Android设置重复文字水印背景

/**
 * Created by Owen Chan
 * On 2017-07-05.
 */

public class WaterMarkBg extends Drawable {

    private Paint paint = new Paint();

    private String logo = "SoYoung";

    public WaterMarkBg(String logo) {
        this.logo = logo;
    }

    @Override
    public void draw(@NonNull Canvas canvas) {


        int width = getBounds().right;
        int height = getBounds().bottom;

        canvas.drawColor(Color.parseColor("#F3F5F9"));
        paint.setColor(Color.parseColor("#AEAEAE"));
        paint.setAntiAlias(true);
        paint.setTextSize(30);
        canvas.save();
        canvas.rotate(-30);
        float textWidth = paint.measureText(logo);
        int index = 0;
        for (int positionY = height / 10; positionY <= height; positionY += height / 10) {
            float fromX = -width + (index++ % 2) * textWidth;
            for (float positionX = fromX; positionX < width; positionX += textWidth * 2) {
                canvas.drawText(logo, positionX, positionY, paint);
            }
        }
        canvas.restore();
    }

    @Override
    public void setAlpha(@IntRange(from = 0, to = 255) int alpha) {

    }

    @Override
    public void setColorFilter(@Nullable ColorFilter colorFilter) {

    }

    @Override
    public int getOpacity() {
        return PixelFormat.UNKNOWN;
    }
}

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.text).setBackground(new WaterMarkBg("Owen Chan"));
    }
}