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