spaday-dagre 0.2.2

dagre graph rendering for spaday

Overview

spaday-dagre renders directed graphs in spaday from a serializable node/edge config, laid out by @dagrejs/dagre and drawn as light-DOM SVG. Colors ride the spaday shell's --spa-* tokens, so bind_root_class("wa-dark", ...) re-themes the graph with the rest of the page, and application CSS reaches every shape. dagre-node-click bubbles {id, label, x, y} and dagre-edge-click bubbles {source, target, label, x, y} — the graph context plus the pointer position — so SetField("selected", event_value("id")) selects and open_popup(..., x=event_value("x"), y=event_value("y")) positions. Right-clicking a node or edge bubbles dagre-node-contextmenu / dagre-edge-contextmenu with the same shape, pairing with spaday's open_popup for context menus.

Navigation is dagre-d3-class: cursor-anchored wheel zoom, drag pan (clamped so the graph can never be dragged out of view), double-click reset, and an optional GitHub-mermaid-style D-pad (controls) with pan arrows around a center reset circle.

The host draws into an absolutely positioned frame and contributes no intrinsic height: give <spaday-dagre> or an ancestor an explicit height (e.g. style="height: 32rem"). An unsized host falls back to the graph's natural height, with a one-time console warning.

Quick example

from spaday import element
from spaday.backends.starlette import serve
from spaday_dagre import Dagre, package

graph = Dagre(
    graph={
        "nodes": [{"id": "a", "label": "Alpha"}, {"id": "b", "shape": "diamond"}],
        "edges": [{"source": "a", "target": "b", "label": "flow"}],
    },
    layout={"rankdir": "LR"},
    controls=True,
)
app = serve(element("main").child(graph), packages=[package])

Node sizes default from label measurement; per-node width/height/class/shape (rect, diamond, ellipse) and per-edge label/class override. The maxLabelWidth prop (px) caps label-driven width: wider labels are ellipsized, with the full label as a native tooltip. layout passes through to dagre (rankdir, align, nodesep, ranksep, edgesep, marginx/marginy, ranker). Installing the package registers the dagre entry point, so packages=["dagre"] also works.

A node with parent nests inside the cluster named by another node's id (dagre's compound layout): the cluster renders as a rounded container behind its children, labeled along its top edge, and clicks/right-clicks on it dispatch the node events with the same detail shape. Parentless nodes mix freely with clustered ones; graphs without parents keep the flat layout path.

The emphasis prop (a list of node ids; a single id string works too, null clears) toggles the .emphasis class on the matching rendered nodes by pure class reconciliation — no re-layout, no graph rebuild — and re-applies after re-renders, so a live selection binds directly: .bind("emphasis", "selected"). The focusNode(id) method (declared in the manifest for spaday's Invoke) pans — and zooms to a comfortable level when needed — so the node or cluster is centered in the view; the bindable focus prop is a property spelling that calls it on set, with the method as the primary API.

Theming

Component-scoped tokens layer over the shell's --spa-* tokens, so an application can theme the graph from the host (or any ancestor) without knowing its internals — a token set once wins in both light and dark page modes:

Node and edge class values are forwarded onto the rendered <g> groups (alongside spaday-dagre-node / spaday-dagre-edge), so custom classes are CSS-targetable directly. One variant is built in: a node or edge whose class includes emphasis gets an accent outline.

Run the local example

python -m spaday_dagre.example

Open http://127.0.0.1:8016: a pipeline DAG live over a transports wire — the server sweeps an active-stage highlight through the graph while node/edge selection rides back as model edits — with direction switching, mixed node shapes, a "modeling" cluster grouping the middle stages, selection mirrored into the emphasis prop, a right-click menu for nodes and edges (its Focus item centers via focusNode), view controls, and the dark-mode toggle.

[!NOTE] This library was generated using copier from the Base Python Project Template repository.