Keep the Draw control and its chosen shape across engine switches

The session Draw handle keeps the shape and colour and the marks stay on the annotation board; the drawing tool (preview, click handler, Escape and Enter keys) belongs to the attached viewer, so a switch ends an open sketch and gives the pointer back.

src/annotations/drawTool.js

@@ -76,6 +76,8 @@ export function initDrawTool({
   navigation = null,
   publish = () => {},
   connect = () => () => {},
+  initialShape = 'area',
+  initialColor = 'primary',
 }) {
   // A page without the Draw controls (the Display controls view omitted) has
   // no draw tool.
@@ -85,8 +87,8 @@ export function initDrawTool({
   let active = false;
   let destroyed = false;
   let session = null;
-  let shape = 'area';
-  let color = 'primary';
+  let shape = normalizeShape(initialShape);
+  let color = DRAW_COLORS.includes(initialColor) ? initialColor : 'primary';
   let hint = '';
   let handler = null;
   let lease = null;
@@ -494,6 +496,9 @@ export function initDrawTool({
     get shape() {
       return shape;
     },
+    get color() {
+      return color;
+    },
     get session() {
       return session;
     },
@@ -587,6 +592,110 @@ export function initDrawTool({
   return api;
 }
 
+/**
+ * The Draw control for the page session. The marks live on the annotation
+ * board and the chosen shape and colour here; the drawing tool itself (its
+ * preview, click handler and Escape/Enter keys) belongs to the attached
+ * Cesium viewer. `attachScene({ viewer, navigation })` starts the tool on a
+ * viewer with the shape and colour last chosen; `detachScene()` ends it, an
+ * open shape included. Without a viewer the controls answer nothing, as on
+ * an engine without Draw. Same handle as initDrawTool's
+ * (`window.__gevDrawTool`), kept across switches.
+ */
+export function createSessionDrawTool({
+  annotations,
+  navigation = null,
+  publish = () => {},
+  connect = () => () => {},
+}) {
+  if (!annotations || !document.getElementById('draw-toggle')) return null;
+  let inner = null;
+  let shape = 'area';
+  let color = 'primary';
+  let destroyed = false;
+  let settled = Promise.resolve();
+  const detachScene = () => {
+    if (!inner) return settled;
+    shape = inner.shape;
+    color = inner.color;
+    const previous = inner;
+    inner = null;
+    settled = previous.destroy();
+    if (window.__gevDrawTool === previous) window.__gevDrawTool = wrapper;
+    return settled;
+  };
+  const wrapper = {
+    get active() {
+      return inner?.active ?? false;
+    },
+    get shape() {
+      return inner?.shape ?? shape;
+    },
+    get color() {
+      return inner?.color ?? color;
+    },
+    get session() {
+      return inner?.session ?? null;
+    },
+    get attached() {
+      return Boolean(inner);
+    },
+    setActive: (next) => inner?.setActive(next) ?? false,
+    setShape(next) {
+      shape = normalizeShape(next);
+      inner?.setShape(next);
+    },
+    setColor(next) {
+      color = DRAW_COLORS.includes(next) ? next : 'primary';
+      inner?.setColor(next);
+    },
+    marks: () => presentDrawMarks(annotations.list?.() || []),
+    flyToMark: (id) => inner?.flyToMark(id) ?? false,
+    addVertex: (...args) => inner?.addVertex(...args) ?? false,
+    finish: () => inner?.finish() ?? Promise.resolve(null),
+    cancel: () => inner?.cancel(),
+    clearAll: () => (inner ? inner.clearAll() : annotations.clear?.()),
+    shapes: DRAW_SHAPES,
+    diagnostics: () =>
+      inner?.diagnostics() ?? {
+        active: false,
+        destroyed,
+        sceneHandler: false,
+        domListeners: 0,
+        previewDataSources: 0,
+        previewEntities: 0,
+        pointerOwner: pointerOwner(),
+      },
+    whenSettled: () => inner?.whenSettled() ?? settled,
+    attachScene({ viewer = null, navigation: next = navigation } = {}) {
+      if (destroyed) return;
+      detachScene();
+      navigation = next;
+      if (!viewer) return;
+      inner = initDrawTool({
+        viewer,
+        annotations,
+        navigation,
+        publish,
+        connect,
+        initialShape: shape,
+        initialColor: color,
+      });
+      window.__gevDrawTool = wrapper;
+    },
+    detachScene,
+    destroy() {
+      if (destroyed) return settled;
+      const done = detachScene();
+      destroyed = true;
+      if (window.__gevDrawTool === wrapper) delete window.__gevDrawTool;
+      return done;
+    },
+  };
+  window.__gevDrawTool = wrapper;
+  return wrapper;
+}
+
 /** How many draw previews are attached — more than one means a leaked tool. */
 function countPreviewDataSources(viewer) {
   const sources = viewer?.dataSources;

