Vietnam flag

FlagPainter.java

public class FlagPainter {

    private static final int PENTAGON = 5;
    private static final float ROTATE = -18F;

    private Bitmap drawStar(int size) {
        Path path;
        Paint paint = new Paint();
        Matrix matrix = new Matrix();
        paint.setColor(Color.YELLOW);
        paint.setAntiAlias(true);

        Bitmap bitmap;
        bitmap = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);

        Canvas canvas = new Canvas(bitmap);

        float halfWidth = bitmap.getWidth() / 2.0F;
        path = createStarBySyze(bitmap.getWidth(), PENTAGON);
        matrix.postRotate(ROTATE, halfWidth * 1.3F, halfWidth * 1.05F);
        path.transform(matrix);

        canvas.drawPath(path, paint);

        return bitmap;
    }

    public Bitmap drawFlag(int size) {

        Bitmap bitmap;
        bitmap = Bitmap.createBitmap(size, size, Bitmap.Config.RGB_565);

        int halfSize = size / 2;
        Bitmap star = drawStar(halfSize);
        Canvas canvas = new Canvas(bitmap);

        int midPos = halfSize / 2;
        canvas.drawColor(Color.RED);
        canvas.drawBitmap(star, midPos, midPos, null);
        return bitmap;
    }

    private Path createStarBySyze(float width, int steps) {
        float halfWidth = width / 2.0F;
        float bigRadius = halfWidth;
        float radius = halfWidth / 2.5F;
        float degreesPerStep = (float) Math.toRadians(360.0F / (float) steps);
        float halfDegreesPerStep = degreesPerStep / 2.0F;
        Path ret = new Path();
        ret.setFillType(Path.FillType.EVEN_ODD);
        float max = (float) (2.0F * Math.PI);
        ret.moveTo(width, halfWidth);
        for (double step = 0; step < max; step += degreesPerStep) {
            ret.lineTo((float) (halfWidth + bigRadius * Math.cos(step)), (float) (halfWidth + bigRadius * Math.sin(step)));
            ret.lineTo((float) (halfWidth + radius * Math.cos(step + halfDegreesPerStep)), (float) (halfWidth + radius * Math.sin(step + halfDegreesPerStep)));
        }
        ret.close();
        return ret;
    }
}