green screen

CameraActivity.java

 class MaskingGenerator extends AsyncTask<ActivityCameraBinding, Void, BitmapDrawable> {

        @Override
        protected BitmapDrawable doInBackground(ActivityCameraBinding... bindings) {
            try {
                ActivityCameraBinding b = bindings[0];
                int maxDispayW = b.camera.getWidth();
                int maxDispayH = b.camera.getHeight();

                if (maxDispayH <= 0 || maxDispayW <= 0) return null;
                // draw background
                Bitmap outerBg = Bitmap.createBitmap(maxDispayW, maxDispayH, Bitmap.Config.ARGB_8888);
                Canvas c = new Canvas(outerBg);


                Paint bg = new Paint();
                bg.setStyle(Paint.Style.FILL);
                bg.setColor(payloadData.outerBackgroundColor);
                c.drawPaint(bg);

                // draw masking hole, crop
                Drawable maskDrawable = b.overlay.getDrawable();
                Bitmap mask = convertToBitmap(maskDrawable,
                        b.overlay.getWidth(), b.overlay.getHeight());
                float maskX = b.overlay.getX();
                float maskY = b.overlay.getY();

                Paint rectPaint = new Paint();
                rectPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
                rectPaint.setStyle(Paint.Style.FILL);
                rectPaint.setAntiAlias(true);
                c.drawBitmap(mask, maskX, maskY, rectPaint);
                mask.recycle();

                // draw original color, exclude Green color
                // The matrix is stored in a single array, and its treated as follows: [ a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t ]
                // When applied to a color [r, g, b, a], the resulting color is computed as (after clamping) ;
                //   R' = a*R + b*G + c*B + d*A + e;
                //   G' = f*R + g*G + h*B + i*A + j;
                //   B' = k*R + l*G + m*B + n*A + o;
                //   A' = p*R + q*G + r*B + s*A + t;
                float[] matrix = {
                        1, 0, 0, 0, 0, //red
                        0, 1, 0, 0, 0, //green
                        0, 0, 1, 0, 0, //blue
                        0, -1, 0, 1, 0, //alpha
                };

                ColorMatrixColorFilter removeGreenFilter = new ColorMatrixColorFilter(matrix);
                Drawable maskDEx = maskDrawable.getConstantState().newDrawable();
                maskDEx.setColorFilter(removeGreenFilter);
                Bitmap maskEx = convertToBitmap(maskDEx,
                        b.overlay.getWidth(), b.overlay.getHeight());
                rectPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OVER));
                c.drawBitmap(maskEx, maskX, maskY, rectPaint);
                maskEx.recycle();


                // assign to view
                BitmapDrawable res = new BitmapDrawable(getResources(), outerBg);
                res.setAntiAlias(true);
                return res;

            } catch (Exception e) {
            }

            return null;
        }

        @Override
        protected void onPostExecute(BitmapDrawable res) {
            binding.overlayOuter.setImageDrawable(res);
            binding.overlayOuter.setVisibility(View.VISIBLE);
            binding.overlay.setVisibility(View.INVISIBLE);
        }
    };