How to draw curved and straight lines in one image?

I'm trying to draw a rectangle that is basically a circle, with a square on one end. Kind of like a battery. I have some limitations, basically this can only be done with a single paint object and should be able to support strokes.

Here is my code so far:

int width = 0;
int height = 0;

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    // myPath outline
    Point[] myPath = { new Point(20, 20), new Point(width, 20), new Point(width, height), new Point(20, height),
            new Point(20, height - 20), new Point(0, height - 20), new Point(0, height - 40),
            new Point(20, height - 40) };

    // Paint
    Paint paint = new Paint();
    int color = 0xffff0000;
    paint.setColor(color);
    paint.setAntiAlias(true);
    // paint.setPathEffect(new CornerPathEffect(15));
    paint.setStyle(Paint.Style.FILL);

    // Path moves
    Path path = new Path();

    path.moveTo(myPath[0].x, myPath[0].y);
    int j = myPath.length;
    for (int i = 0; i < j; i++) {
        path.lineTo(myPath[i].x, myPath[i].y);
    }
    path.close();

    Bitmap toDrawOn;
    toDrawOn = Bitmap.createBitmap(getWidth(), getHeight(), Config.ARGB_8888);
    Canvas ofScreen = new Canvas(toDrawOn);
    ofScreen.drawPath(path, paint);
    canvas.drawBitmap(toDrawOn, 0, 0, paint);

}

This gives me the desired shape of the cell, but I don't know how to round the first four corners without making the last four corners of the small square. Again, I need to make this shape a shape because I need to stroke it later. I also can't use 9patch because I need to change the color programmatically.

Here is my goal: