Cairo is a 2D graphics library with support for multiple output devices. Currently supported output targets include the X Window System, Quartz, Win32, image buffers, Postscr ipt, PDF, and SVG file output. Experimental backends include OpenGL (throug

采用c语言，openGL，按1,2,3,4键可以显示四种图形，1-圆形，2-三角形，3-盘圆，4-直线，按r可缩小图形，R放大图形-Using c language, openGL Press 1,2,3,4 keys can display four graphics- Round 2- triangle, 3- coiled, 4- a straight line and can narrow the graphics r, R amplification graphics