# backend.ludic - the renderer seam: what a renderer draws, and nothing more. Only rect, text and
# measure are needed; the rest improve on a default (a rounded rect falls back to a square one, an
# image to nothing). Input is the runtime's own (Input.*), so no renderer has to supply it.
export property UiBackend {
  rect: fn(float, float, float, float, int, float) -> void = null                 # x y w h rgb alpha
  round: fn(float, float, float, float, float, int, float) -> void = null         # ... radius rgb alpha
  ring: fn(float, float, float, float, float, float, int, float) -> void = null  # x y w h radius width rgb alpha
  text: fn(float, float, string, float, int, float) -> void = null                # x y text size rgb alpha
  measure: fn(string, float) -> float = null
  image: fn(string, float, float, float, float, int, float) -> void = null        # src x y w h tint alpha
  image_w: fn(string) -> float = null     # a picture's own size, for object-fit
  image_h: fn(string) -> float = null
  nine: fn(string, float, float, float, float, float, float, int, float) -> void = null  # src slice x y w h width tint alpha (ui_nine_cuts)
  clip: fn(float, float, float, float) -> void = null
  unclip: fn() -> void = null
  scale: fn() -> float = null      # screen pixels per design pixel
  pointer_scale: fn() -> float = null   # screen pixels per unit of Input.mouse_x/y (2 on Retina)
  translate: fn(string) -> string = null   # the program's language, for every text a template shows
  sound: fn(string) -> void = null         # a control was used: "click", or its sound="..."
  read: fn(string) -> string = null        # a template file's text (else Fs.read_text)
  now: fn() -> float = null                # seconds, for animation (else frames at 60 a second)
  input: bool = true               # false: take no input from Input.* (a test drives it)
  said: fn(string) -> void = null          # a template error, for a host that reports it itself (else printed)
  emitted: fn(string) -> void = null       # `emit name` ran, whether or not a handler took it (a host's log)
}
# a renderer a program installs by importing it (render3d.ludic): the first one is the backend
property UiRenderer {
  key: string = ""
  make: fn() -> UiBackend = null
}
registry UiRenderers of UiRenderer as UIR
function ui_default_backend() -> UiBackend {
  if len(UiRenderers) == 0 { return null }
  return UiRenderers[0].make()
}
export state UiState {
  @max(512) pl_pools: []UiPool = new []UiPool      # pool.ludic: each screen's nodes and envs, used again
  pl_cur: UiPool = null
  uv_on: bool = false                    # pool.ludic: a build is under way, so expressions' Values are pooled
  uv_true: Val = null
  uv_false: Val = null
  mm: UiMemo = null                      # memo.ludic: splits, gradients and keys by their text
  mm_ints: []string = null
  mm_negs: []string = new []string        # memo_join.ludic: negative numbers' texts, and the last big ones
  mm_big_v: []int = new []int
  mm_big_s: []string = new []string
  mm_big_at: int = 0
  fc_none: Val = Value.null()            # focus.ludic: the value a key's down and up carry, made once
  mm_ivals: []Val = null
  ev_depth: int = 0                      # eval.ludic: a call's arguments, in lists kept one a depth
  ev_args: []Val = new []Val
  @max(64) ev_ring: []Val = ev_ring_new()         # eval.ludic: calls' answers while an action runs, EV_RING of them, made with the state
  ev_ring_at: int = 0
  nt_evs: []Val = nt_evs_new()          # native.ludic: fired events' objects, NT_EVS of them, made with the state
  nt_ev_at: int = 0
  nt_nums: []Val = nt_nums_new()        # fired.ludic: the numbers a scroll or a slider reports, a ring
  nt_num_at: int = 0
  ct_clamp_n: []UiNode = new []UiNode   # controls_opts.ludic: selects whose value a build clamped
  ct_clamp_i: []int = new []int