src/annotations/drawTool.test.mjs

@@ -23,21 +23,22 @@ test('the application composition wires the draw tool and owns its teardown', ()
   const tools = read('src/app/tools.js');
   const engineAt = tools.indexOf('const annotations = sessionAnnotations({');
   const drawAt = tools.indexOf(
-    'const drawTool = initDrawTool({\n    viewer,\n    annotations,\n    navigation: styleManager,\n    publish: (view) => displayStore.publishDraw(view),',
+    "const drawTool = sessionTool(layerSession, 'draw', defer, () =>\n    createSessionDrawTool({\n      annotations,\n      navigation: styleManager,\n      publish: (view) => displayStore.publishDraw(view),",
   );
   assert.ok(engineAt >= 0, 'the session annotation board is missing');
   assert.ok(
     drawAt > engineAt,
-    'initDrawTool must follow the annotation board and receive it',
+    'the draw tool must follow the annotation board and receive it',
   );
   assert.match(
     tools,
-    /import \{ initDrawTool \} from '\.\.\/annotations\/drawTool\.js';/,
+    /import \{ createSessionDrawTool \} from '\.\.\/annotations\/drawTool\.js';/,
   );
-  // The tool holds a pointer claim, DOM listeners and a data source, so the
-  // application lifetime disposes it — not whoever last pressed the button.
-  const deferAt = tools.indexOf('defer(() => drawTool?.destroy());');
-  assert.ok(deferAt > drawAt, 'the shell must defer the draw tool teardown');
+  // The tool holds a pointer claim, DOM listeners and a data source on the
+  // viewer, so the viewer's attachment ends it — not whoever last pressed the
+  // button; the session tool ends with the page.
+  const detachAt = tools.indexOf('defer(() => drawTool?.detachScene());');
+  assert.ok(detachAt > drawAt, 'the scene must end the draw tool');
 });
 
 test('the engine resolves manual geometry before any name resolution', () => {

src/annotations/drawToolBehaviour.test.mjs

@@ -5,7 +5,7 @@
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
 import * as Cesium from 'cesium';
-import { initDrawTool } from './drawTool.js';
+import { createSessionDrawTool, initDrawTool } from './drawTool.js';
 import {
   isPointerFree,
   pointerOwner,
@@ -68,9 +68,17 @@ class FakeElement {
   }
   closest(selector) {
     // Only what the tool asks: "am I inside an activatable control?"
-    const activatable = ['button', 'a', 'select', '[role="button"]', '[role="radio"]'];
+    const activatable = [
+      'button',
+      'a',
+      'select',
+      '[role="button"]',
+      '[role="radio"]',
+    ];
     if (!activatable.some((part) => selector.includes(part))) return null;
-    return this.tagName === 'BUTTON' || this.tagName === 'A' || this.tagName === 'SELECT'
+    return this.tagName === 'BUTTON' ||
+      this.tagName === 'A' ||
+      this.tagName === 'SELECT'
       ? this
       : null;
   }
@@ -175,7 +183,14 @@ function fakeViewer() {
 }
 
