Rotate bmp image in C - c

Question

I'm rotating a bmp image file in C.
I successfully tested copying image(rotate 0 degree). But, It must be a problem in rotating image. Here is my code
#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#include<string.h>
#pragma warning (disable:4996)
#define FILENAMELENGTH 30
#define MAXROW 512
#define MAXCOL 512
//location of pixels
typedef struct
{
int row;
int col;
}COORDI;
//function declarations
void RotatePixel(float Theta, COORDI org, COORDI before, COORDI* after);
void ReadImage(char* original_image);
void WriteImage(char* rotate_image);
char source[MAXROW][MAXCOL];
char dest[MAXROW][MAXCOL];
COORDI org;
float Theta;
int main(void)
{
char original_image[FILENAMELENGTH];
char rotate_image[FILENAMELENGTH];
printf("image name : ");
scanf("%s", original_image);
//rotate angle(radian)
printf("angle : ");
scanf("%f", &Theta);
printf("after rotate file name : ");
scanf("%s", rotate_image);
org.row = MAXROW / 2;
org.col = MAXCOL / 2;
dest[MAXROW][MAXCOL] = { 0, };
ReadImage(original_image);
WriteImage(rotate_image);
printf("rotate completed!\n");
return 0;
}
void ReadImage(char* original_image)
{
FILE* fp;
int i, j;
fp = fopen(original_image, "rb");
if (fp == NULL)
{
printf("File cannot open\n");
exit(-1);
}
for (i = 0; i < MAXROW; i++)
{
for (j = 0; j < MAXCOL; j++)
fread(&source[i][j], sizeof(unsigned char), 1, fp);
}
printf("image read completed !\n");
fclose(fp);
return;
}
//writing a pixel to file
void WriteImage(char* rotate_image)
{
FILE* fp;
int i, j;
COORDI locn;
COORDI* after = (COORDI*)malloc(sizeof(COORDI));
fp = fopen(rotate_image, "wb");
if (fp == NULL)
{
printf("File cannot open\n");
exit(-1);
}
for (i = 0; i < MAXROW; i++)
{
for (j = 0; j < MAXCOL; j++)
{
locn.row = i;
locn.col = j;
RotatePixel(Theta, org, locn, after);
if (after->col < 0) continue;
if (after->row < 0) continue;
if (after->col >= MAXCOL) continue;
if (after->row >= MAXROW) continue;
dest[after->row][after->col] = source[i][j];
putc(dest[after->row][after->col], fp);
}
}
printf("image write completed !\n");
fclose(fp);
return;
}
//rotate pixels
void RotatePixel(float Theta, COORDI org, COORDI before, COORDI* after)
{
int x, y;
x = before.col - org.col;
y = before.row - org.row;
after->col = (int)(x* cos(Theta) - y*sin(Theta)) + org.col; // x
after->row = (int)(x* sin(Theta) + y*cos(Theta)) + org.row; // y
}
I think writing a pixel to file is a problem. where is the missing point?