public void setWaveLength(int length) {
        length = Math.max(8, Math.min(mWidth * 2, length));
        if (length != mWaveLength) {
            mWaveLength = length;
            updateMask(mWidth, mWaveLength, mWaveHeight);
            invalidateSelf();
        }
    }
Set wave length (in pixels)
@param length
app/src/main/java/home/smart/fly/animations/customview/views/WaveDrawable.java