Changed the way Images are converted into rgba Mats so that JavaCamera2View also…

Changed the way Images are converted into rgba Mats so that JavaCamera2View also shows correct colors when the Image contains I420 or YV12 data

modules/java/generator/android-21/java/org/opencv/android/JavaCamera2View.java

@@ -181,17 +181,7 @@ public class JavaCamera2View extends CameraBridgeViewBase {
                     assert (planes.length == 3);
                     assert (image.getFormat() == mPreviewFormat);
 
-                    // see also https://developer.android.com/reference/android/graphics/ImageFormat.html#YUV_420_888
-                    // Y plane (0) non-interleaved => stride == 1; U/V plane interleaved => stride == 2
-                    assert (planes[0].getPixelStride() == 1);
-                    assert (planes[1].getPixelStride() == 2);
-                    assert (planes[2].getPixelStride() == 2);
-
-                    ByteBuffer y_plane = planes[0].getBuffer();
-                    ByteBuffer uv_plane = planes[1].getBuffer();
-                    Mat y_mat = new Mat(h, w, CvType.CV_8UC1, y_plane);
-                    Mat uv_mat = new Mat(h / 2, w / 2, CvType.CV_8UC2, uv_plane);
-                    JavaCamera2Frame tempFrame = new JavaCamera2Frame(y_mat, uv_mat, w, h);
+                    JavaCamera2Frame tempFrame = new JavaCamera2Frame(image);
                     deliverAndDrawFrame(tempFrame);
                     tempFrame.release();
                     image.close();
@@ -334,50 +324,87 @@ public class JavaCamera2View extends CameraBridgeViewBase {
     private class JavaCamera2Frame implements CvCameraViewFrame {
         @Override
         public Mat gray() {
-            return mYuvFrameData.submat(0, mHeight, 0, mWidth);
+            Image.Plane[] planes = mImage.getPlanes();
+            int w = mImage.getWidth();
+            int h = mImage.getHeight();
+            ByteBuffer y_plane = planes[0].getBuffer();
+            mGray = new Mat(h, w, CvType.CV_8UC1, y_plane);
+            return mGray;
         }
 
         @Override
         public Mat rgba() {
-            if (mPreviewFormat == ImageFormat.NV21)
-                Imgproc.cvtColor(mYuvFrameData, mRgba, Imgproc.COLOR_YUV2RGBA_NV21, 4);
-            else if (mPreviewFormat == ImageFormat.YV12)
-                Imgproc.cvtColor(mYuvFrameData, mRgba, Imgproc.COLOR_YUV2RGB_I420, 4); // COLOR_YUV2RGBA_YV12 produces inverted colors
-            else if (mPreviewFormat == ImageFormat.YUV_420_888) {
-                assert (mUVFrameData != null);
-                Imgproc.cvtColorTwoPlane(mYuvFrameData, mUVFrameData, mRgba, Imgproc.COLOR_YUV2RGBA_NV21);
-            } else
-                throw new IllegalArgumentException("Preview Format can be NV21 or YV12");
+            Image.Plane[] planes = mImage.getPlanes();
+            int w = mImage.getWidth();
+            int h = mImage.getHeight();
+            int chromaPixelStride = planes[1].getPixelStride();
+
 
+            if (chromaPixelStride == 2) { // Chroma channels are interleaved
+                ByteBuffer y_plane = planes[0].getBuffer();
+                ByteBuffer uv_plane = planes[1].getBuffer();
+                Mat y_mat = new Mat(h, w, CvType.CV_8UC1, y_plane);
+                Mat uv_mat = new Mat(h / 2, w / 2, CvType.CV_8UC2, uv_plane);
+                Imgproc.cvtColorTwoPlane(y_mat, uv_mat, mRgba, Imgproc.COLOR_YUV2RGBA_NV21);
                 return mRgba;
+            } else { // Chroma channels are not interleaved
+                byte[] yuv_bytes = new byte[w*(h+h/2)];
+                ByteBuffer y_plane = planes[0].getBuffer();
+                ByteBuffer u_plane = planes[1].getBuffer();
+                ByteBuffer v_plane = planes[2].getBuffer();
+
+                y_plane.get(yuv_bytes, 0, w*h);
+
+                int chromaRowStride = planes[1].getRowStride();
+                int chromaRowPadding = chromaRowStride - w/2;
+
+                int offset = w*h;
+                if (chromaRowPadding == 0){
+                    // When the row stride of the chroma channels equals their width, we can copy
+                    // the entire channels in one go
+                    u_plane.get(yuv_bytes, offset, w*h/4);
+                    offset += w*h/4;
+                    v_plane.get(yuv_bytes, offset, w*h/4);
+                } else {
+                    // When not equal, we need to copy the channels row by row
+                    for (int i = 0; i < h/2; i++){
+                        u_plane.get(yuv_bytes, offset, w/2);
+                        offset += w/2;
+                        if (i < h/2-1){
+                            u_plane.position(u_plane.position() + chromaRowPadding);
+                        }
+                    }
+                    for (int i = 0; i < h/2; i++){
+                        v_plane.get(yuv_bytes, offset, w/2);
+                        offset += w/2;
+                        if (i < h/2-1){
+                            v_plane.position(v_plane.position() + chromaRowPadding);
+                        }
+                    }
                 }
 
-        public JavaCamera2Frame(Mat Yuv420sp, int width, int height) {
-            super();
-            mWidth = width;
-            mHeight = height;
-            mYuvFrameData = Yuv420sp;
-            mUVFrameData = null;
-            mRgba = new Mat();
+                Mat yuv_mat = new Mat(h+h/2, w, CvType.CV_8UC1);
+                yuv_mat.put(0, 0, yuv_bytes);
+                Imgproc.cvtColor(yuv_mat, mRgba, Imgproc.COLOR_YUV2RGBA_I420, 4);
+                return mRgba;
+            }
         }
 
-        public JavaCamera2Frame(Mat Y, Mat UV, int width, int height) {
+
+        public JavaCamera2Frame(Image image) {
             super();
-            mWidth = width;
-            mHeight = height;
-            mYuvFrameData = Y;
-            mUVFrameData = UV;
+            mImage = image;
             mRgba = new Mat();
+            mGray = new Mat();
         }
 
         public void release() {
             mRgba.release();
+            mGray.release();
         }
 
-        private Mat mYuvFrameData;
-        private Mat mUVFrameData;
+        private Image mImage;
         private Mat mRgba;
-        private int mWidth;
-        private int mHeight;
+        private Mat mGray;
     };
 }