Chrysalisp Gui Apps

ChrysaLisp GUI App Skill

A ChrysaLisp GUI app is a long-running task that owns a window, renders a widget tree, and dispatches events from a mailbox select loop. The general ChrysaLisp disciplines (see the chrysalisp skill, LLM.md, and docs/ai_digest/) apply on top of these app-specific patterns.

Canonical File Structure

Copy apps/template/ as the starting point for a new app:

• app.lisp: Entry point — imports, mailbox setup, the main event loop.

• widgets.inc: Declarative UI definition — the widget tree, event enums, and tool tips.

• actions.inc: The switchboard — maps event IDs to action functions and key codes to actions.

• ui.inc: The action handler implementations (application logic).

• utils.inc, clipboard.inc, undo.inc: Helper, clipboard, and undo/redo logic.

Reference apps: apps/desktop/docs/ (good but simple), apps/tools/edit/ (complex, with services and RPC), and apps/demos/boing/ (timer-driven animation).

app.lisp — The Event Loop

;debug options
(case 2
(0 (import "lib/debug/frames.inc"))
(1 (import "lib/debug/profile.inc"))
(2 (import "lib/debug/debug.inc")))

(import "usr/env.inc")
(import "gui/lisp.inc")
(import "service/clipboard/app.inc")

;our UI widgets
(import "./widgets.inc")

(enums +select 0
	(enum main tip timer))

(defq +rate (/ 1000000 1))

;import actions and bindings
(import "./actions.inc")

(defun dispatch-action (&rest action)
	(catch (eval action) (progn (prin _) (print) :t)))

(defun main ()
	(defq select (task-mboxes +select_size) *running* :t)
	(def *window* :tip_mbox (elem-get select +select_tip))
	(bind '(x y w h) (apply view-locate (. *window* :pref_size)))
	(gui-add-front-rpc (. *window* :change x y w h))
	(mail-timeout (elem-get select +select_timer) +rate 0)
	(while *running*
		(defq *msg* (mail-read (elem-get select (defq idx (mail-select select)))))
		(cond
			((= idx +select_tip)
				;tip event
				(if (defq view (. *window* :find_id (getf *msg* +mail_timeout_id)))
					(. view :show_tip)))
			((= idx +select_timer)
				;timer event, re-arm and do periodic work here
				(mail-timeout (elem-get select +select_timer) +rate 0))
			;must be +select_main
			((. *window* :dispatch *msg*))
			((. *window* :event *msg*))))
	(gui-sub-rpc *window*)
	(profile-report "Template"))

Key points:

• The +select enum names the mailbox slots. Slot 0 (main) receives window events; add extra slots as needed (e.g., timer, remote) and handle them in the cond before dispatch.

• The current message is held in the global *msg*, so action handlers can inspect it, e.g. (getf *msg* +ev_msg_action_source_id).

• (. *window* :dispatch *msg*) looks up the event's target widget and its :connect event in *event_map*, then calls dispatch-action. The final clause, (. *window* :event *msg*), handles everything else at the window level.

• tip_mbox receives hover-timeout messages from the GUI; look up the hovered widget with find_id and call :show_tip.

• The window is registered with the GUI compositor via gui-add-front-rpc and unregistered on exit with gui-sub-rpc.

• Window placement: view-locate centers a window of its preferred size on screen; view-fit clamps an explicit position and size to the screen.

• The case 2 debug header selects stack frames, profiling, or debugger support. (debug-brk "name") and profile-report are no-ops unless the matching debug import is active.

widgets.inc — The Widget Tree

(enums +event 0
	(enum close max min)
	(enum undo redo rewind cut copy paste)
	(enum button_1 button_2))

(ui-window *window* ()
	(ui-title-bar *title* "Template" (0xea19 0xea1b 0xea1a) +event_close)
	(ui-tool-bar *main_toolbar* ()
		(ui-buttons (0xe9fe 0xe99d 0xe9ff 0xea08 0xe9ca 0xe9c9) +event_undo))
	(ui-stack *stack_flow* '("main" "settings") :nil
		(ui-grid *main_widget* (:grid_width 2 :color +argb_orange)
			(. (ui-button *b1* (:text "1")) :connect +event_button_1)
			(. (ui-button *b2* (:text "2")) :connect +event_button_2))
		(ui-backdrop *settings_widget* (:min_width 512 :min_height 256
				:color +argb_black :ink_color +argb_red :spacing 16
				:style :lines))))

(ui-tool-tips *main_toolbar*
	'("undo" "redo" "rewind" "cut" "copy" "paste"))

Key points:

• The +event enum groups related events. Every interactive widget gets a unique event symbol via its :connect property; that is the key used in *event_map*.

