# Sedona SAX Tree View Viewer & Program Editor A Tkinter desktop editor for Sedona Framework application files (`.sax`). It shows the component hierarchy as a navigation tree, paints the selected folder's children as a wiresheet of draggable component boxes, draws the links between them, and writes box positions back into each component's `meta` property on save. Current version: **0.0.0.051** (see [Versioning](#versioning)). ## Requirements Python **3.13 from Homebrew**, which brings Tk 9: ```bash brew install python-tk@3.13 ``` Do **not** run this with `/usr/bin/python3`. Apple's system Python ships Tk 8.5.9, a 2010 build that is broken on current macOS: windows open at the right size with the right titles, but no widget contents ever paint. A blank white panel is the symptom, and it looks exactly like a layout bug in this code. It isn't. Verify which Tk an interpreter has: ```bash /opt/homebrew/bin/python3.13 -c "import tkinter; r=tkinter.Tk(); print(r.tk.call('info','patchlevel'))" ``` ## Running ```bash cd sedona_editor /opt/homebrew/bin/python3.13 run.py ``` On first launch, set **Sedona home folder** in the Preferences menu — the directory containing `manifests/` and `kits/`. Nothing will load until it is set. Preferences are stored in `editor.properties`, read from the current working directory. On macOS the menu bar (File / App / Preferences) appears at the **top of the screen**, not inside the window. Tk always hands it to the system menu bar. ## Module layout | Module | Responsibility | Needs a display | |---|---|---| | `app_state.py` | Preferences, runtime state, widget handles, `mark_dirty`/`mark_clean` | no | | `sax_dom.py` | `meta` bit-packing codec, component path resolution | no | | `schema.py` | Kit manifest loading, slot inheritance, slot visibility rules | no | | `undo.py` | Undo/redo stack of reversible DOM commands | no | | `wiresheet.py` | Grid, component boxes, link routing and painting | yes | | `properties.py` | The Properties view: every slot of one component, read and written | yes | | `sax_file.py` | Open/save, navigation tree, cascading delete | yes | | `main.py` | Widgets, menus, event handlers, dialogs, main loop | yes | | `run.py` | Entry point | yes | Imports form a DAG — `sax_dom`/`schema` depend on nothing UI-shaped, `wiresheet` and `sax_file` build on them, `properties` builds on `schema` and `undo`, and `main` wires it together. Event handlers live in `main`, which is what keeps the graph acyclic. ### Shared state Modules reach shared state as **`app_state.`**, always qualified. A bare `from app_state import is_dirty` would bind a copy, so a later rebinding would be invisible to every other module. Every mutation of "the document changed" goes through `app_state.mark_dirty()`, which also applies the unsaved-state pink canvas tint. ### Undo and keyboard shortcuts `undo.py` holds a stack of commands that own their DOM mutation in both directions: `MetaMoveCommand` (a box drag, or a whole Tidy Layout as one step), `AddComponentCommand` (which also removes the `` entry placing it may have added) and `DeleteComponentCommand` (which restores the removed `` entries at their original indices, reinserting in ascending order so the indices stay valid) and `SlotValueCommand` (one Save from the Properties view, however many slots it changed). Nothing in `undo.py` touches Tk; `main` registers a refresh callback at startup, which is what keeps `sax_file` and `wiresheet` free to push commands without an import cycle. Undoing back to the depth of the last save clears the dirty tint rather than leaving it lit. | Shortcut | Action | |---|---| | `Ctrl`/`Cmd` + `S` | Save (direct overwrite) | | `Ctrl`/`Cmd` + `Z` | Undo | | `Ctrl`/`Cmd` + `Y` or `Ctrl`/`Cmd` + `Shift` + `Z` | Redo | | `Del` / `Backspace` | Delete selected component | | `Ctrl`/`Cmd` + `B` | Show or hide the tree/palette column | | `Ctrl` + `W` | Tidy Layout: re-flow the open sheet | | `Alt` + `Left` / `Alt` + `Right` | Back and forward through the sheets opened this session | | `Ctrl`/`Cmd` + `+` / `-` | Zoom the sheet in and out | | `Ctrl`/`Cmd` + `0` | Zoom back to 100% | | `Ctrl`/`Cmd` + `9` | Zoom to Fit: show the whole sheet | | `Ctrl` + wheel | Zoom around the pointer | Both `Command-` and `Control-` are bound for each, so the same build works on macOS and Windows; menu accelerators render as `Cmd` or `Ctrl` per platform. Tidy Layout is the exception, on `Control-` alone: `Cmd` + `W` closes the window on macOS. ### The View menu **Tree / Palette** hides the left column so the wiresheet has the whole window, and