +362,7 @@
 //
 //  Solve(options, &problem, &summary)
 //
-class LossFunctionWrapper : public LossFunction {
+class CERES_EXPORT LossFunctionWrapper : public LossFunction {
  public:
   LossFunctionWrapper(LossFunction* rho, Ownership ownership)
       : rho_(rho), ownership_(ownership) {

diff --git a/include/ceres/normal_prior.h b/include/ceres/normal_prior.h
index 480a074..530e652 100644
--- a/include/ceres/normal_prior.h
+++ b/include/ceres/normal_prior.h

@@ -56,7 +56,7 @@
 // which would be the case if the covariance matrix S is rank
 // deficient.
 
-class NormalPrior: public CostFunction {
+class CERES_EXPORT NormalPrior: public CostFunction {
  public:
   // Check that the number of rows in the vector b are the same as the
   // number of columns in the matrix A, crash otherwise.

diff --git a/include/ceres/problem.h b/include/ceres/problem.h
index b8759eb..5881677 100644
--- a/include/ceres/problem.h
+++ b/include/ceres/problem.h

@@ -117,9 +117,9 @@
 //   problem.AddResidualBlock(new MyBinaryCostFunction(...), x2, x3);
 //
 // Please see cost_function.h for details of the CostFunction object.
-class Problem {
+class CERES_EXPORT Problem {
  public:
-  struct Options {
+  struct CERES_EXPORT Options {
     Options()
         : cost_function_ownership(TAKE_OWNERSHIP),
           loss_function_ownership(TAKE_OWNERSHIP),

diff --git a/include/ceres/solver.h b/include/ceres/solver.h
index 3d63951..4fb6e4d 100644
--- a/include/ceres/solver.h
+++ b/include/ceres/solver.h

@@ -46,7 +46,7 @@
 class Problem;
 
 // Interface for non-linear least squares solvers.
-class Solver {
+class CERES_EXPORT Solver {
  public:
   virtual ~Solver();
 
@@ -55,7 +55,7 @@
   // problems; however, better performance is often obtainable with tweaking.
   //
   // The constants are defined inside types.h
-  struct Options {
+  struct CERES_EXPORT Options {
     // Default constructor that sets up a generic sparse problem.
     Options() {
       minimizer_type = TRUST_REGION;
@@ -713,7 +713,7 @@
     string solver_log;
   };
 
-  struct Summary {
+  struct CERES_EXPORT Summary {
     Summary();
 
     // A brief one line description of the state of the solver after
@@ -951,7 +951,7 @@
 };
 
 // Helper function which avoids going through the interface.
-void Solve(const Solver::Options& options,
+CERES_EXPORT void Solve(const Solver::Options& options,
            Problem* problem,
            Solver::Summary* summary);
 

diff --git a/include/ceres/types.h b/include/ceres/types.h
index e3dac3c..47bdb4c 100644
--- a/include/ceres/types.h
+++ b/include/ceres/types.h

@@ -402,69 +402,69 @@
   SPARSE_QR
 };
 
-const char* LinearSolverTypeToString(LinearSolverType type);
-bool StringToLinearSolverType(string value, LinearSolverType* type);
+CERES_EXPORT const char* LinearSolverTypeToString(LinearSolverType type);
+CERES_EXPORT bool StringToLinearSolverType(string value, LinearSolverType* type);
 
-const char* PreconditionerTypeToString(PreconditionerType type);
-bool StringToPreconditionerType(string value, PreconditionerType* type);
+CERES_EXPORT const char* PreconditionerTypeToString(PreconditionerType type);
+CERES_EXPORT bool StringToPreconditionerType(string value, PreconditionerType* type);
 
-const char* VisibilityClusteringTypeToString(VisibilityClusteringType type);
-bool StringToVisibilityClusteringType(string value,
+CERES_EXPORT const char* VisibilityClusteringTypeToString(VisibilityClusteringType type);
+CERES_EXPORT bool StringToVisibilityClusteringType(string value,
                                       VisibilityClusteringType* type);
 
-const char* SparseLinearAlgebraLibraryTypeToString(
+CERES_EXPORT const char* SparseLinearAlgebraLibraryTypeToString(
     SparseLinearAlgebraLibraryType type);
-bool StringToSparseLinearAlgebraLibraryType(
+CERES_EXPORT bool StringToSparseLinearAlgebraLibraryType(
     string value,
     SparseLinearAlgebraLibraryType* type);
 