• The first event passed to ui-buttons is the radio group: it highlights which button in that toolbar is active.

• Named widgets become globals (*b1*); anonymous ones use _.

• Containers: ui-flow (with :flow_flags), ui-grid, ui-stack (tabbed views from a list of strings), and ui-scroll. Flow flags: +flow_right_fill, +flow_left_fill, +flow_up_fill, +flow_down_fill, +flow_stack_fill.

• Other common widgets: ui-textfield (:hint_text, :clear_text), ui-files (file tree selector), ui-slider, ui-label, ui-text, ui-backdrop, ui-canvas, and ui-vdu. See gui/lisp.inc for the full set.

• Use (const ...) for compile-time values and reference other widgets' properties directly, e.g. (:color (get :color *other*)).

• ui-tool-tips attaches a list of hover tips to a toolbar or stack.

Two-Pass GUI Layout & Constraint Primitives

The GUI framework renders views using a strict, non-backtracking two-pass cycle:

1. Constraint Pass (:constraint): Traverses top-down to compute the minimum required dimensions (w, h) of each widget based on content (e.g., text bounds or child count).

2. Layout Pass (:layout): Traverses bottom-up to assign final coordinates and bounds to each widget.

• Greedy Sizing & Space Absorption: Flow flags such as +flow_stack_fill and +flow_down_fill use lastw and lasth properties to absorb remaining container space.

• In custom layout containers, always ensure child bounds respect lastw and lasth to prevent clipping or improper overflow.

actions.inc — The Switchboard

;module
(env-push)

(import "./ui.inc")

(defq
*event_map* (scatter (Fmap)
	+event_close action-close
	+event_min action-minimise
	+event_max action-maximise
	+event_undo action-undo
	+event_button_1 action-button-1)

*key_map* (scatter (Fmap)
	(ascii-code "1") action-button-1)

*key_map_shift* (scatter (Fmap))

*key_map_control* (scatter (Fmap)
	(ascii-code "z") action-undo))

;module
(export-symbols
	'(*event_map* *key_map* *key_map_shift* *key_map_control*))
(env-pop)

Key points:

• The module pattern — env-push ... export-symbols + env-pop — keeps the maps local to this file's environment.

• Map values are action function names, not calls: dispatch-action evaluates the list.

• Key maps split by modifier state: plain, shift, control. Use (ascii-code "x") for characters and 0x4000xxxx hex codes for special keys (arrows, home/end).

ui.inc — The Action Handlers

(defun action-close ()
	(setq *running* :nil))

(defun action-button-1 ()
(debug-brk "button1")
	(def (. *b1* :dirty) :color +argb_red))

(defun action-minimise ()
(debug-brk "minimize")
	(bind '(x y w h) (apply view-fit
		(cat (. *window* :get_pos) (. *window* :pref_size))))
	(. *window* :change_dirty x y w h))

Key points:

• (def (. *widget* :dirty) :prop val) — the :dirty marker tells the GUI to redraw that widget on the next frame.

• Window resizes go through view-fit/view-locate then :change_dirty.

• (debug-brk "name") goes on its own line at column 0 — that is how the debugger wants to see them.

Advanced Patterns

• Single instance per node. Guard the import in app.lisp (see apps/tools/edit/app.lisp):

  (if (= 0 (length (mail-enquire "@Edit,"))) (import "./app_impl.lisp"))

• Services and RPC. Declare a service in main with (mail-declare mbox "Name" "info"), add a remote select slot for its mailbox, handle remote messages in the loop, and (mail-forget key) on exit (see apps/tools/edit/app_impl.lisp).

• Zoom. Scale font sizes with (n2i (* (n2f size) (n2f (get :zoom *window*)))), set (def *window* :zoom new_size), and rebuild the affected views (see apps/desktop/docs/ui.inc action-scale-up).

• State persistence. Save app state to a .tre file with tree-save/tree-load on a file stream (see apps/tools/edit/state.inc).

• Overloading. Import another app's ui.inc and redefun the actions you need to change (see apps/desktop/docs/ui.inc).

• Timer-driven animation. Re-arm (mail-timeout ...) on each timer tick, use +rate (/ 1000000 fps) for the period, mark changed regions with :add_dirty and widgets with :dirty (see apps/demos/boing/app.lisp).