puts it back at its configured width. ttk has no hide flag for a pane, so the column is dropped from the paned window and re-inserted at the front. **Zoom In**, **Zoom Out** and **Zoom 100%** step a ladder of scales from 25% to 300%, with the zoom buttons, the percentage and the fit icon sitting beside the navigation arrows in the toolbar. **Zoom to Fit** is the one thing that lands between the ladder's rungs -- a sheet fits at whatever scale it fits at -- and stepping in or out from there rejoins the ladder. It measures the sheet from item coordinates rather than `canvas.bbox()`, which is inflated by the outline stroke: a stroke is the same two pixels at every zoom, so a bbox divided back to 1:1 reports a slightly smaller sheet the further in it is zoomed, and fitting an already fitted sheet would creep instead of standing still. Anything painted left of or above the canvas origin is measured from the origin instead, since no amount of scrolling can bring it into view. The sheet is painted and routed at 1:1 -- box metrics, wire stubs, lane gaps, clearances and knob radii are all tuned in those pixels -- and `apply_sheet_zoom` scales the finished picture, so a zoomed sheet keeps exactly the proportions of a 1:1 one and the router makes the same decisions at every scale. Text scales because the three box fonts are resized after the boxes were measured with them. `redraw_links()` is what a drag or a drop calls: it puts the boxes back to 1:1 for the routing pass and scales the result again, since the router reads box positions straight off the canvas. Canvas coordinates therefore carry the zoom, which is why the drag, release and drop handlers snap against `meta_scale * zoom`. **Back** and **Forward** walk the sheets opened this session, mirrored by the two arrow buttons in the toolbar. The history records the element whose children are painted -- the same thing `app_state.current_sheet_parent` holds -- rather than a tree item id, because rebuilding the tree hands out fresh ids while the elements themselves survive. Opening a different file retires the history; a delete or an undo drops only the entries whose element has left the document, keeping the position on screen. Walking the history drives the tree selection, which is what paints the sheet, and is suppressed from recording so a walk cannot rewrite the trail it is following. ### The component popup Right-clicking a component offers the same actions from the wiresheet and from the navigation tree -- Properties, Delete Component, Link Mark, and Link From / Link To naming the marked component once one is marked. `fill_component_popup` builds both, and its entries close over the component rather than reading a selection back, which is what lets each popup act on the row or box that was actually clicked. The tree's root row keeps its own popup. ### The Properties view **Properties**, from either component popup, **takes over the editor pane** -- the sheet and the slot table are the same piece of screen, so only one of them is ever the thing being looked at. The canvas is unpacked, never destroyed, so it keeps its items and its scroll position and **Close** puts it back exactly as it was. It is still painted while it is hidden, which costs nothing and means there is no catching up to do when it returns. Choosing a node in the tree means "show me that sheet", so it stands the view down rather than leaving the selection looking like it did nothing. So does deleting the component it is showing, from anywhere -- every delete in the UI goes through `delete_component`, because `sax_file` does its own view refresh rather than going through `refresh_all_views`. It lists every slot the manifest declares -- bar one kind, see **Hidden slots** below -- in manifest order, each row numbered with the same slot id the wiresheet box uses. The box's visibility rules do not apply here: they are right for a diagram and wrong for the one place a value is meant to be changed, so `HvacControl` shows all 47 rows rather than the 8 its box paints. The header names the component, its type and its **absolute path** -- the same path a `` writes, and the one thing on screen that separates this `Cascade` from the three others in the file. It is read from the document rather than held, so a renamed parent shows up on the next Refresh. Each row carries the slot's declared type between its name and its value, written the way a slot sheet writes it: the manifest stores the primitives bare and everything else already qualified, so `int` is shown as `sys::int` and `sys::Buf` is left as