Merge pull request #7854 from alalek:backports_2016

(2.4) Backports from master branch (#7854)

modules/java/CMakeLists.txt

@@ -286,6 +286,9 @@ else(ANDROID)
 endif(ANDROID)
 
 # step 5: build native part
+ocv_warnings_disable(CMAKE_CXX_FLAGS -Wunused-const-variable -Woverloaded-virtual)
+
+
 add_library(${the_module} SHARED ${handwrittren_h_sources} ${handwrittren_cpp_sources} ${generated_cpp_sources}
                                  ${copied_files}
                                 "${JAR_FILE}" "${JAR_FILE}.dephelper")

modules/java/generator/src/java/android+JavaCameraView.java

@@ -328,6 +328,7 @@ public class JavaCameraView extends CameraBridgeViewBase implements PreviewCallb
         @Override
         public void run() {
             do {
+                boolean hasFrame = false;
                 synchronized (JavaCameraView.this) {
                     try {
                         while (!mCameraFrameReady && !mStopThread) {
@@ -337,11 +338,14 @@ public class JavaCameraView extends CameraBridgeViewBase implements PreviewCallb
                         e.printStackTrace();
                     }
                     if (mCameraFrameReady)
+                    {
                         mChainIdx = 1 - mChainIdx;
+                        mCameraFrameReady = false;
+                        hasFrame = true;
+                    }
                 }
 
-                if (!mStopThread && mCameraFrameReady) {
-                    mCameraFrameReady = false;
+                if (!mStopThread && hasFrame) {
                     if (!mFrameChain[1 - mChainIdx].empty())
                         deliverAndDrawFrame(mCameraFrame[1 - mChainIdx]);
                 }