利用C语言的Cairo图形库绘制太极图实例教程

#include <cairo.h>  #define SIZE (640) /* 太极图大小 */ #define CX (SIZE / 2) /* 太极圆中心横坐标 */ #define CY (SIZE / 2) /* 太极圆中心纵坐标 */ #define R (SIZE / 2) /* 太极圆半径 */  /* 把角度转换为所对应的弧度 */ #define ANGLE(ang) (ang * 3.1415926 / 180.0)  int main(int argc, char *argv[]) {  /* 创建32位RGBA颜色格式的Cairo绘图环境，直接在Memory中渲染 */  cairo_surface_t* surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, SIZE + 1, SIZE + 1);  cairo_t* cr = cairo_create(surface);   /* 绘制太极边框 */  cairo_set_line_width(cr, 2.0);  cairo_set_source_rgba(cr, 0, 0, 0, 1);  cairo_arc(cr, CX, CY, R, ANGLE(0), ANGLE(360));  cairo_stroke(cr);   /* 绘制阴阳圆 */  cairo_set_source_rgba(cr, 0, 0, 0, 1);  cairo_arc(cr, CX, CY, R, ANGLE(90), ANGLE(270));  cairo_fill(cr);  cairo_set_source_rgba(cr, 1, 1, 1, 1);  cairo_arc(cr, CX, CY, R, ANGLE(-90), ANGLE(90));  cairo_fill(cr);   /* 绘制阴阳线 */  cairo_set_source_rgba(cr, 0, 0, 0, 1);  cairo_arc(cr, CX, CY - R / 2, R / 2, ANGLE(-90), ANGLE(90));  cairo_fill(cr);  cairo_set_source_rgba(cr, 1, 1, 1, 1);  cairo_arc(cr, CX, CY + R / 2, R / 2, ANGLE(90), ANGLE(270));  cairo_fill(cr);   /* 绘制太极眼 */  cairo_set_source_rgba(cr, 1, 1, 1, 1);  cairo_arc(cr, CX, CY - R / 2, R / 10, ANGLE(0), ANGLE(360));  cairo_fill(cr);  cairo_set_source_rgba(cr, 0, 0, 0, 1);  cairo_arc(cr, CX, CY + R / 2, R / 10, ANGLE(0), ANGLE(360));  cairo_fill(cr);   /* 将Memory的渲染效果存储到图片中 */  cairo_surface_write_to_png(surface, "taichi.png");  /* 销毁并退出Cairo绘图环境 */  cairo_destroy(cr);  cairo_surface_destroy (surface);   return 0; } 

gcc -o taichi $(pkg-config --cflags --libs cairo) taichi.c