From 35bee663ebf28ee71d968d988811b3546f533e6d Mon Sep 17 00:00:00 2001
From: Hamdi Sahloul <hamdisahloul@hotmail.com>
Date: Thu, 20 Sep 2018 20:55:45 +0900
Subject: [PATCH 1/2] JS: Improves Emscripten detection

---
 modules/js/CMakeLists.txt | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/modules/js/CMakeLists.txt b/modules/js/CMakeLists.txt
index 6d713d4bd9..3d7caeb1c3 100644
--- a/modules/js/CMakeLists.txt
+++ b/modules/js/CMakeLists.txt
@@ -9,10 +9,29 @@ set(MODULE_NAME js)
 
 set(OPENCV_JS "opencv.js")
 
+find_path(EMSCRIPTEN_INCLUDE_DIR
+          emscripten/bind.h
+          PATHS
+            ENV EMSCRIPTEN_ROOT
+          PATH_SUFFIXES system/include include
+          DOC "Location of Emscripten SDK")
+
+if(NOT EMSCRIPTEN_INCLUDE_DIR OR NOT PYTHON_DEFAULT_AVAILABLE)
+  set(DISABLE_MSG "Module ${MODULE_NAME} disabled because the following dependencies are not found:")
+  if(NOT EMSCRIPTEN_INCLUDE_DIR)
+    message(STATUS "\${EMSCRIPTEN_INCLUDE_DIR}/emscripten/bind.h` was not detected")
+    set(DISABLE_MSG "${DISABLE_MSG} Emscripten")
+  endif()
+  if(NOT PYTHON_DEFAULT_AVAILABLE)
+    set(DISABLE_MSG "${DISABLE_MSG} Python")
+  endif()
+  message(STATUS ${DISABLE_MSG})
+  ocv_module_disable(${MODULE_NAME})
+endif()
+
 ocv_add_module(${MODULE_NAME} BINDINGS)
 
-# TODO: add emscripten path
-ocv_module_include_directories()
+ocv_module_include_directories(${EMSCRIPTEN_INCLUDE_DIR})
 
 # get list of modules to wrap
 # message(STATUS "Wrapped in ${MODULE_NAME}:")

From 95b1fe0776dd10b4e9f684ca2605c1898c0ca343 Mon Sep 17 00:00:00 2001
From: Hamdi Sahloul <hamdisahloul@hotmail.com>
Date: Thu, 20 Sep 2018 20:56:21 +0900
Subject: [PATCH 2/2] JS: Provides meaningful message in case of compile issues

---
 modules/js/src/make_umd.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/modules/js/src/make_umd.py b/modules/js/src/make_umd.py
index 4bca6c152b..7f7dffc880 100644
--- a/modules/js/src/make_umd.py
+++ b/modules/js/src/make_umd.py
@@ -103,4 +103,7 @@ if __name__ == "__main__":
     if len(sys.argv) > 2:
         opencvjs = sys.argv[1]
         cvjs = sys.argv[2]
+        if not os.path.isfile(opencvjs):
+            print('opencv.js file not found! Have you compiled the opencv_js module?')
+            exit()
         make_umd(opencvjs, cvjs);