说明：  该类是本人花了两天制作完成的2D饼状图类。该类的功能第一是为了显示2D饼状图，第二是用于饼状图的鼠标设置，饼状图的各分块可以通过过鼠标实时自动设置，形象直观！
(I spent two days class is finished 2D pie chart class. The first such function is to display 2D pie chart, pie chart for the second mouse settings, pie chart of the sub-block can be automatically set by a mouse real-time, visually!)