-const char* DenseLinearAlgebraLibraryTypeToString(
+CERES_EXPORT const char* DenseLinearAlgebraLibraryTypeToString(
     DenseLinearAlgebraLibraryType type);
-bool StringToDenseLinearAlgebraLibraryType(
+CERES_EXPORT bool StringToDenseLinearAlgebraLibraryType(
     string value,
     DenseLinearAlgebraLibraryType* type);
 
-const char* TrustRegionStrategyTypeToString(TrustRegionStrategyType type);
-bool StringToTrustRegionStrategyType(string value,
+CERES_EXPORT const char* TrustRegionStrategyTypeToString(TrustRegionStrategyType type);
+CERES_EXPORT bool StringToTrustRegionStrategyType(string value,
                                      TrustRegionStrategyType* type);
 
-const char* DoglegTypeToString(DoglegType type);
-bool StringToDoglegType(string value, DoglegType* type);
+CERES_EXPORT const char* DoglegTypeToString(DoglegType type);
+CERES_EXPORT bool StringToDoglegType(string value, DoglegType* type);
 
-const char* MinimizerTypeToString(MinimizerType type);
-bool StringToMinimizerType(string value, MinimizerType* type);
+CERES_EXPORT const char* MinimizerTypeToString(MinimizerType type);
+CERES_EXPORT bool StringToMinimizerType(string value, MinimizerType* type);
 
-const char* LineSearchDirectionTypeToString(LineSearchDirectionType type);
-bool StringToLineSearchDirectionType(string value,
+CERES_EXPORT const char* LineSearchDirectionTypeToString(LineSearchDirectionType type);
+CERES_EXPORT bool StringToLineSearchDirectionType(string value,
                                      LineSearchDirectionType* type);
 
-const char* LineSearchTypeToString(LineSearchType type);
-bool StringToLineSearchType(string value, LineSearchType* type);
+CERES_EXPORT const char* LineSearchTypeToString(LineSearchType type);
+CERES_EXPORT bool StringToLineSearchType(string value, LineSearchType* type);
 
-const char* NonlinearConjugateGradientTypeToString(
+CERES_EXPORT const char* NonlinearConjugateGradientTypeToString(
     NonlinearConjugateGradientType type);
-bool StringToNonlinearConjugateGradientType(
+CERES_EXPORT bool StringToNonlinearConjugateGradientType(
     string value,
     NonlinearConjugateGradientType* type);
 
-const char* LineSearchInterpolationTypeToString(
+CERES_EXPORT const char* LineSearchInterpolationTypeToString(
     LineSearchInterpolationType type);
-bool StringToLineSearchInterpolationType(
+CERES_EXPORT bool StringToLineSearchInterpolationType(
     string value,
     LineSearchInterpolationType* type);
 
-const char* CovarianceAlgorithmTypeToString(
+CERES_EXPORT const char* CovarianceAlgorithmTypeToString(
     CovarianceAlgorithmType type);
-bool StringToCovarianceAlgorithmType(
+CERES_EXPORT bool StringToCovarianceAlgorithmType(
     string value,
     CovarianceAlgorithmType* type);
 
-const char* TerminationTypeToString(TerminationType type);
+CERES_EXPORT const char* TerminationTypeToString(TerminationType type);
 
-bool IsSchurType(LinearSolverType type);
-bool IsSparseLinearAlgebraLibraryTypeAvailable(
+CERES_EXPORT bool IsSchurType(LinearSolverType type);
+CERES_EXPORT bool IsSparseLinearAlgebraLibraryTypeAvailable(
     SparseLinearAlgebraLibraryType type);
-bool IsDenseLinearAlgebraLibraryTypeAvailable(
+CERES_EXPORT bool IsDenseLinearAlgebraLibraryTypeAvailable(
     DenseLinearAlgebraLibraryType type);
 
 }  // namespace ceres

diff --git a/internal/ceres/CMakeLists.txt b/internal/ceres/CMakeLists.txt
index a9ec1c2..b959768 100644
--- a/internal/ceres/CMakeLists.txt
+++ b/internal/ceres/CMakeLists.txt

@@ -137,7 +137,7 @@
 # Primarily for Android, but optionally for others, use the minimal internal
 # Glog implementation.
 IF (MINIGLOG)
-  ADD_LIBRARY(miniglog miniglog/glog/logging.cc)
+  ADD_LIBRARY(miniglog STATIC miniglog/glog/logging.cc)
   INSTALL(TARGETS miniglog
           EXPORT  CeresExport
           RUNTIME DESTINATION bin