feat(wasm): examples/wasm-viewer, an HDF5/NetCDF-4 viewer page

Drop a file (or pass ?file=<url>&path=<object>), browse the tree lazily, see a dataset's type, shape, max shape and attributes, and page through its values as 50x12 hyperslab windows (leading dims of 3-D+ data held at chosen indices). build.sh produces pkg/ (not committed) with wasm-bindgen --target web and checks the CLI matches the crate version. test/run.sh builds it and runs test.mjs under Node against the h5py/ netCDF4 fixture (250 checks: every dataset whole and as a strided hyperslab, listings, attributes, error paths, the page's DOM-free helpers), then browser.sh renders the page in headless Chromium for eight objects and checks the DOM. The fixture gains LZ4 (read) and Zstd (refused: links C) datasets and a compound attribute (value null plus its type). ci-test.sh runs it when node and wasm-bindgen exist; the CI container has neither, so CI relies on the native h5py_interop test. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
2026-09-26 00:05:34 -05:00
parent a42b646689
commit 1abd93e0f8
11 changed files with 800 additions and 1 deletions
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+// DOM-free helpers for the viewer, so Node can test them (test/test.mjs).
+
+/** Child path of `name` in the group at `parent`. */
+export function joinPath(parent, name) {
+  return parent === "/" ? `/${name}` : `${parent}/${name}`;
+}
+
+/** One value as display text. */
+export function formatValue(v) {
+  if (v === null || v === undefined) return "";
+  if (typeof v === "bigint") return v.toString();
+  if (typeof v === "number") {
+    if (Number.isInteger(v)) return String(v);
+    return String(Number(v.toPrecision(7)));
+  }
+  if (typeof v === "string") return JSON.stringify(v);
+  if (ArrayBuffer.isView(v) || Array.isArray(v)) {
+    const items = Array.from(v.slice(0, 16), formatValue);
+    if (v.length > 16) items.push(`… (${v.length} values)`);
+    return `[${items.join(", ")}]`;
+  }
+  return String(v);
+}
+
+/**
+ * The window of a dataset to show: a hyperslab over its `shape` with the
+ * last dimension as columns, the one before as rows, and any leading
+ * dimensions held at `fixed` indices. `row`/`col` are the window's top-left
+ * corner. Returns null for a scalar (read it whole).
+ */
+export function viewWindow(shape, { row = 0, col = 0, rows = 50, cols = 12, fixed = [] } = {}) {
+  const rank = shape.length;
+  if (rank === 0) return null;
+  const clamp = (x, n) => Math.max(0, Math.min(x, Math.max(0, n - 1)));
+  if (rank === 1) {
+    const r0 = clamp(row, shape[0]);
+    const n = Math.max(0, Math.min(rows, shape[0] - r0));
+    return { start: [r0], count: [n], rows: n, cols: 1, row: r0, col: 0 };
+  }
+  const lead = shape.slice(0, rank - 2).map((n, i) => clamp(fixed[i] ?? 0, n));
+  const nr = shape[rank - 2];
+  const nc = shape[rank - 1];
+  const r0 = clamp(row, nr);
+  const c0 = clamp(col, nc);
+  const r = Math.max(0, Math.min(rows, nr - r0));
+  const c = Math.max(0, Math.min(cols, nc - c0));
+  return {
+    start: [...lead, r0, c0],
+    count: [...lead.map(() => 1), r, c],
+    rows: r,
+    cols: c,
+    row: r0,
+    col: c0,
+  };
+}
+
+/**
+ * Split row-major `data` into `rows` x `cols` cells of display text; each
+ * cell holds `per` consecutive values (the elements of an array datatype).
+ */
+export function toRows(data, rows, cols, per = 1) {
+  const out = [];
+  for (let r = 0; r < rows; r++) {
+    const row = [];
+    for (let c = 0; c < cols; c++) {
+      const i = (r * cols + c) * per;
+      row.push(per === 1 ? formatValue(data[i]) : formatValue(data.slice(i, i + per)));
+    }
+    out.push(row);
+  }
+  return out;
+}
+
+/** Number of values an array datatype packs into each element. */
+export function perElement(elementShape) {
+  return elementShape.reduce((a, b) => a * b, 1);
+}