  hd_ev: Val = hd_ev_new()               # hold.ludic: the held control's event, filled in place
  cv_texts: []string = new []string      # units_pieces.ludic: a value's var() pieces, kept
  tx_pieces: [][]string = new [][]string # eval_text.ludic: a text's pieces, a list a depth
  tx_depth: int = 0
  ca_pool: []CaVal = new []CaVal         # calc.ludic: an evaluation's terms, used again by the next
  ca_used: int = 0
  ca_args: [][]CaVal = new [][]CaVal
  ca_depth: int = 0
  @max(16) pe_evs: []UiPointer = pe_evs__new()   # pointer_events.ludic: an event's record and its Value, a ring
  @max(16) pe_vals: []Val = pe_vals__new()
  pe_at: int = 0
  nth_a: int = 0                         # select_nth.ludic: the a and b just read
  nth_b: int = 0
  tt_src: string = null                  # tooltip.ludic: the title tt_text was translated from
  fit_out: []float = new []float         # draw_content.ludic: an image's box, kept
  r3n_cut: []float = new []float         # render3d_nine.ludic: a nine-slice's edges, kept
  r3n_xs: []float = new []float
  r3n_ys: []float = new []float
  r3n_us: []float = new []float
  r3n_vs: []float = new []float
  ly_depth: int = 0                      # layout_run.ludic: the lists a line lays out with, one a depth
  ly_sizes: [][]float = new [][]float
  ly_frozen: [][]bool = new [][]bool
  cs_rules: []UiRule = new []UiRule      # cascade_merge.ludic: a component root's rules, gathered
  cs_envs: []UiEnv = new []UiEnv
  cs_seen: []UiSheet = new []UiSheet
  an_frames: []UiKeyframes = new []UiKeyframes
  an_keys: []string = new []string
  an_start: []float = new []float
  an_frame: int = 0
  el_s0: float = 0.0
  el_s1: float = 0.0
  el_s2: float = 0.0
  el_s3: float = 0.0
  ui_be: UiBackend = ui_default_backend()
  tr_no: bool = false        # inside translate="no" while a frame is built
  ca_s: string = ""
  ca_i: int = 0
  ca_bad: string = ""
  ca_px: float = 0.0            # the result: its lengths, its percentage, and whether it had units
  ca_pct: float = 0.0
  ca_num: float = 0.0           # a plain number's own value, and whether it was one
  ca_bare: bool = false
  cs_pass: int = 0
  ua_sh: UiSheet = null
  uc_list: []UiClass = new []UiClass     # filled by the compiler's registrations, before the program's globals
  cl_alpha: float = 1.0
  ct_capture: string = ""
  ct_capture_at: int = -1       # the frame listening began, whose own key started it
  ct_capture_seen: int = -1     # the last frame that began listening, for ui_capturing
  ct_num_key: string = ""
  ct_num_text: string = ""
  dv_on: bool = false
  dv_frames: int = 0
  dv_dumped: bool = false
  fr_ga: float = 1.0           # the opacity of everything around this element, which it multiplies
  gr_a: float = 1.0
  fr_clips: []float = new []float
  ui_view: UiView = null
  ui_errs: []string = new []string
  ui_at: string = ""
  fc_key: string = ""
  fc_visible: bool = false    # focus came from the keyboard: :focus-visible, and the ring
  fc_list: []UiNode = new []UiNode
  fb_roots: []UiNode = new []UiNode
  hd_key: string = ""
  hd_t0: float = 0.0
  hd_last: float = 0.0
  in_now: UiInput = new UiInput
  in_was_down: bool = false
  in_last: UiInput = new UiInput
  in_rec_a: UiInput = new UiInput
  in_rec_b: UiInput = new UiInput
  in_given: bool = false
  rp_next: []float = [-1.0, -1.0, -1.0, -1.0]
  rp_a: bool = false
  rp_b: bool = false
  rp_act: bool = false
  in_act_down: bool = false   # A or Enter went down this frame, or came up
  in_act_up: bool = false
  in_list: []UiInst = new []UiInst
  in_free: []UiInst = new []UiInst     # unmounted instances, each mounted again as its class's next one
  in_build: int = 0
  ly_fg_a: float = 1.0
  ly_lead: float = 0.0
  ly_extra: float = 0.0
  lib_files: []UiFile = new []UiFile
  lib_screen_names: []string = new []string
  lib_screens: []UiTpl = new []UiTpl
  lc_keys: []string = new []string
  lc_mounts: []UiAct = new []UiAct
  lc_unmounts: []UiAct = new []UiAct
