實現一個自定義波浪View

本文要實現的View如圖：

考慮到其還要放入其他控件，直接繼承RelativeLayout即可。
同時本文爲了簡單起見把自定義屬性去掉了，直接寫死各種屬性。
要實現這種效果，主要是計算需要畫多少個圓，通過觀察我們可以輕易算出：
（長度-間隔）/(2*半徑 + 間隔)
由於長度不一定剛好整除，所以我們需要考慮，首先獲取剩餘的長度：
（長度-間隔）%(2*半徑 + 間隔)
接下來需要考慮這個多餘的長度，將其平分加到間隔中去
看下源碼吧，道理弄清了很簡單：

public class SecondView extends RelativeLayout {
    private int gap = 8;
    private int radius = 10;
    private Paint mPaint;

    private float remain;
    private float remainY;
    private int circleNum;
    private int circleNumY;

    public SecondView(Context context) {
        super(context);
        init();
    }

    public SecondView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public SecondView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setDither(true);
        mPaint.setColor(Color.WHITE);
        mPaint.setStyle(Paint.Style.FILL);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        circleNum = (w - gap) / (2 * radius + gap);
        circleNumY = (h - gap) / (2 * radius + gap);

        remain = (w - gap) % (2 * radius + gap);
        remainY = (h - gap) % (2 * radius + gap);
    }

    @Override
    public void draw(Canvas canvas) {
        super.draw(canvas);
        for (int i = 0; i < circleNum; ++i) {
            canvas.drawCircle(gap + radius + remain / 2 + (gap + 2 * radius) * i, 0, radius, mPaint);
            canvas.drawCircle(gap + radius + remain / 2 + (gap + 2 * radius) * i, getMeasuredHeight(), radius, mPaint);
        }
        for (int i = 0; i < circleNumY; ++i) {
            canvas.drawCircle(0, gap + radius + remainY / 2 + (gap + 2 * radius) * i, radius, mPaint);
            canvas.drawCircle(getMeasuredWidth(), gap + radius + remainY / 2 + (gap + 2 * radius) * i, radius, mPaint);
        }
    }
}