snapshot of https://github.com/excalidraw/excalidraw.git (master, 2026-09-16; blobs > 131072B omitted)

packages/excalidraw/renderOverrides.ts

@@ -0,0 +1,70 @@
+import { clamp } from "@excalidraw/math";
+
+import type {
+  ElementRenderOffsets,
+  ElementRenderOverride,
+  ElementRenderOverrides,
+} from "./types";
+
+/** Validate and copy before publishing, so a rejected snapshot changes nothing. */
+export const copyElementRenderOverrides = (
+  overrides: ElementRenderOverrides | null,
+): ElementRenderOverrides => {
+  const copy = new Map<string, ElementRenderOverride>();
+  for (const [id, value] of overrides ?? []) {
+    const { opacity, offset } = value;
+    if (
+      (opacity !== undefined && !Number.isFinite(opacity)) ||
+      (offset !== undefined &&
+        (offset === null ||
+          !Number.isFinite(offset.x) ||
+          !Number.isFinite(offset.y)))
+    ) {
+      throw new TypeError(`Render overrides for ${id} must be finite numbers`);
+    }
+    if (opacity === undefined && offset === undefined) {
+      continue;
+    }
+    copy.set(id, {
+      ...(opacity !== undefined ? { opacity: clamp(opacity, 0, 100) } : {}),
+      ...(offset ? { offset: { x: offset.x, y: offset.y } } : {}),
+    });
+  }
+  return copy;
+};
+
+/**
+ * Extracts the offsets of a snapshot, returning `previous` when they are the
+ * same. Visibility is memoized on this map's identity, so a snapshot that only
+ * changes opacities (a fade) never re-runs viewport geometry.
+ */
+export const getElementRenderOffsets = (
+  overrides: ElementRenderOverrides,
+  previous: ElementRenderOffsets,
+): ElementRenderOffsets => {
+  // Compare before allocating: fades can carry many unchanged offsets.
+  let offsetCount = 0;
+  let changed = false;
+  for (const [id, { offset }] of overrides) {
+    if (!offset) {
+      continue;
+    }
+    offsetCount++;
+    const before = previous.get(id);
+    if (!before || before.x !== offset.x || before.y !== offset.y) {
+      changed = true;
+      break;
+    }
+  }
+  if (!changed && offsetCount === previous.size) {
+    return previous;
+  }
+
+  const next = new Map<string, NonNullable<ElementRenderOverride["offset"]>>();
+  for (const [id, { offset }] of overrides) {
+    if (offset) {
+      next.set(id, offset);
+    }
+  }
+  return next;
+};