【C语言练手】C语言画太极图

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

typedef struct {
                size_t width;
                size_t height;
                unsigned char *data;

} Image;

static Image * image_new (size_t width,
                                size_t height){
                Image *image;
                image = malloc (sizeof *image);
                image->width = width;
                image->height = height;
                image->data = malloc (width * height);
                return image;

}

static void

image_free (Image *image)

{
                free (image->data);
               free (image);
}
                static void

image_fill (Image *image,
                        unsigned char value)
{

                memset (image->data, value, image->width * image->height);

}



/**

 * image_set_pixel:

 *

 * Sets a pixel passed in signed (x, y) coordinates, where (0,0) is at

 * the center of the image.

 **/

static void

image_set_pixel (Image *image,

                                ssize_t x,

                                ssize_t y,

                                unsigned char value)

{

                size_t tx, ty;

                unsigned char *p;
                tx = (image->width / 2) + x;

                ty = (image->height / 2) + y;
                p = image->data + (ty * image->width) + tx;
 *p = value;

}



static void

image_save (const Image *image,

 const char *filename)

{

                FILE *out;
                out = fopen (filename, "wb");

 if (!out)

                                return;



                fprintf (out, "P5\n");

                fprintf (out, "%zu %zu\n", image->width, image->height);

                fprintf (out, "255\n");
                fwrite (image->data, 1, image->width * image->height, out);



                fclose (out);

}



static void draw_Taijitu(Image *image,int radius,int value)

{

 int x,y;

 int rlimit ,llimit;
 int radius_2 = radius*radius;

 for(y = -radius;y<radius;y++)

 for(x= -radius;x<radius;x++)
 if(x*x+y*y <= radius_2)

                          image_set_pixel(image,x,y,0xff);



 for(y = -radius;y<0;y++)

 for(x = 0;x<radius;x++)

 if((x*x)+(y*y) <= radius_2)

                          image_set_pixel(image,x,y,value);



 for(y = -radius;y<0;y++)

 for(x = -(int)sqrt((double)(-radius*y-y*y));x<0;x++)

                        image_set_pixel(image,x,y,value);

 for(y = 0;y<radius;y++)

 {

                                llimit = (int)sqrt((double)(radius*y - y*y));

                                rlimit = (int)sqrt((double)(radius_2 - y*y));

 for(x = llimit;x<rlimit;x++)

                                                image_set_pixel(image,x,y,value);

 }



 for(y = 2*radius/6;y<4*radius/6;y++)

 {

                                rlimit =(int) sqrt((double)(radius*y-y*y-2*radius_2/9));

                                llimit = -rlimit;
 for(x = llimit;x<rlimit;x++)

                                                image_set_pixel(image,x,y,value);

 }



 for(y = -4*radius/6;y<-2*radius/6;y++)

 {

                                rlimit = sqrt(-radius*y-y*y-2*radius_2/9);

                                llimit = -rlimit;

 for(x = llimit;x<rlimit;x++)

                                                image_set_pixel(image,x,y,0xff)
 }
                return ;
}

 int main (int argc, char *argv[])

{
                Image *image;
                image = image_new (800, 800);
                image_fill (image, 0xaa);

                draw_Taijitu (image, 300, 0);

                image_save (image, "taiji_6.pgm");
                image_free (image);
                return 0;

}