  lc_envs: []UiEnv = new []UiEnv
  lc_sp_keys: []string = new []string    # life.ludic: the spare set lc_run fills and swaps in
  lc_sp_unmounts: []UiAct = new []UiAct
  lc_sp_envs: []UiEnv = new []UiEnv
  lc_prev_keys: []string = new []string
  lc_prev_unmounts: []UiAct = new []UiAct
  lc_prev_envs: []UiEnv = new []UiEnv
  nt_list: []UiNative = new []UiNative
  nt_sp_nodes: []UiNode = nt_nodes__new()   # native.ludic: the queue's spare, swapped while it runs;
  nt_sp_names: []string = nt_names__new()   # each list is made with room for a busy frame's events
  nt_sp_vals: []Val = nt_vals__new()
  nt_q_nodes: []UiNode = nt_nodes__new()
  nt_q_names: []string = nt_names__new()
  nt_q_vals: []Val = nt_vals__new()
  fr_hover: []string = new []string
  fr_hover_sp: []string = new []string
  fr_press_key: string = ""
  fr_down_now: bool = false
  fr_key_press: string = ""   # the control Enter or the pad's A is holding down
  pe_key: string = ""         # the element the pointer is captured by
  pe_btn: int = 0
  pop_list: []UiNode = new []UiNode
  pop_spare: []UiNode = new []UiNode
  pp_bx: float = 0.0
  pp_by: float = 0.0
  pp_bw: float = 0.0
  pp_bh: float = 0.0
  r3u_user: float = 1.0
  r3u_tex_paths: []string = new []string
  r3u_tex_ids: []int = new []int
  r3u_tex_sizes: []int = new []int
  r3u_tex_seen: []float = new []float
  r3u_atlas: []string = new []string
  r3u_atlas_tex: []int = new []int
  r3u_atlas_cols: []int = new []int
  r3u_atlas_rows: []int = new []int
  r3u_atlas_names: [][]string = new [][]string
  sc_keys: []string = new []string
  sc_offs: []float = new []float
  sc_drag: string = ""
  sc_scope: UiNode = null      # the popover that has the pointer this frame, if one is up
  sb_x: float = 0.0
  sb_w: float = 0.0
  sb_ty: float = 0.0
  sb_th: float = 0.0
  sb_bar: UiNode = null
  sc_grab: float = 0.0        # how far below the thumb's top the pointer holds it
  sc_want_keys: []string = new []string
  sc_want_px: []float = new []float
  st_keys: []string = new []string
  st_vals: []Val = new []Val
  tf_size: float = 0.0        # the size tf_fit drew at
  tt_key: string = ""
  tt_since: float = 0.0
  tt_text: string = ""
  tt_x: float = 0.0
  tt_y: float = 0.0
  tt_by_keys: bool = false    # the focus moved by the keyboard since the pointer last moved
  tt_focus_seen: string = ""
  tp_nl: []int = new []int
  tr_keys: []string = new []string
  tr_from: []float = new []float
  tr_to: []float = new []float
  tr_at: []float = new []float
  el_cur: UiNode = null
  el_key: string = ""
  ly_vp_x: float = 0.0
  ly_vp_y: float = 0.0
  ly_vp_w: float = 0.0
  ly_vp_h: float = 0.0
}
export function ui_backend(ui_st: mut UiState, b: UiBackend) -> void { ui_st.ui_be = b }
function ui_px(ui_st: UiState, v: float) -> float {
  if ui_st.ui_be != null and ui_st.ui_be.scale != null { return v * ui_st.ui_be.scale() }
  return v
}
function ui_tr(ui_st: UiState, s: string) -> string {
  if ui_st.tr_no { return s }
  if ui_st.ui_be != null and ui_st.ui_be.translate != null { return ui_st.ui_be.translate(s) }
  return s
}
function ui_sound(ui_st: UiState, name: string) -> void {
  if ui_st.ui_be != null and ui_st.ui_be.sound != null { ui_st.ui_be.sound(name) }
}
# the program's language: every text a template shows goes through `f` before it is measured
export function ui_translator(ui_st: mut UiState, f: fn(string) -> string) -> void {
  if ui_st.ui_be != null { ui_st.ui_be.translate = f }
}
# the program's sounds: "click" when a control is used, or the control's own sound="..."
export function ui_sounds(ui_st: mut UiState, f: fn(string) -> void) -> void {
  if ui_st.ui_be != null { ui_st.ui_be.sound = f }
}
# the program's clock, in seconds, for animation (a game's own time, which a headless run counts)
export function ui_clock(ui_st: mut UiState, f: fn() -> float) -> void {
  if ui_st.ui_be != null { ui_st.ui_be.now = f }
}