it stands. Which rows can be typed into is the slot's own business, not the view's: | Slot | Field | |---|---| | config (`c` flag) and not `@readonly` | white, editable | | everything else | grey, read-only | A runtime slot holds a live value that no offline file carries, so nothing here could usefully write one; a `@readonly` config slot is the manifest saying the same about a value that *is* persisted. Both read the same way on screen. A **dropdown is offered only where there is a choice to make**. A read-only bool or enum gets a plain field instead, since a disabled dropdown is an arrow that does nothing -- and a read-only bool is still filled by its state, because a runtime bool has a state too. The dropdown is a `tk.OptionMenu` rather than a `ttk.Combobox`, for one reason: on the Windows themes a Combobox draws its field with a native element and **ignores `fieldbackground` outright**, so a bool could never be filled with its colour. The plain Tk widget takes the colour it is given. It reports a change through its variable rather than an event, which also catches a value set from anywhere else -- and means loading a row looks exactly like choosing one, so the load is flagged and the tint left alone until every row is in. Each row is drawn from the slot's facets, so it reads the way the kit author meant it to: - `@trueText` / `@falseText` turn a bool into its own two words -- `Disabled` / `Enabled` rather than false / true -- and **the field is filled by the state**: green for true, red for false, blue for null. It began as a coloured dot beside the field, which meant learning what the dot stood for, then as coloured text; a block of colour carries down a long list of slots where a letterform does not, and the words stay black so they read as easily as every other value. Dropping the dot also let a bool's field line up with the numbers above and below it. - **Null is a value, not an absence.** Sedona models it as NaN for a float and a sentinel for the integer types, and a config slot can genuinely hold it: `control::WriteFloat` pairs an `in` property with a `setNull` action, and the sample app carries `` on four of them. So `null` shows against a blue dot, types back in as `null`, and reads as `@nullText` where a kit declared one -- `ontrolBaseDriver::DeviceNetwork.status` calls it `Disabled`. `@allowNull false` is the one case that refuses it, and takes it out of a bool's dropdown. - `@range` turns an integer slot into a named dropdown; the file still stores the index. - `@precision` fixes how many decimals a float shows, `@unit` puts the symbol after the field (`celsius` reads `°C`). - `@min` / `@max` bound what Save will accept, and are shown as `[0 - 1000]`. A row prints a range when the manifest declared one, and otherwise only where the **type** supplies a narrow one: `byte` reads `[0 - 255]` and `short` reads `[0 - 65535]` unfaceted, because those bounds are worth knowing. An `int`, a `long` or a float prints nothing, since its full span means no more than "a whole number" and crowds the row to say it -- and an end those types leave undeclared prints as `-inf` / `+inf` rather than reaching for the type. This is display only: Save still holds every integer to its type, so an `int` of `9999999999` is rejected whether or not its row advertised the limit. - On a **`Buf`** those same two facets count *characters*, not magnitude, and the count is what the buffer can hold: `TcpDevice.ipAddr` is a `Buf(17)` declaring `@max 16`, the seventeenth byte being the null terminator. The row reads `[max 16 chars]` and Save refuses a longer string -- overrunning a Buf is not a display problem, the device gets a string it has no room for. The value shown is the file's ``, or the manifest default when the file carries none, or the type's zero when the manifest declares none either. Runtime slots reach the view through that second and third step, which is why they read `0.0` here and `null` on the wiresheet: the box is reporting what the file says, and this is reporting what the device would start from. `meta` gets a row of its own rather than an editable integer: typing 822411269 into a field is no way to set either of the two unrelated things it packs. The `»` beside it opens them apart -- the four user group bits as checkboxes, and the position as x and y, which a drag would otherwise be the only way to set. Both are in grid units, the figure `meta_scale` multiplies to reach pixels, and each is one byte, so the editor holds them to 0-255. The row shows the groups it summarises and the position beside