 function fakeAnnotations() {
-  const calls = { annotate: [], clear: 0, restyle: [], setHidden: [], frame: [], remove: [] };
+  const calls = {
+    annotate: [],
+    clear: 0,
+    restyle: [],
+    setHidden: [],
+    frame: [],
+    remove: [],
+  };
   const marks = [];
   const listeners = new Set();
   const changed = () => listeners.forEach((listener) => listener());
@@ -223,7 +238,7 @@ function fakeAnnotations() {
 }
 
 /** Stand up a tool against fresh doubles, with globals restored afterwards. */
-function harness({ navigation = null } = {}) {
+function harness({ navigation = null, session = false } = {}) {
   resetPointerOwnership();
   const { byId, documentDouble } = fakeDom();
   const viewer = fakeViewer();
@@ -235,8 +250,7 @@ function harness({ navigation = null } = {}) {
   const shown = { view: null };
   // The controls' actions, as the display store holds them.
   const controls = { actions: null };
-  const tool = initDrawTool({
-    viewer,
+  const options = {
     annotations,
     navigation,
     publish: (view) => (shown.view = view),
@@ -244,7 +258,11 @@ function harness({ navigation = null } = {}) {
       controls.actions = actions;
       return () => (controls.actions = null);
     },
-  });
+  };
+  const tool = session
+    ? createSessionDrawTool(options)
+    : initDrawTool({ viewer, ...options });
+  if (session) tool.attachScene({ viewer });
   return {
     tool,
     shown,
@@ -299,7 +317,11 @@ test('Draw refuses to start when something else holds the pointer', async () =>
       h.shown.view.hint,
       'Directions is using the pointer — close it first.',
     );
-    assert.equal(h.tool.diagnostics().sceneHandler, false, 'no handler was bound');
+    assert.equal(
+      h.tool.diagnostics().sceneHandler,
+      false,
+      'no handler was bound',
+    );
 
     releasePointer(other);
     h.act('toggleDraw');
@@ -341,7 +363,10 @@ test('both stock viewer click actions are borrowed for the session and given bac
     const stockClick = () => 'viewer picks and selects';
     const stockDouble = () => 'viewer tracks';
     h.viewer.screenSpaceEventHandler.setInputAction(stockClick, LEFT_CLICK);
-    h.viewer.screenSpaceEventHandler.setInputAction(stockDouble, LEFT_DOUBLE_CLICK);
+    h.viewer.screenSpaceEventHandler.setInputAction(
+      stockDouble,
+      LEFT_DOUBLE_CLICK,
+    );
 
     h.act('toggleDraw');
     assert.equal(
@@ -379,20 +404,34 @@ test('Enter finishes from the canvas and the label field, never from a focused b
     h.tool.addVertex(-97.74, 30.27);
 
     // Enter while the Clear button has keyboard focus means "press Clear".
-    h.documentDouble.emit('keydown', { key: 'Enter', target: h.element('draw-clear') });
+    h.documentDouble.emit('keydown', {
+      key: 'Enter',
+      target: h.element('draw-clear'),
+    });
     await Promise.resolve();
     assert.equal(
       h.annotations.calls.annotate.length,
       0,
       'a focused button keeps its own Enter',
     );
-    assert.equal(h.tool.session.vertices.length, 3, 'and the shape is untouched');
+    assert.equal(
+      h.tool.session.vertices.length,
+      3,
+      'and the shape is untouched',
+    );
 
