Nemi Canvas

A Canvas board is an infinite whiteboard. Through this connection a board is a flat list of elements drawn in order; later elements draw on top.

Elements

Every element is { type, x, y, w, h, ... } in world pixels, y growing downwards.

Common fields: stroke (hex, default #1e1e1e), fill (hex, or transparent, the default), strokeWidth (1 to 12, default 2), text (a shape's label, up to 4000 characters), dash (solid, dashed, dotted), opacity (0.05 to 1), angle (degrees). Leave id out on new elements; ids are assigned. At most 2000 elements per board.

Every update replaces the whole board

canvas_update with elements replaces everything. To change a board:

1. canvas_get (leave include_strokes false unless you must keep freehand drawings; if the board has draw elements you must set it true, or they are lost).
2. Edit the list: keep every existing element, with its id, exactly as it was unless you are changing it.
3. canvas_update with the complete list.
4. Check the returned snapshot: elements that were invalid are dropped.

Cards that point at files, documents, links or sheet data (file, docref, embed, sheetdata) come back from canvas_get; send them back unchanged.

Lay it out on a grid

Boards look deliberate when everything sits on a grid. Use these numbers unless the content needs more room:

• Box: 200 x 80, text inside via text, fill a light colour, stroke a darker one of the same hue.
• Gap: 80 between boxes horizontally, 60 vertically.
• Title: a text element at the top left, fontSize 32, bold true.
• Arrows: from the middle of one box's edge to the middle of the next. For a box at (x, y, w, h) flowing right to the next at (x2, y2): start (x + w, y + h/2), delta (x2 - (x + w), (y2 + h2/2) - (y + h/2)).

Patterns:

• Flowchart: steps left to right or top to bottom, decisions as ellipse or a rotated rect with two labelled outgoing arrows.
• Mind map: the central idea in the middle, branches on a circle around it, sub-ideas further out; line connectors.
• Timeline: a long horizontal line, events as small boxes alternating above and below, dates in text.
• Kanban: column headers as text, sticky cards stacked beneath each (200 x 120, gap 20).
• Retro or brainstorm wall: one sticky colour per category, with a text legend.

Soft colours read well together: yellow #FFF3B0, green #D9F2C4, blue #D6E8FF, pink #FFD9E6, purple #E6DDFF, orange #FFE0C2, with dark text.

Create

1. canvas_create with a title.
2. Work out every coordinate first, then canvas_update with the whole element list in one call.
3. Reply with what you drew in a sentence. If the client shows the board, do not describe it element by element.

Read

canvas_get and read the text and sticky elements to know what the board says. Group what you find by position (columns, clusters) when summarising a wall of notes.

Delete

canvas_delete is permanent. Confirm first.