them. Saving a changed meta writes the position first and the groups second, because each pass preserves what the other owns: the position pass keeps the group bits it reads, and the group pass keeps the position it was just handed. The table is laid out at its natural width and never stretched. Every widget is gridded straight into one frame, so grid's own column sizing is what lines the four columns up across the rows, and no column carries a weight -- widening the view shows more white to the right of the table instead of walking the fields across it, and narrowing it scrolls sideways rather than squeezing them. Each scrollbar appears only while it has somewhere to scroll; `Shift` + wheel scrolls sideways. ### The file name goes red While anything is unwritten, the file name on the tree's **root row** turns `DIRTY_NAME_COLOUR`. That row is the only place a file name appears on screen -- a Tk window title cannot be coloured. The tag's colour is configured **once**, when the tree is built, and never changed; what moves is whether the row carries the tag. Reconfiguring a tag does not reliably repaint rows that are already drawn, so a version that recoloured the tag went red only on the paths that happened to rebuild the tree -- a Properties Save did, dragging a box did not, and the two disagreed in a way that looked like the drag was not marking anything dirty at all. Setting a row's tags repaints that row, so the colour cannot fall behind the state. `anything_unwritten()` is the whole rule, and it counts **both**: the document being dirty, and the Properties view holding edits its Save has not been pressed for. A typed value is as unwritten as a dragged box, and a name that only went red for the second of those would be telling half the story. So it goes red the moment a field is edited, before anything has reached the document, and comes back when the edit is typed away, discarded, or saved and written. The navigation tree runs on a style of its own, `NAV_TREE_STYLE`, for one reason: a themed Treeview maps the selected state to `SystemHighlightText`, and **that mapping beats a row tag's own foreground**. The name turned white-on-blue the moment its row was selected -- which is exactly when the root sheet is the one being looked at, so the red was invisible in the most ordinary case. The style drops the selected foreground entry altogether and takes a light selection background instead, so a tag's colour shows in every state and plain black still reads on the highlight. Scoped to this tree, so the palette keeps the system selection. `app_state.refresh_dirty_display()` is the single funnel, called from `mark_dirty` and `mark_clean` through a callback `main` registers -- the same shape `undo` uses for its view refresh, and what keeps `app_state` free of any idea that a Properties view exists. ### Hidden slots `@hidden` is the one facet the view filters on, and only by default. niagara.html says hidden slots "are designed to be invisible to the user" and that interfaces should rarely display them; every one under Sedona home is a `void` action a kit uses internally, such as `HdwAI.checkType`. A **Hidden slots (n)** checkbox in the footer brings them back, and the answer sticks for the session rather than being asked again for every component. The rows are always built -- the checkbox `grid_remove`s and re-`grid`s them, which keeps each widget's options so putting a row back needs no arithmetic, and an emptied grid row collapses rather than leaving a gap. The checkbox itself only appears on a type that has something to reveal, so most components carry no control for a thing they do not have. ### Unsaved edits in the Properties view An edited field paints the whole view in **`app_state.DIRTY_TINT`** -- the same colour the canvas wears when the file is dirty, now one constant rather than two spellings of `#ffe6e6`, so "there is something here you have not written yet" looks the same wherever the change was made. The fields themselves keep their own white or grey: whether a value *can* be typed into is a different thing from whether it *has* been. Dirtiness is read from the widgets rather than tracked as a flag, so typing a value and then typing it back leaves the view clean -- it is exactly the set of rows Save would write. The tint follows the fields live, and comes off on Save and on Refresh. Every way of leaving the view goes through `close_properties`, so the question is asked once, in one place: **Close**, picking another sheet in the tree, walking **Back** or **Forward**, or right-clicking a different