     // Enter from the page body (the canvas has focus in practice) finishes it.
-    h.documentDouble.emit('keydown', { key: 'Enter', target: h.documentDouble.body });
+    h.documentDouble.emit('keydown', {
+      key: 'Enter',
+      target: h.documentDouble.body,
+    });
     await Promise.resolve();
     await Promise.resolve();
-    assert.equal(h.annotations.calls.annotate.length, 1, 'Enter on the map finishes');
+    assert.equal(
+      h.annotations.calls.annotate.length,
+      1,
+      'Enter on the map finishes',
+    );
     assert.equal(h.annotations.calls.annotate[0].specs[0].type, 'area');
   } finally {
     h.restore();
@@ -421,7 +460,10 @@ test('the live preview hangs at the height the click landed on', async () => {
 
     // …and the finished shape is still flattened, deliberately: the renderer
     // drapes, so a height carried further would be discarded out of sight.
-    h.documentDouble.emit('keydown', { key: 'Enter', target: h.documentDouble.body });
+    h.documentDouble.emit('keydown', {
+      key: 'Enter',
+      target: h.documentDouble.body,
+    });
     await Promise.resolve();
     await Promise.resolve();
     const spec = h.annotations.calls.annotate[0].specs[0];
@@ -477,8 +519,16 @@ test('destroy releases the pointer, the handler, the listeners and the stock act
       stockClick,
       'the viewer got its selecting click back',
     );
-    assert.equal(h.viewer._attached.length, 0, 'the preview data source is detached');
-    assert.equal(h.annotations.listeners.size, 0, 'and it no longer follows the board');
+    assert.equal(
+      h.viewer._attached.length,
+      0,
+      'the preview data source is detached',
+    );
+    assert.equal(
+      h.annotations.listeners.size,
+      0,
+      'and it no longer follows the board',
+    );
 
     // Idempotent: a second destroy is harmless.
     await h.tool.destroy();
@@ -497,7 +547,11 @@ test('Clear wipes the board and the shape in progress', async () => {
 
     h.act('clearDraw');
     assert.equal(h.annotations.calls.clear, 1, 'placed marks are removed');
-    assert.equal(h.tool.session.vertices.length, 0, 'and so is the shape in progress');
+    assert.equal(
+      h.tool.session.vertices.length,
+      0,
+      'and so is the shape in progress',
+    );
   } finally {
     h.restore();
   }
@@ -511,7 +565,13 @@ test('the controls choose the shape and colour the next shape is drawn with; it
     h.act('setDrawColor', 'amber');
     assert.deepEqual(
       { ...h.shown.view, hint: undefined },
-      { active: true, shape: 'line', color: 'amber', hint: undefined, marks: [] },
+      {
+        active: true,
+        shape: 'line',
+        color: 'amber',
+        hint: undefined,
+        marks: [],
+      },
       'the view shows what the controls chose',
     );
     h.act('setDrawColor', 'purple');
@@ -523,7 +583,10 @@ test('the controls choose the shape and colour the next shape is drawn with; it
     assert.equal(h.tool.session.vertices.length, 0);
     h.tool.addVertex(-97.75, 30.26);
     h.tool.addVertex(-97.74, 30.26);
-    h.documentDouble.emit('keydown', { key: 'Enter', target: h.documentDouble.body });
+    h.documentDouble.emit('keydown', {
+      key: 'Enter',
+      target: h.documentDouble.body,
+    });
     await Promise.resolve();
     await Promise.resolve();
     const spec = h.annotations.calls.annotate[0].specs[0];
@@ -548,12 +611,31 @@ test('each drawn shape is a row whose actions reach the board, and fly-to is a n
   try {
     const board = h.annotations;
     board.marks.push(
-      { id: 'a1', type: 'route', manual: true, name: null, label: '950 m', color: 'amber', hidden: false },
-      { id: 'a2', type: 'pin', manual: false, label: 'Voice pin', color: 'primary', hidden: false },
+      {
+        id: 'a1',
+        type: 'route',
+        manual: true,
+        name: null,
+        label: '950 m',
+        color: 'amber',
+        hidden: false,
+      },
+      {
+        id: 'a2',
+        type: 'pin',
+        manual: false,
+        label: 'Voice pin',
+        color: 'primary',
+        hidden: false,
+      },
     );
     board.changed();
     assert.deepEqual(
-      h.shown.view.marks.map(({ id, placeholder, hidden }) => ({ id, placeholder, hidden })),
+      h.shown.view.marks.map(({ id, placeholder, hidden }) => ({
+        id,
+        placeholder,
+        hidden,
+      })),
       [{ id: 'a1', placeholder: 'Line · 950 m', hidden: false }],
       'only hand-drawn marks are listed, an unnamed line by its length',
     );
@@ -568,7 +650,11 @@ test('each drawn shape is a row whose actions reach the board, and fly-to is a n
     ]);
     assert.deepEqual(board.calls.setHidden, [['a1', true]]);
     assert.deepEqual(board.calls.frame, ['a1']);
-    assert.deepEqual(navigations, ['drawing'], 'fly-to goes through the navigation policy');
+    assert.deepEqual(
+      navigations,
+      ['drawing'],
+      'fly-to goes through the navigation policy',
+    );
     assert.deepEqual(board.calls.remove, ['a1']);
     assert.deepEqual(h.shown.view.marks, [], 'the row goes with its mark');
   } finally {
@@ -582,30 +668,49 @@ test('Backspace on the page removes the last vertex', () => {
     h.act('toggleDraw');
     h.tool.addVertex(-97.75, 30.26);
     h.tool.addVertex(-97.74, 30.26);
-    h.documentDouble.emit('keydown', { key: 'Backspace', target: h.documentDouble.body });
+    h.documentDouble.emit('keydown', {
+      key: 'Backspace',
+      target: h.documentDouble.body,
+    });
     assert.equal(h.tool.session.vertices.length, 1);
   } finally {
     h.restore();
   }
 });
 
