// PROGRAM circle

#include "TrueBASIC.h"
int main();
void compute_aspect_ratio(float r, float *x, float *y);

int main()
{
    float r, xwin, ywin;

    GWopen(0);

    r = 1;                                  // radius of circle
    compute_aspect_ratio(r, &xwin, &ywin);
    GWindow(-xwin, -ywin, xwin, ywin);
    GWsetpen(BLUE, -1, -1, -1);
    GWellipse(-r, -r, r, r);                // draw circle

    GWquit();
    return 0;
}

void compute_aspect_ratio(float r, float *x, float *y)
{
    int px, py;
    float aspect_ratio, m, size;

    m = 0.1f*r;                              // margin
    size = r + m;
    // px, py: # pixels in horizonal and vertical direction
    GWsize(2, &px, &py);
    if(px > py)
    {
        aspect_ratio = (float)px/py;
        (*x) = aspect_ratio*size;
        (*y) = size;
    }
    else
    {
        aspect_ratio = (float)py/px;
        (*x) = size;
        (*y) = aspect_ratio*size;
    }
}