component. The box has three answers rather than two, because "I did not mean to leave" and "leave, I did not want those edits" are different things and a two-way box makes the user guess which one Cancel is. A Save that fails its range checks keeps the view open, since leaving then would discard exactly the values being complained about. Refusing to leave has to put the tree back on the sheet that is still showing. The **element** is held for that, not the tree item id, for the same reason the history holds elements: a rebuild of the tree hands out fresh ids. ttk queues its selection event rather than dispatching it, so the flag that stops the restoring selection being read as a fresh choice is cleared from an `after_idle` rather than inline. Nothing asks when the question has nowhere to go -- the component deleted, a different file opened. Those go straight to `dismiss_properties`, which is also what the panel's own Close calls once the question has been put and answered. Discarded edits are discarded: the panel is destroyed, and the next one is built from the document, so it opens on the file's values with no tint. **Save** writes the edited rows into the DOM and pushes them as **one** undoable step, so a dozen changed slots undo together. Only rows whose text actually moved are written, so a component keeps exactly the props the file gave it plus the ones edited here -- and if any edited row fails its range check, *nothing* is written and the view names every offending row at once. Save changes the document, not the file; `Ctrl`/`Cmd` + `S` still writes the `.sax`. **Refresh** re-reads every row from the DOM, discarding pending edits, which is also how the view catches up after an undo. `Del` and `Backspace` are bound application-wide, so they also reach a field being typed in. `delete_selected_component` therefore ignores the key while the Properties view is up, while focus is in another window, and while it is in any widget that owns the keyboard -- an `Entry`, a `TCombobox`, a `Text`. A backspace aimed at a text field must never delete a component. Save still checks the component is in the document before writing, since an undo can take it out from under the view. ### Following a link to its other sheet Right-clicking a wire or a knob offers **Go to Link Wire Sheet ""** alongside Delete Link, naming the sheet the far end of that link is on -- the end a grey knob stands in for. The entry is left off a link with both ends on the open sheet, which has nowhere to go. `find_component_by_path` in `sax_dom` turns a ``'s from/to reference back into the component it points at, the inverse of `get_component_path`, and the sheet is that component's parent; a parent of `` is the file's root node, which the popup names after the file. The jump selects the same link again once it arrives. It has to be found by its element rather than by the tag it was picked on, because a repaint hands out fresh wire tags, and it has to wait for that repaint: ttk queues its selection event rather than dispatching it, so the sheet is not painted at the point the tree node is selected -- and painting a sheet clears whatever link was selected. The selection is therefore made from an `after_idle` callback, and the link is scrolled to the middle of the view. Arriving is an ordinary sheet opening, so **Back** returns to the sheet the link was picked on. ### Testing without a window `app_state`, `sax_dom`, `schema`, `undo` and `wiresheet` import with no display, so the rules can be exercised directly: ```python import xml.etree.ElementTree as ET import app_state, schema, wiresheet app_state.SEDONA_HOME = "../sedona" app_state.xml_root_element = ET.parse("../DDC_8-ATP_PION_17.sax").getroot() schema.load_schema_kits_and_manifests() idx = wiresheet.build_linked_slot_index() print(schema.get_slots_for_type("ontrolControl::HvacControl", idx.get("/AHU20_1/TmpCont/HvacCon", ()))) ``` ## How it reads a Sedona app ### Manifests Each `` in the file's `` block is resolved to `/manifests//-.xml`, falling back to the highest-sorting file in that directory when the checksum is absent. Slots are flattened along the `base` chain, so inherited slots keep their declaration order. A kit with no manifest aborts **that load only**. `schema.load_schema_kits_and_manifests()` raises `schema.MissingManifestError` naming every unresolved kit at once, the caller shows a dialog asking the user to check the Sedona home folder, and `sax_file.reset_to_startup_state()` returns the app to its just-launched state — no file, empty tree, empty sheet. The app stays