-test('keys on the shape list are the list\'s, not the drawing\'s', async () => {
+test("keys on the shape list are the list's, not the drawing's", async () => {
   const h = harness();
   try {
     const listButton = new FakeElement('BUTTON');
-    listButton.closest = (selector) => (selector === '#draw-mark-list' ? {} : null);
+    listButton.closest = (selector) =>
+      selector === '#draw-mark-list' ? {} : null;
     const elsewhere = new FakeElement('INPUT', 'location-search');
     h.act('toggleDraw');
     h.tool.addVertex(-97.75, 30.26);
     h.tool.addVertex(-97.74, 30.26);
     h.documentDouble.emit('keydown', { key: 'Escape', target: listButton });
-    assert.equal(h.tool.session.vertices.length, 2, 'Escape in the list keeps the shape');
+    assert.equal(
+      h.tool.session.vertices.length,
+      2,
+      'Escape in the list keeps the shape',
+    );
     assert.equal(h.tool.active, true, 'and keeps Draw on');
     h.documentDouble.emit('keydown', { key: 'Enter', target: elsewhere });
     await Promise.resolve();
-    assert.equal(h.annotations.calls.annotate.length, 0, 'another field keeps its Enter');
-    h.documentDouble.emit('keydown', { key: 'Escape', target: h.documentDouble.body });
-    assert.equal(h.tool.session.vertices.length, 0, 'Escape on the page drops the open shape');
+    assert.equal(
+      h.annotations.calls.annotate.length,
+      0,
+      'another field keeps its Enter',
+    );
+    h.documentDouble.emit('keydown', {
+      key: 'Escape',
+      target: h.documentDouble.body,
+    });
+    assert.equal(
+      h.tool.session.vertices.length,
+      0,
+      'Escape on the page drops the open shape',
+    );
   } finally {
     h.restore();
   }
@@ -632,3 +737,36 @@ test('a page without the Draw controls gets no draw tool', () => {
     else globalThis.document = previousDocument;
   }
 });
+
+test('an engine switch ends an open sketch and keeps the chosen shape and colour', async () => {
+  const h = harness({ session: true });
+  try {
+    const handle = h.tool;
+    assert.equal(globalThis.window.__gevDrawTool, handle);
+    h.act('setDrawShape', 'line');
+    h.act('setDrawColor', 'amber');
+    h.act('toggleDraw');
+    assert.equal(pointerOwner(), 'draw');
+    assert.equal(handle.active, true);
+
+    await handle.detachScene();
+    assert.equal(isPointerFree(), true, 'the sketch gave the pointer back');
+    assert.equal(handle.active, false);
+    assert.equal(handle.attached, false);
+    assert.equal(h.controls.actions, null, 'no viewer answers the controls');
+    assert.equal(globalThis.window.__gevDrawTool, handle);
+
+    handle.attachScene({ viewer: fakeViewer() });
+    assert.equal(handle.attached, true);
+    assert.equal(handle.shape, 'line');
+    assert.equal(handle.color, 'amber');
+    assert.equal(h.shown.view.shape, 'line');
+    h.act('toggleDraw');
+    assert.equal(handle.active, true);
+    await handle.destroy();
+    assert.equal(isPointerFree(), true);
+    assert.equal(globalThis.window.__gevDrawTool, undefined);
+  } finally {
+    h.restore();
+  }
+});

