Function l_selection_xor

src/nhlsel.c:331–356

local sel = selection.area(4,5, 40,10) ~ selection.rect(7,8, 60,14); */

/* local sel = selection.area(4,5, 40,10) ~ selection.rect(7,8, 60,14); */
staticfn int
l_selection_xor(lua_State *L)
{
    int x,y;
    struct selectionvar *sela = l_selection_check(L, 1);
    struct selectionvar *selb = l_selection_check(L, 2);
    struct selectionvar *selr = l_selection_push_new(L);
    NhRect rect = cg.zeroNhRect;

    rect_bounds(sela->bounds, selb->bounds, &rect);

    for (x = rect.lx; x <= rect.hx; x++)
        for (y = rect.ly; y <= rect.hy; y++) {
            int val = (selection_getpoint(x, y, sela)
                       ^ selection_getpoint(x, y, selb));

            selection_setpoint(x, y, selr, val);
        }
    /* this may have created a smaller or irregular selection with
     * bounds_dirty set to true - update its boundaries */
    selection_recalc_bounds(selr);

    lua_remove(L, 1);
    lua_remove(L, 1);
    return 1;
}

/* local sel = selection.area(10,10, 20,20) - selection.area(14,14, 17,17)
 *   - i.e. points that are in A but not in B */