QT下一个使用Qcanvas绘制点，线，多边形的绘图程序

FTGL源代码，FTGL为Qt下多种形式文字输入的插件库，支持多边形和位图等文字的输入。-FTGL source code, FTGL under the various forms of text input for the Qt library plug-ins, support polygons and bitmaps and other text input.

一个简单的画图工具，可以画各种常见的图形如矩形、圆形、椭圆、多边形等。还可以改变画笔颜色、大小。-A simple drawing tools, you can draw a variety of common graphics such as rectangles, circles, ellipses, polygons, and so on. You can also change the pen color, size.