src/app/tools.js

@@ -1,6 +1,6 @@
 import { SceneDirector } from '../scenes/director.js';
 import { createSessionAnnotations } from '../annotations/index.js';
-import { initDrawTool } from '../annotations/drawTool.js';
+import { createSessionDrawTool } from '../annotations/drawTool.js';
 import { createGeoFileImport } from '../ui/geoFileImport.js';
 import { useDisplayStore } from '../ui/stores/display.js';
 import { applicationPinia } from '../ui/vueRuntime.js';
@@ -161,18 +161,20 @@ export function createApplicationTools({
     const token = displayStore.connect(actions);
     return () => displayStore.detach(token);
   };
-  // UTILITIES ▸ Draw: the same whiteboard, drawn by hand. It claims the pointer
-  // while a session is open, so its teardown belongs to the application
-  // lifetime rather than to whoever last pressed the button. A row's fly-to
-  // goes through the shell's navigation policy, as Import's does.
-  const drawTool = initDrawTool({
-    viewer,
-    annotations,
-    navigation: styleManager,
-    publish: (view) => displayStore.publishDraw(view),
-    connect: connectDisplay,
-  });
-  defer(() => drawTool?.destroy());
+  // UTILITIES ▸ Draw: the same whiteboard, drawn by hand. The marks and the
+  // chosen shape belong to the page session; the tool claims this viewer's
+  // pointer while a sketch is open, so an engine switch ends the sketch. A
+  // row's fly-to goes through the shell's navigation policy, as Import's does.
+  const drawTool = sessionTool(layerSession, 'draw', defer, () =>
+    createSessionDrawTool({
+      annotations,
+      navigation: styleManager,
+      publish: (view) => displayStore.publishDraw(view),
+      connect: connectDisplay,
+    }),
+  );
+  drawTool?.attachScene({ viewer, navigation: styleManager });
+  defer(() => drawTool?.detachScene());
   // UTILITIES ▸ Import: the person's own GeoJSON/KML/KMZ/GPX files, each its
   // own data source. They live for the page session: an engine switch takes
   // them off this viewer, and the next Cesium viewer reads them again. The

src/ui/geoFileImport.test.mjs

@@ -328,7 +328,9 @@ test('the application composition wires the import and owns its teardown', () =>
     new URL('../app/tools.js', import.meta.url),
     'utf8',
   );
-  const drawAt = tools.indexOf('const drawTool = initDrawTool({');
+  const drawAt = tools.indexOf(
+    "const drawTool = sessionTool(layerSession, 'draw'",
+  );
   const importAt = tools.indexOf(
     "const geoFileImport = sessionTool(layerSession, 'geoImport', defer, () =>",
   );