open, so the folder can be corrected in Preferences and the file opened again. The same error raised while placing a palette component only abandons that placement: the `` entry just added to `` is removed and the previous registry is rebuilt. ### Slot visibility A component type can declare far more slots than are worth seeing; `HvacControl` has 47. Rows are filtered by these rules, in precedence order: | Precedence | Condition | Result | |---|---|---| | 1 | Slot appears in `` (either end) | **Show** — overrides everything below | | 2 | `` facet | Hide | | 3 | Runtime slot (no `c` in `flags`) | **Show** | | 4 | Config slot (`c`), unlinked | Hide | | 5 | `o` flag (operator) | Hide | Rule 1 outranks rule 2 deliberately: a linked slot with `@summary false` still needs a row for its wire to terminate on, otherwise the wire points at the box's centre. Row numbers are the manifest slot ids, so hidden rows leave **gaps** in the numbering (`01, 02, 03, 04, 05, 08, 11...`) rather than renumbering. The numbers stay meaningful against the manifest. Consequence worth knowing: `meta` is a config slot that nothing links to, so it is hidden from every box. It holds the packed position, not process data. ### Why outputs read `null` Config slots carry `flags="c"` and are persisted in the `.sax`. Runtime slots carry no flag and are **never** persisted — they only exist on a live device. So `out` and `in` have no `` in the file and the renderer substitutes the string `null`. That is correct for an offline app dump, not a fault. ### The `meta` property A packed 32-bit integer, decoded in `sax_dom.py`: ``` bits 31-24 x position, in grid units bits 23-16 y position, in grid units bits 15-8 reserved (preserved verbatim on write) bits 7-0 user group bits 1-4 in the low nibble, reserved high nibble ``` Writes re-encode only x and y and preserve every other bit, so dragging a box never disturbs the rest of the value. ### Links `` sits at the document root, with `from`/`to` references of the form `/path/to/Component.slotName`. - Both endpoints on the current sheet → an orthogonal wire is routed **around** the boxes. Routing tries a clear vertical channel between the two boxes first, then a lane above or below everything (which is what feedback links right-to-left need), and only falls back to a direct dog-leg if nothing is clear. - One endpoint off-sheet → a **knob** is drawn at the slot's edge, marking a connection that leaves this sheet. In the sample app, 137 of 217 links are same-sheet, so knobs are not a rare case. Wires and knobs are painted behind the component boxes and re-routed on every drag step, since they are not part of the dragged canvas group. ### Facets this does not act on Read against `SedonaDoc/niagara.html`, which is what tells Niagara -- and so this view -- how to model a slot. These are recognised there and deliberately not acted on here: | Facet | Where it is used | Why not | |---|---|---| | `fieldWidth` | 3082 slots | A per-slot column count for the text field. Applying it would make the value column ragged; a table reads better with one width. | | `radix`, `showSeparators`, `multiLine`, `fieldEditor` | unused by any kit under Sedona home | Nothing to render. | And two things worth knowing about the manifests themselves rather than the code: - 24 slots declare **`readOnly`** with a capital O. Niagara matches flag names exactly, so it is not the `readonly` flag and does nothing there either -- it is stored as an ordinary facet. Every one of them is a runtime slot, so they are already grey here for the other reason, and honouring the typo would change nothing on screen. - 118 **config `Buf`** slots omit `@asStr`, so by the letter of `components.html` they serialise as base64 rather than text. Their names (`text`, `trueText`, `buttonText`) say otherwise, so they are edited as text here. ## Versioning `VERSION` lives in `app_state.py` and is shown in the window title. - **Feature** → bump the version. - **Bug fix** → no bump. - **Refactor with no behaviour change** → no bump. ## Known gaps - The yellow square in each box header is drawn but wired to nothing; it is the natural place for a per-box collapse/expand toggle. - Undo covers box moves, adds and deletes. Nothing else pushes a command, so a change made outside those three is not reversible. - `on_canvas_release` snaps using the rounded-rectangle polygon's first coordinate, which is `x1 + radius` rather than `x1`, so snapping is offset by the corner radius. - Slot values are edited from the Properties view only; a wiresheet box row is still display-only.