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# Racket Wiki CMap component
This directory contains the complete browser-side CMap component.
`cmap.js` is the drawing and hit-testing engine. It is based on the
MIT-licensed ionstage/cmap 0.1.3 source and is now maintained as part of
racket-wiki. Its public additions include `onSelection` on a map and
`onActivation` and `onRendered` callbacks. Activation is recognized inside the
same hit-test and drag lifecycle as selection, so it does not depend on a DOM
`dblclick` event that may be suppressed by dragging.
`cmap-racket-wiki.js` contains the wiki-specific editor model, selection state,
content-based initial sizing, resize and relation controls, page concepts and
submap concepts. Automatic sizing remains active while text is edited and is
disabled when the user resizes a concept manually.
Selected concepts expose an edit handle. The host opens a modal editor for
their shared name, aspects, people, description page, synopsis, image, external
web address and linked wiki/CMap target, plus placement-specific background
colour and typography. The editor has one compact tab for content, links and
images, and a second tab for detailed colours, typography and submap
presentation. Detailed settings can be saved as named, wiki-wide database
styles; selected styles are applied immediately and non-default styles can be
deleted. Its action bar remains visible while a tab scrolls.
Structural kinds such as a sub-CMap head remain placement roles. Page concepts retain their linked `pageSlug`; double-click is
reserved for opening that wiki page. Concepts may alternatively retain a
`cmapSlug` for another stored CMap or a `parentCmapLink` for navigation back
from a child map. An optional `externalUrl` accepts only HTTP(S), opens in a new
browser tab and is shared by every placement of that concept. Images are data
URLs inside the persisted CMap JSON document.
Font families are selected from a practical list and font sizes are stored in
typographic points. The host can change the linked page or CMap independently
of the visible label and provides background and text-colour pickers.
Linking phrases are compact borderless nodes at the intentional bend between
two connector segments. Their position is stored with the rest of the map.
When an endpoint is deleted, a genuinely branching phrase is retained while it
still has at least one incoming and one outgoing concept. Losing the final
endpoint on either side removes the phrase and all its remaining segments.
Multiple selected items can be moved or deleted together. Grouping is a
structural operation: the editor creates an expanded sub-CMap with a named main
concept and adopts the selection as its contents. Ungrouping dissolves a
selected inline sub-CMap or moves selected child items one level outward.
`toDocument` and `loadDocument` round-trip the complete editor model: items,
formatting, positions, connectors, recursive submap membership and promoted
map references. The wiki host persists this JSON document through its CMap API.
## JSON interchange
`/js/cmap-interchange.js` implements the versioned `racket-wiki-cmap-bundle`
format. A bundle mirrors the normalized database model: `cmaps[]` contains the
complete placement and presentation document, `concepts[]` contains shared
content once per UUID, and `pages[]` contains the current Markdown, tags and
referenced attachments of linked wiki and explanation pages. Attachments retain
their MIME type and binary base64 content; import uploads them under the target
page and rewrites the Markdown to the newly allocated URL. The root CMap and every included CMap retain
their stable slug. Derived CMaps automatically include their source CMap.
Presentation includes coordinates, dimensions, colours, font settings,
sub-CMap membership, linking phrases and connectors. Connector endpoints use
local item ids; concept identity never depends on those local ids. The formal
contract is
[`racket-wiki-cmap-bundle-v1.schema.json`](../schemas/racket-wiki-cmap-bundle-v1.schema.json).
An external generator may use a temporary id such as `new:security-review` for
a new concept. Every concept must also occur in at least one non-phrase
`document.items[]` placement with coordinates. On import the server turns such
a temporary identity into a UUID through the central Racket UUID helper. UUIDs
already present in an export remain unchanged. Imported CMap slugs likewise
remain unchanged.
The editor keeps up to one hundred complete document states for Undo and Redo.
One drag or resize gesture forms one history step. The public `undo`, `redo`,
`canUndo`, `canRedo` and `resetHistory` methods are also used by the wiki host
for keyboard shortcuts and context-menu state.
`cmap.css` contains all CMap presentation and interaction styles.
The source files deliberately remain separate but form one component and are
loaded directly from `/cmap/`; there is no runtime download or vendor patch.