DrawCircles.java

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    int width = getWidth();
    int height = getHeight();

    // o ㅡㅡ o
    //
    //
    // o     o
    resetPaint(0);
    float[] circleCenter = getHorizontalCenter(width, height, true);
    canvas.drawCircle(circleCenter[0], circleCenter[1], radius, paint);


    // o      o
    //        |
    //        |
    // o      o
    resetPaint(1);
    circleCenter = getVerticalCenter(width, height, true);
    canvas.drawCircle(circleCenter[0], circleCenter[1], radius, paint);


    // o     o
    //
    //
    // o ㅡㅡ o
    resetPaint(2);
    circleCenter = getHorizontalCenter(width, height, false);
    canvas.drawCircle(circleCenter[0], circleCenter[1], radius, paint);


    // o      o
    // ㅣ
    // ㅣ
    // o      o
    resetPaint(3);
    circleCenter = getVerticalCenter(width, height, false);
    canvas.drawCircle(circleCenter[0], circleCenter[1], radius, paint);
}