/* Edouard.Thiel@lif.univ-mrs.fr */
#include <helium.h>


#define NBP 4
#define SUBDIV 2

int pt_x[NBP] = { 10, 60, 20, 35 },
    pt_y[NBP] = { 90, 80, 40, 70 };

He_node *princ, *canvas;
int canvas_w, canvas_h, coul1, coul2, coul3;


void dessin_curseur (Window win, int x, int y)
{
    int l = 4;
    XDrawRectangle (he_display, win, he_gc, x-l, y-l, l*2, l*2);
}


void dessin_ligne (Window win, int i, int j, int a, int b, int c, int d)
{
    double r = (double) i / (double) SUBDIV;
    double s = (double) j / (double) SUBDIV;
    double lx = (pt_x[b] - pt_x[a]) * r + (pt_x[d] - pt_x[a]) * s;
    double ly = (pt_y[b] - pt_y[a]) * r + (pt_y[d] - pt_y[a]) * s;

    XDrawLine (he_display, win, he_gc,
    	    pt_x[a]+lx, pt_y[a]+ly, pt_x[c]+lx, pt_y[c]+ly);
}


void canvas_repaint (He_node *canvas, Window win)
{
    int i, j;

    XSetForeground (he_display, he_gc, he_white);
    XFillRectangle (he_display, win, he_gc, 
	0, 0, canvas_w, canvas_h );

    XSetForeground (he_display, he_gc, he_black);
    for (i = 0; i < NBP; i++) 
	dessin_curseur (win, pt_x[i], pt_y[i]);

    XSetForeground (he_display, he_gc, coul1);
    for (i = 0; i <= SUBDIV; i++) 
    for (j = 0; j <= SUBDIV; j++)
	dessin_ligne (win, i, j, 0, 1, 2, 3);

    XSetForeground (he_display, he_gc, coul2);
    for (i = 0; i <= SUBDIV; i++) 
    for (j = 0; j <= SUBDIV; j++)
	dessin_ligne (win, i, j, 0, 2, 3, 1);

    XSetForeground (he_display, he_gc, coul3);
    for (i = 0; i <= SUBDIV; i++) 
    for (j = 0; j <= SUBDIV; j++)
	dessin_ligne (win, i, j, 0, 3, 1, 2);
}


int cherche_clic (int xo, int yo)
{
    int i, d = 5;

    for (i = 0; i < NBP; i++)
	if ( abs(pt_x[i] - xo) < d && abs(pt_y[i] - yo) < d)
	    return i;

    return -1;
}


void canvas_event (He_node *canvas, He_event *hev)
{
    static int n = -1;
    
    switch (hev->type) {

	case ButtonPress : 
	    n = cherche_clic (hev->sx, hev->sy);
	    break;

	case MotionNotify :
	    if (n >= 0) {
		pt_x[n] = hev->sx; pt_y[n] = hev->sy;
		HePostRepaint (canvas);
	    }
	    break;

	case ButtonRelease :
	    if (n >= 0) {
                if (pt_x[n] < 0) pt_x[n] = 0;
                else if (pt_x[n] >= canvas_w) pt_x[n] = canvas_w-1;
                if (pt_y[n] < 0) pt_y[n] = 0;
                else if (pt_y[n] >= canvas_h) pt_y[n] = canvas_h-1;
                n = -1;
		HePostRepaint (canvas);
            }
	    break;
    }
}


void princ_resize (He_node *princ, int width, int height)
{
    HeExpand (canvas, NULL, HE_BOTTOM_RIGHT);
}


void canvas_resize (He_node *canvas, int width, int height)
{
    int i;

    for (i = 0; i < NBP; i++) {
	pt_x[i] = (pt_x[i] * width ) / canvas_w;
	pt_y[i] = (pt_y[i] * height) / canvas_h;
    }

    canvas_w = width;
    canvas_h = height;
}


int main (int argc, char *argv[])
{
    int i;

    HeInit (&argc, &argv);

    princ = HeCreateFrame ();
    HeSetFrameLabel (princ, "Grille cubique");
    HeSetFrameResizeProc (princ, princ_resize);

    canvas = HeCreateCanvas (princ);
    HeSetCanvasDBuf (canvas, TRUE);
    HeSetCanvasResizeProc (canvas, canvas_resize);
    HeSetCanvasRepaintProc (canvas, canvas_repaint);
    HeSetCanvasEventProc (canvas, canvas_event);
    HeSetTip (canvas, "Bouton 1 : déplacer les points de contrôle");

    coul1 = HeAllocRgb (   0, 255,   0, he_black);
    coul2 = HeAllocRgb ( 255,   0,   0, he_black);
    coul3 = HeAllocRgb (   0,   0, 255, he_black);

    /* Init points */
    canvas_w = HeGetWidth (canvas);
    canvas_h = HeGetHeight(canvas);

    for (i = 0; i < NBP; i++) {
	pt_x[i] *= canvas_w; pt_x[i] /= 100;
	pt_y[i] *= canvas_h; pt_y[i] /= 100;
    }

    return HeMainLoop (princ);
}