Please add PencilSketch Effect

[EzequielAdrianM]

public class Sketch {
    //  type = 3(Negative), 4(Pencil Sketch), 5(Color Pencil Sketch)
    public static final Bitmap changeToSketch(Bitmap bitmap) {
        return changeToSketch(bitmap, 5,110);
    }

    public static final Bitmap changeToSketch(Bitmap src,int type,int threshold) {
        int width = src.getWidth();
        int height = src.getHeight();
        Bitmap result = Bitmap.createBitmap(width, height, src.getConfig());

        int A, R, G, B;
        int sumR, sumG, sumB;
        int[][] pixels = new int[3][3];
        for(int y = 0; y < height - 2; ++y) {
            for(int x = 0; x < width - 2; ++x) {
                //      get pixel matrix
                for(int i = 0; i < 3; ++i) {
                    for(int j = 0; j < 3; ++j) {
                        pixels[i][j] = src.getPixel(x + i, y + j);
                    }
                }
                // get alpha of center pixel
                A = Color.alpha(pixels[1][1]);
                // init color sum
                sumR = sumG = sumB = 0;
                sumR = (type*Color.red(pixels[1][1])) - Color.red(pixels[0][0]) - Color.red(pixels[0][2]) - Color.red(pixels[2][0]) - Color.red(pixels[2][2]);
                sumG = (type*Color.green(pixels[1][1])) - Color.green(pixels[0][0]) - Color.green(pixels[0][2]) - Color.green(pixels[2][0]) - Color.green(pixels[2][2]);
                sumB = (type*Color.blue(pixels[1][1])) - Color.blue(pixels[0][0]) - Color.blue(pixels[0][2]) - Color.blue(pixels[2][0]) - Color.blue(pixels[2][2]);
                // get final Red
                R = (int)(sumR  + threshold);
                if(R < 0) { R = 0; }
                else if(R > 255) { R = 255; }
                // get final Green
                G = (int)(sumG  + threshold);
                if(G < 0) { G = 0; }
                else if(G > 255) { G = 255; }
                // get final Blue
                B = (int)(sumB  + threshold);
                if(B < 0) { B = 0; }
                else if(B > 255) { B = 255; }

                result.setPixel(x + 1, y + 1, Color.argb(A, R, G, B));
            }
        }
        return result;
    }
}