Release God's Eye View as open source

src/data/trackingClickGesture.js

@@ -0,0 +1,100 @@
+import * as Cesium from 'cesium';
+
+export const MAX_TRACKING_CLICK_TRAVEL_PX = 6;
+export const MAX_TRACKING_CLICK_DURATION_MS = 400;
+
+/**
+ * Decide whether a completed press stayed spatially click-like. Duration is
+ * deliberately ignored so a stationary long press may still select a contact;
+ * callers apply the full click classifier before destructive deselection.
+ * @param {{travelPx?: number}} gesture - Accumulated pointer path.
+ * @returns {boolean} True when travel stays within the click limit.
+ */
+export function isTrackingSelectionGesture(gesture = {}) {
+  const travelPx = Number.isFinite(gesture.travelPx)
+    ? Math.max(0, gesture.travelPx)
+    : Number.POSITIVE_INFINITY;
+  return travelPx <= MAX_TRACKING_CLICK_TRAVEL_PX;
+}
+
+/**
+ * Decide whether a completed press is a clean click suitable for deselection
+ * or another action that requires both short duration and low travel.
+ * @param {{travelPx?: number, durationMs?: number}} gesture - Accumulated path and press time.
+ * @returns {boolean} True when the gesture stays within both click limits.
+ */
+export function isTrackingClickGesture(gesture = {}) {
+  const durationMs = Number.isFinite(gesture.durationMs)
+    ? Math.max(0, gesture.durationMs)
+    : Number.POSITIVE_INFINITY;
+  return isTrackingSelectionGesture(gesture)
+    && durationMs <= MAX_TRACKING_CLICK_DURATION_MS;
+}
+
+/**
+ * Bind LEFT_DOWN/MOUSE_MOVE/LEFT_UP accounting ahead of a scene click.
+ * Travel is accumulated segment-by-segment, so an orbit nudge that returns to
+ * its starting pixel cannot masquerade as a zero-distance click. Every scene
+ * click reaches `onClick` with its gesture metadata; the caller decides whether
+ * selection (travel-only) or deselection (travel + duration) is allowed.
+ * @param {Cesium.ScreenSpaceEventHandler|Object} handler - Input handler.
+ * @param {(click: Object, gesture: {travelPx: number, durationMs: number}) => void} onClick - Scene-click callback.
+ * @param {{now?: () => number, eventTypes?: Object, onMouseMove?: (event: Object) => void}} [options] - Test/interop seams.
+ * @returns {void}
+ */
+export function bindTrackingClickGesture(handler, onClick, options = {}) {
+  const now = options.now || (() => performance.now());
+  const eventTypes = options.eventTypes || Cesium.ScreenSpaceEventType;
+  let pressActive = false;
+  let pressStartedAt = 0;
+  let previousPosition = null;
+  let travelPx = 0;
+  let completedGesture = null;
+
+  const appendTravel = (position) => {
+    if (!pressActive || !Number.isFinite(position?.x) || !Number.isFinite(position?.y)) return;
+    if (previousPosition) {
+      travelPx += Math.hypot(
+        position.x - previousPosition.x,
+        position.y - previousPosition.y,
+      );
+    }
+    previousPosition = { x: position.x, y: position.y };
+  };
+
+  const finishPress = (position) => {
+    if (!pressActive) return;
+    appendTravel(position);
+    completedGesture = {
+      travelPx,
+      durationMs: Math.max(0, now() - pressStartedAt),
+    };
+    pressActive = false;
+    previousPosition = null;
+  };
+
+  handler.setInputAction((event) => {
+    pressActive = true;
+    pressStartedAt = now();
+    previousPosition = null;
+    travelPx = 0;
+    completedGesture = null;
+    appendTravel(event?.position);
+  }, eventTypes.LEFT_DOWN);
+
+  handler.setInputAction((event) => {
+    appendTravel(event?.endPosition ?? event?.position);
+    options.onMouseMove?.(event);
+  }, eventTypes.MOUSE_MOVE);
+
+  handler.setInputAction((event) => {
+    finishPress(event?.position);
+  }, eventTypes.LEFT_UP);
+
+  handler.setInputAction((click) => {
+    if (pressActive) finishPress(click?.position);
+    const gesture = completedGesture || { travelPx: 0, durationMs: 0 };
+    completedGesture = null;
+    onClick(click, gesture);
+  }, eventTypes.LEFT_CLICK);
+}