# ui_scrollbar.ludic — a scroll box's bar held and dragged: a press on the thumb holds it where it
# was taken, the pointer held moves it in proportion, letting go leaves it; a press on the track
# jumps the thumb's middle there; the wheel still scrolls; and the rows under the bar are never pressed.
import "ludic.ui"
import "ui_scrollbar_parts/Long.ludic"
program UiScrollbar {
  numbers float
  var bx: float = 0.0
  var by: float = 0.0
  function frame(i: UiInput) -> UiNode {
    ui_input(i)
    ui_show("Long", null, 0.0, 0.0, 400.0, 400.0)
    let root: UiNode = ui_nodes("Long", null)
    ui_place(root, 0.0, 0.0, 400.0, 400.0)
    return root.children[0]
  }
  # the pointer at (bx + x, by + y), held or not; how far the box is scrolled then
  function at(x: float, y: float, down: bool) -> int {
    let i = new UiInput
    i.x = bx + x
    i.y = by + y
    i.down = down
    return int(frame(i).children[0].scroll_y)
  }
  function wheel(x: float, y: float) -> int {
    let i = new UiInput
    i.x = bx + x
    i.y = by + y
    i.wheel = 1.0
    frame(i)
    return int(frame(new UiInput).children[0].scroll_y)
  }
  entry {
    ui_backend(new UiBackend)
    let list = frame(new UiInput).children[0]
    bx = list.x
    by = list.y
    let grab = at(195.0, 10.0, true)
    let moved = at(195.0, 40.0, true)
    let far = at(195.0, 300.0, true)
    let back = at(195.0, 25.0, true)
    let kept = at(195.0, 25.0, false)
    at(0.0 - bx - 1.0, 0.0 - by - 1.0, false)
    let jump = at(195.0, 80.0, true)
    at(195.0, 80.0, false)
    let wheeled = wheel(50.0, 50.0)
    at(50.0, 20.0, true)
    at(50.0, 20.0, false)
    let page = frame(new UiInput)
    print(`grab {grab} moved {moved} far {far} back {back} kept {kept} | jump {jump} | wheel {wheeled} | {page.children[1].text}`)
  }
}