/* dropdown.c
 *
 * by Revin Guillen
 *
 * Implements a drop-down list box
 *
 * Allegro GUI Clinic Example
 * http://students.washington.edu/revin/gui/
 */

#include <allegro.h>


int d_drop_down_proc(int msg, DIALOG *d, int c);


char *list_items[] = {
   "First",
   "Second",
   "Third",
   "Fourth",
   "Fifth",
   "Sixth",
   "Seventh",
   "Eighth",
   NULL
};

DIALOG main_dialog[] =
{
   /* (dialog proc)      (x)   (y)   (w)   (h)   (fg)  (bg)  (key) (flags)  (d1)  (d2)  (dp) */
   { d_clear_proc,       0,    0,    0,    0,    255,  0,    0,    0,       0,    0,    NULL },
   { d_drop_down_proc, 280,  110,   80,   20,    15,    0,    0,    0,       0,    0,    list_items },
   { NULL,               0,    0,    0,    0,    0,    0,    0,    0,       0,    0,    NULL }
};


/* d_drop_down_proc
 *
 *   A drop-down list box. The dp parameter should point
 *   to an array of strings to use for the list items. The
 *   array is terminated by a NULL entry. d1 holds the
 *   current selection. d2 is reserved.
 */
int d_drop_down_proc(int msg, DIALOG *d, int c)
{
  int num_items = 0;
  char **items = d->dp;
  int fgcol, bgcol;
  int old_x=-1, old_y=-1;
  int mx, my;
  int bot;
  int text_y, ry;
  int ht;
  int i;

  /* get the number of items */
  if (items != NULL) {
    while (items[num_items++] != NULL)
      ;
  }
  num_items--;

  /* clamp the value of the selection index */
  if (d->d1 >= num_items)
    d->d1 = num_items - 1;

  ht = text_height(font) + 4;

  bot = d->y + d->h + (ht*num_items);

  fgcol = (d->flags & D_DISABLED) ? gui_mg_color : d->fg;
  bgcol = d->bg;

  switch (msg)
  {
  case MSG_DRAW:

    if ( !(d->flags & D_HIDDEN) ) {

      rect(screen, d->x, d->y,
          d->x+d->w, d->y+d->h, fgcol);
      
      /* invert the colors */
      if (d->flags & D_GOTFOCUS) {
        i = fgcol;
        fgcol = bgcol;
        bgcol = i;
      }

      rectfill(screen, d->x+1, d->y+1, d->x+d->w-1, d->y+d->h-1, bgcol);

      text_mode(-1);
      text_y = d->y+(d->h/2)-(text_height(font)/2)+1;
      gui_textout(screen, items[d->d1], d->x+6, text_y, fgcol, 0);

      /* if we've got the focus */
      if (d->flags & D_GOTFOCUS) {
        for (i=d->x+2; i<d->x+d->w; i+=2) {
          putpixel(screen, i, d->y+2, fgcol);
          putpixel(screen, i, d->y+d->h-2, fgcol);
        }
        for (i=d->y+2; i<d->y+d->h; i+=2) {
          putpixel(screen, d->x+2, i, fgcol);
          putpixel(screen, d->x+d->w-2, i, fgcol);
        }
      }

      /* restore the colors */
      if (d->flags & D_GOTFOCUS) {
        i = fgcol;
        fgcol = bgcol;
        bgcol = i;
      }

      /* if we're dropped down */
      if (d->flags & D_SELECTED) {
        rect(screen, d->x, d->y+d->h, d->x+d->w, bot, fgcol);
        rectfill(screen, d->x+1, d->y+d->h+1, d->x+d->w-1, bot-1, bgcol);

        for (i=0; i<num_items; i++) {
          text_y = d->y+d->h+(i*ht)+3;

          if (i == d->d2) {
            ry = d->y+d->h+(i*ht);
            rectfill(screen, d->x+1, ry, d->x+d->w-1, ry+ht, fgcol);
            gui_textout(screen, items[i], d->x+4, text_y, bgcol, 0);
          } else {
            gui_textout(screen, items[i], d->x+4, text_y, fgcol, 0);
          }
        }
      }

    }
    break;

  case MSG_CLICK:

    if ( !(d->flags & D_HIDDEN) && !(d->flags & D_DISABLED) ) {

      d->d2 = -10000; /* below lowest possible */
      
      /* only works with the left mouse button */
      while (gui_mouse_b() & 0x01) {

        mx = gui_mouse_x();
        my = gui_mouse_y();

        if (((mx != old_x) || (my != old_y)) &&
           ((mx > d->x) && (mx < d->x+d->w) &&
            (my > d->y) && (my < bot ))) {

          old_x = mx;
          old_y = my;

          if (d->d2 != ((my-d->y-d->h)/ht)) {

            if (d->flags & D_SELECTED) {
              if (my >= d->y+d->h) {
                d->d2 = ((my-d->y-d->h)/ht);
              }
            } else {
              d->d2 = d->d1;
            }
            
            /* signals a dropped-down state */
            d->flags |= D_SELECTED;

            scare_mouse();

            /* redraw in the dropped-down position */
            SEND_MESSAGE(d, MSG_DRAW, 0);

            unscare_mouse();
          }

        }
      }

      /* return to non-dropped-down state */
      d->flags &= ~D_SELECTED;

      /* finalize the selection */
      if ((mx > d->x) && (mx < d->x+d->w) && (my > d->y) && (my < bot ))
        d->d1 = d->d2;

      return D_REDRAW;

    }
    break;

  case MSG_CHAR:

    if ( !(d->flags & D_HIDDEN) && !(d->flags & D_DISABLED)) {

      i=FALSE;

      if ((c >> 8) == KEY_UP) {
        if (d->d1 > 0)
          d->d1--;
        i=TRUE;
      } else if ((c >> 8) == KEY_DOWN) {
        if (d->d1 < num_items)
          d->d1++;
        i=TRUE;
      } else if ((c >> 8) == KEY_HOME) {
        d->d1 = 0;
        i=TRUE;
      } else if ((c >> 8) == KEY_END) {
        d->d1 = num_items;
        i=TRUE;
      }

      d->d2 = d->d1;
      scare_mouse();
      SEND_MESSAGE(d, MSG_DRAW, 0);
      unscare_mouse();

      if (i)
        return D_USED_CHAR;

    }
    break;

  case MSG_WANTFOCUS:

    return D_WANTFOCUS;
  }

  return D_O_K;
}


int main()
{
   /* initialize */
   allegro_init();
   install_keyboard(); 
   install_mouse();
   install_timer();
   set_gfx_mode(GFX_AUTODETECT, 640, 480, 0, 0);
   set_palette(desktop_palette);

   /* run the dialog */
   do_dialog(main_dialog, -1);

   return 0;
}