Add fonts, autotable, autotable examples

go/vdom/ref.go

@@ -0,0 +1,55 @@
+package vdom
+
+// Ref is a handle on the real DOM node a VNode rendered to. It is the bridge the
+// neutral component code uses to ask the browser for things it cannot know on its
+// own — how big an element is, where it sits in the viewport — without importing
+// anything platform-specific: the value inside is opaque (`any`), filled in by the
+// wasm reconciler and always nil on the server. Read it through the wasmruntime
+// host API (wasmruntime.Rect, SetStyle, Focus, …), which no-ops when it is nil.
+//
+// A component creates one ref per element it needs to measure and keeps it across
+// renders (in a closure, next to its signals — NOT rebuilt inside the render
+// function, or it would be a fresh empty ref every frame):
+//
+//	panel := vdom.NewRef()
+//	return func() *VNode {
+//	    return Div(WithRef(panel), Attr("class", "…"), …)
+//	}
+//
+// and later, after the DOM exists (see wasmruntime.AfterRender):
+//
+//	r := wasmruntime.Rect(panel)   // zero Rect if unmounted or on the server
+type Ref struct{ node any }
+
+// NewRef returns an unattached Ref.
+func NewRef() *Ref { return &Ref{} }
+
+// Node is the platform DOM handle (a js.Value in the browser), or nil if the ref
+// is not currently attached to a mounted element. Component code should not need
+// this — it is for the host API and the reconciler.
+func (r *Ref) Node() any {
+	if r == nil {
+		return nil
+	}
+	return r.node
+}
+
+// Mounted reports whether the ref currently points at a live DOM node.
+func (r *Ref) Mounted() bool { return r != nil && r.node != nil }
+
+type refMod struct{ ref *Ref }
+
+func (m refMod) apply(n *VNode) { n.Ref = m.ref }
+
+// WithRef attaches a Ref to this element, so the DOM node it renders to can be
+// measured and manipulated. Ignored on the server.
+func WithRef(r *Ref) Mod { return refMod{r} }
+
+// SetRefNode points a Ref at a platform DOM handle (or nil to detach). It exists
+// for the reconciler and the host API, which live in another package; component
+// code has no reason to call it.
+func SetRefNode(r *Ref, node any) {
+	if r != nil {
+		r.node = node
+	}
+}