#include "paint.h"

/* pos is a point on the unmagnified image */
static void
centercanvas(Widget *w, Point pos)
{
	Canvas *c;
	Point valid;

	c = w->aux;
	pos = mtoipt(pos, w);
	pos = subpt(pos, divpt(rectdim(w->r), 2));
	valid = subpt(mulpt(rectdim(c->s->mem->r), c->mag), rectdim(w->r));
	c->pos = clamppt(pos, Rpt(ZP, valid));
}

static int
mouse(Widget *w, Mousectl *mctl)
{
	Widget *root;
	Canvas *c;
	int but, mag;
	Point p, q, mc;
	Rectangle s, m;

	root = findrootwidget(w);
	c = w->aux;
	fastsetcursor(mctl, &sweepcursor);
	do {
		if((mctl->buttons & 7) == 0) {
			readmouse(mctl);
		} else {
			but = mctl->buttons;
			p = mctl->xy;
			do {
				q = mctl->xy;
				s = clamprect(canonrect(Rpt(p, q)), mtosrect(c->s->mem->r, w));
				w->redraw(w, RDall);
				antsrect(w->screen, w->r, s);
				readmouse(mctl);
			} while((mctl->buttons & 7) == but);

			if(mctl->buttons) {
				w->redraw(w, RDall);
				while(mctl->buttons)
					readmouse(mctl);
				continue;
			}

			m = stomrect(s, w);
			mc = divpt(addpt(m.min, m.max), 2);
			switch(but) {
			case 1:
				if(Dx(m) == 0 || Dy(m) == 0)
					c->mag = 1;
				else
					c->mag = max(c->mag * fmax((float)Dx(s)/Dx(w->r), (float)Dy(s)/Dy(w->r)), 1);
				centercanvas(w, mc);
				if(synccanvasimg(c, c->img->r) < 0) {
					fprint(2, "zoom: sync: %r\n");
					goto err;
				}
				root->resize(root, INFDIM);	/* w->resize might do a redundant sync */
				root->redraw(root, RDall);
				break;

			case 2:
				w->redraw(w, RDall);
				if((w = newzeroxwindow(w)) == nil) {
					fprint(2, "zerox: %r\n");
					goto err;
				}
				c = w->aux;
				root = findrootwidget(w);
				if(Dx(m) != 0 && Dy(m) != 0)
					c->mag = max(min((float)Dx(w->r)/Dx(m), (float)Dy(w->r)/Dy(m)), 1);
				centercanvas(w, mc);
				if(synccanvasimg(c, c->img->r) < 0) {
					fprint(2, "zerox: sync: %r\n");
					goto err;
				}
				root->redraw(root, RDall);
				goto done;

			case 4:
				if(Dx(m) == 0 || Dy(m) == 0)
					mag = c->mag + 1;
				else
					mag = max(min((float)Dx(w->r)/Dx(m), (float)Dy(w->r)/Dy(m)), 1);

				if(mag <= c->mag)
					mag = c->mag + 1;

				c->mag = mag;
				centercanvas(w, mc);
				if(synccanvasimg(c, c->img->r) < 0) {
					fprint(2, "zoom: sync: %r\n");
					goto err;
				}

				/* w->resize might do a redundant sync */
				root->resize(root, INFDIM);
				root->redraw(root, RDall);
				break;
			}
		}
	} while(ptinrect(mctl->xy, w->r));

done:
	fastsetcursor(mctl, nil);
	return 0;

err:
	fastsetcursor(mctl, nil);
	return -1;
}

CanvasTool zoom = {
	mouse,
};