balancebox, add qml-box2d as git submodule and build target

Most distributions don't provide a packaged qml-box2d 2.0.
Therefore and to simplify things we build the qml-box2d automatically
as external target and install it under lib/qml/.

Therefore also GCompris now searches also in the relative path
../lib/qml for its qml plugins on desktop.

For android we add the module correspondingly.

The git submodule for now points directly to the upstream repo on
github.

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "external/qml-box2d"]
+	path = external/qml-box2d
+	url = https://github.com/qml-box2d/qml-box2d

CMakeLists.txt

@@ -260,3 +260,25 @@ if(SAILFISHOS)
   add_subdirectory(platforms/sailfishOS)
 endif()
 
+#
+# external: qml-box2d
+#
+
+include(ExternalProject)
+
+set (_box2d_install_dir ${CMAKE_CURRENT_BINARY_DIR}/lib/qml/Box2D.2.0)
+set (_box2d_source_dir ${CMAKE_CURRENT_SOURCE_DIR}/external/qml-box2d)
+
+ExternalProject_Add(qml_box2d
+                    DOWNLOAD_COMMAND ""
+                    SOURCE_DIR ${_box2d_source_dir}
+                    CONFIGURE_COMMAND qmake ${_box2d_source_dir}/box2d.pro
+                    BUILD_COMMAND make
+                    INSTALL_DIR ${_box2d_install_dir}
+                    INSTALL_COMMAND cp libBox2D.so ${_box2d_source_dir}/qmldir ${_box2d_install_dir}
+                   )
+
+add_library(qml-box2d SHARED IMPORTED)
+set_target_properties(qml-box2d PROPERTIES IMPORTED_LOCATION ${_box2d_install_dir}/libBox2D.so)
+
+install(DIRECTORY  ${_box2d_install_dir} DESTINATION lib/qml)

android/configAndroid.json.cmake

@@ -10,5 +10,6 @@
  "target-architecture": "@ARM_TARGET@",
  "application-binary": "@CMAKE_LIBRARY_OUTPUT_DIRECTORY@libGCompris.so",
  "android-package-source-directory": "@PACKAGE_SOURCE_ANDROID@/",
- "android-package": "net.gcompris"
+ "android-package": "net.gcompris",
+ "android-extra-plugins": "@CMAKE_BINARY_DIR@/lib/qml"
 }

src/core/main.cpp

@@ -228,6 +228,9 @@ int main(int argc, char *argv[])
     QQmlApplicationEngine engine(QUrl("qrc:/gcompris/src/core/main.qml"));
 	QObject::connect(&engine, SIGNAL(quit()), DownloadManager::getInstance(),
             SLOT(shutdown()));
+    // add import path for shipped qml modules:
+    engine.addImportPath(QStringLiteral("%1/../lib/qml")
+                         .arg(QCoreApplication::applicationDirPath()));
 
     if(parser.isSet(exportActivitiesAsSQL)) {
         ActivityInfoTree *menuTree(qobject_cast<ActivityInfoTree*>(ActivityInfoTree::menuTreeProvider(&engine, NULL)));