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/src/java/core+Mat.java

@@ -1,5 +1,7 @@
 package org.opencv.core;
 
+import java.nio.ByteBuffer;
+
 // C++: class Mat
 //javadoc: Mat
 public class Mat {
@@ -39,6 +41,19 @@ public class Mat {
         return;
     }
 
+    //
+    // C++: Mat::Mat(int rows, int cols, int type, void* data)
+    //
+
+    // javadoc: Mat::Mat(rows, cols, type, data)
+    public Mat(int rows, int cols, int type, ByteBuffer data)
+    {
+
+        nativeObj = n_Mat(rows, cols, type, data);
+
+        return;
+    }
+
     //
     // C++: Mat::Mat(Size size, int type)
     //
@@ -1101,6 +1116,9 @@ public class Mat {
     // C++: Mat::Mat(int rows, int cols, int type)
     private static native long n_Mat(int rows, int cols, int type);
 
+    // C++: Mat::Mat(int rows, int cols, int type, void* data)
+    private static native long n_Mat(int rows, int cols, int type, ByteBuffer data);
+
     // C++: Mat::Mat(Size size, int type)
     private static native long n_Mat(double size_width, double size_height, int type);
 

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));
+    }
+
 }