6.1 演示案例【任务目标】 实现简单的绘图功能，并支持绘图数据的保存和打开等功能。通过 Draw 菜单，由用户点击选择不同的图形，按下鼠标左键并拖动鼠标开始绘图，松开鼠标后保存图形（线条、椭圆、矩形）数据，并更新屏幕显示。File 菜单下定义文件的基本操作， New 菜单项用于新建绘图文件，如果上一个文件修改了并没有保存，需要进行提示， Save 用于将绘图结果保存为磁盘文件，实现持久化存储， Open 用于打开存盘的图形文件。6.1.1 简单绘图版本
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001016s ]
SELECT `a`.`aid`,`a`.`title`,`a`.`create_time`,`m`.`username` FROM `jrk_downrecords` `a` INNER JOIN `jrk_member` `m` ON `a`.`uid`=`m`.`id` WHERE `a`.`status` = 1 GROUP BY `a`.`aid` ORDER BY `a`.`create_time` DESC LIMIT 10 [ RunTime:0.102534s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.000975s ]
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SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.000939s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003194s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000805s ]
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SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001017s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 231420 [ RunTime:0.028678s ]
