From aa56a1e38594e7da4f57d38c11818adeaeefd367 Mon Sep 17 00:00:00 2001
From: Lewis Liu <wei.zhi.liu@intel.com>
Date: Wed, 8 Apr 2020 15:19:28 +0800
Subject: [PATCH 1/2] add opencv4 into the dependency list.

Signed-off-by: Lewis Liu <wei.zhi.liu@intel.com>
---
 cv_bridge/CMakeLists.txt         |  2 +-
 cv_bridge/src/CMakeLists.txt     | 10 +++++++---
 cv_bridge/src/module_opencv3.cpp |  9 +++++++--
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/cv_bridge/CMakeLists.txt b/cv_bridge/CMakeLists.txt
index ed9f023e7..01d284668 100644
--- a/cv_bridge/CMakeLists.txt
+++ b/cv_bridge/CMakeLists.txt
@@ -37,7 +37,7 @@ else()
 endif()
 
 find_package(sensor_msgs REQUIRED)
-find_package(OpenCV 3 REQUIRED
+find_package(OpenCV 4 REQUIRED
   COMPONENTS
     opencv_core
     opencv_imgproc
diff --git a/cv_bridge/src/CMakeLists.txt b/cv_bridge/src/CMakeLists.txt
index 39db925d7..9e2cf45e3 100644
--- a/cv_bridge/src/CMakeLists.txt
+++ b/cv_bridge/src/CMakeLists.txt
@@ -44,10 +44,14 @@ if(PYTHON_VERSION_MAJOR VERSION_EQUAL 3)
   add_definitions(-DPYTHON3)
 endif()
 
-if(OpenCV_VERSION_MAJOR VERSION_EQUAL 3)
-  add_library(${PROJECT_NAME}_boost module.cpp module_opencv3.cpp)
-else()
+if(OpenCV_VERSION_MAJOR VERSION_EQUAL 4)
+  add_definitions(-DOPENCV_VERSION_4)
+endif()
+
+if(OpenCV_VERSION_MAJOR VERSION_LESS 3)
   add_library(${PROJECT_NAME}_boost module.cpp module_opencv2.cpp)
+else()
+  add_library(${PROJECT_NAME}_boost module.cpp module_opencv3.cpp)
 endif()
 target_link_libraries(${PROJECT_NAME}_boost
   ${PYTHON_LIBRARIES}
diff --git a/cv_bridge/src/module_opencv3.cpp b/cv_bridge/src/module_opencv3.cpp
index 2aa56021f..ac93f0897 100644
--- a/cv_bridge/src/module_opencv3.cpp
+++ b/cv_bridge/src/module_opencv3.cpp
@@ -99,6 +99,11 @@ class NumpyAllocator : public MatAllocator
   NumpyAllocator() {stdAllocator = Mat::getStdAllocator();}
   ~NumpyAllocator() {}
 
+// To compile openCV3 with OpenCV4 APIs.
+#ifndef OPENCV_VERSION_4
+#define AccessFlag int
+#endif
+
   UMatData * allocate(PyObject * o, int dims, const int * sizes, int type, size_t * step) const
   {
     UMatData * u = new UMatData(this);
@@ -115,7 +120,7 @@ class NumpyAllocator : public MatAllocator
   }
 
   UMatData * allocate(
-    int dims0, const int * sizes, int type, void * data, size_t * step, int flags,
+    int dims0, const int * sizes, int type, void * data, size_t * step, AccessFlag flags,
     UMatUsageFlags usageFlags) const
   {
     if (data != 0) {
@@ -148,7 +153,7 @@ class NumpyAllocator : public MatAllocator
     return allocate(o, dims0, sizes, type, step);
   }
 
-  bool allocate(UMatData * u, int accessFlags, UMatUsageFlags usageFlags) const
+  bool allocate(UMatData * u, AccessFlag accessFlags, UMatUsageFlags usageFlags) const
   {
     return stdAllocator->allocate(u, accessFlags, usageFlags);
   }

From e8c1d37ec62c526b3f67f22c6be499baa31ea294 Mon Sep 17 00:00:00 2001
From: Lewis Liu <wei.zhi.liu@intel.com>
Date: Wed, 8 Apr 2020 16:57:40 +0800
Subject: [PATCH 2/2] update CMakefile for automatically selecting openCV4 or
 openCV3 judging from openCV installation situation.

---
 cv_bridge/CMakeLists.txt | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/cv_bridge/CMakeLists.txt b/cv_bridge/CMakeLists.txt
index 01d284668..642d32fdc 100644
--- a/cv_bridge/CMakeLists.txt
+++ b/cv_bridge/CMakeLists.txt
@@ -37,13 +37,23 @@ else()
 endif()
 
 find_package(sensor_msgs REQUIRED)
-find_package(OpenCV 4 REQUIRED
+
+find_package(OpenCV 4 QUIET
   COMPONENTS
     opencv_core
     opencv_imgproc
     opencv_imgcodecs
   CONFIG
 )
+if(NOT OpenCV_FOUND)
+  find_package(OpenCV 3 REQUIRED
+    COMPONENTS
+      opencv_core
+      opencv_imgproc
+      opencv_imgcodecs
+    CONFIG
+  )
+endif()
 
 if(NOT ANDROID)
   add_subdirectory(python)