Introduction - If you have any usage issues, please Google them yourself
Click the left mouse button, the program is to add a polygon vertex, vertex right-click you can add a finished filling! Currently individuals can fill concave polygons have been tested, if you download a friend to find out what is running where I am wrong please reply (hopefully be able to run down the right time to copy the entire screen, so easy to find my questions, thank you)! The program is written is not very smooth, but you can complete the scan-line fill function only!