基于qwt第三方插件绘制正弦函数曲线，实现曲线的放大、缩小、移动。坐标动态变化等功能，运行前要安装qwt，代码是完整的，不要没有安装qwt就说代码不完整，就给差评的。看清楚说明了再下载-this is the sin curve base on the third plug-in components named qwt .before running make sure that it has installed the qwt