创建工具条，使用户能够通过工具条选择自己想要绘制的图形。使用鼠标绘图，通过添加鼠标消息处理函数对用户进行的鼠标操作进行监控并完成相应的图形绘制。(Create a toolbar that allows users to select the graphics they want to draw through the toolbar. Using mouse drawing, the user's mouse operation is monitored by adding a mouse m