可以进行柱状图，饼状图和多边形的绘制， 并能对多边形进行扫描，使用扫描线算法-can histogram, pie slice and polygon rendering, polygon and is able to scan, use scan line algorithm

理解扫描转换多边形的扫描线算法原理 利用扫描线算法实现多边形的扫描转换 -Understand the scan line polygon scan conversion algorithm principle The scan line algorithm polygon scan conversion