Merge pull request #10050 from floe/android-studio-3.3.1

Add Android Mat constructor with support for native buffer (#10050)

modules/core/misc/java/test/MatTest.java

@@ -1,6 +1,7 @@
 package org.opencv.test.core;
 
 import java.util.Arrays;
+import java.nio.ByteBuffer;
 
 import org.opencv.core.Core;
 import org.opencv.core.CvException;
@@ -1001,4 +1002,16 @@ public class MatTest extends OpenCVTestCase {
         assertMatEqual(truth, dst);
     }
 
+    public void testMatFromByteBuffer() {
+        ByteBuffer bbuf = ByteBuffer.allocateDirect(64*64);
+        bbuf.putInt(0x01010101);
+        Mat m = new Mat(64,64,CvType.CV_8UC1,bbuf);
+        assertEquals(4, Core.countNonZero(m));
+        Core.add(m, new Scalar(1), m);
+        assertEquals(4096, Core.countNonZero(m));
+        m.release();
+        assertEquals(2, bbuf.get(0));
+        assertEquals(1, bbuf.get(4095));
+    }
+
 }