# frame_box.ludic - what a host asks of the interface from outside it: the scale it is drawn at, and
# where an element was laid out the last time its screen was shown (a 3D view framed beside a panel)
export property UiBox {
  x: float = 0.0
  y: float = 0.0
  w: float = 0.0
  h: float = 0.0
}
# the screen pixels per design pixel: the renderer's scale (render3d's includes ui_render3d_scale)
export function ui_scale(ui_st: UiState) -> float { return ui_px(ui_st, 1.0) }
function fb_keep(ui_st: mut UiState, screen: string, root: UiNode) -> void {
  for i in 0 .. len(ui_st.fb_roots) {
    if ui_st.fb_roots[i].key == screen {
      ui_st.fb_roots[i] = root
      return
    }
  }
  ui_kept(ui_st.fb_roots, root)
}
# the box of the element with that id (or key) on any screen shown, in screen pixels; null if none
@alloc_ok("a question the game asks now and then (an anchor, a screen's box), never per frame")
export function ui_box(ui_st: UiState, id: string) -> UiBox {
  for i in 0 .. len(ui_st.fb_roots) {
    let n = fb_find(ui_st.fb_roots[i], id)
    if n != null {
      let b = new UiBox
      b.x = n.x
      b.y = n.y
      b.w = n.cw
      b.h = n.ch
      return b
    }
  }
  return null
}
function fb_find(n: UiNode, id: string) -> UiNode {
  if n.id == id or n.key == id { return n }
  if n.children == null { return null }
  for i in 0 .. len(n.children) {
    let f = fb_find(n.children[i], id)
    if f != null { return f }
  }
  return null
}