refactor(pptx): handle missing animations and depths without fallbacks

Author: TheGreatAxios

packages/pptx/src/deck.ts

@@ -318,16 +318,17 @@ const PATH_ARGUMENTS: Record<string, number> = { M: 2, L: 2, C: 6, Z: 0, E: 0 };
 const MotionPath = type("string").narrow((path, ctx) => {
   const tokens = path.trim().split(/[\s,]+/);
   if (tokens[0] !== "M") return ctx.mustBe("a path starting with M");
-  for (let at = 0; at < tokens.length;) {
-    const count = PATH_ARGUMENTS[tokens[at] ?? ""];
+  let at = 0;
+  for (let command = tokens[at]; command !== undefined; command = tokens[at]) {
+    const count = PATH_ARGUMENTS[command];
     if (count === undefined)
       return ctx.mustBe("a path of M, L, C, Z and E commands with numbers");
     const numbers = tokens.slice(at + 1, at + 1 + count);
     if (
       numbers.length < count ||
       numbers.some((n) => !Number.isFinite(Number(n)))
     )
-      return ctx.mustBe(`a path whose ${tokens[at]} has ${count} numbers`);
+      return ctx.mustBe(`a path whose ${command} has ${count} numbers`);
     at += 1 + count;
   }
   return true;
@@ -499,14 +500,16 @@ const NESTING = [
   },
 ] as const;
 
+type Depths = Record<(typeof NESTING)[number]["key"], number>;
+
 /** Lists and groups nested past their limits, found without recursion before the schema's own recursion can overflow. */
 function deepNesting(input: unknown): DeckIssue[] {
   const issues: DeckIssue[] = [];
   const pending = [
     {
       value: isObject(input) ? input.slides : undefined,
       path: ["slides"] as Path,
-      depths: NESTING.map(() => 0),
+      depths: { items: 0, children: 0 } satisfies Depths,
     },
   ];
   for (let next = pending.pop(); next; next = pending.pop()) {
@@ -515,22 +518,18 @@ function deepNesting(input: unknown): DeckIssue[] {
     const entries = Object.entries(value).reverse();
     for (const [key, child] of entries) {
       const childPath = [...path, Array.isArray(value) ? Number(key) : key];
-      const level = NESTING.findIndex(
-        (nesting, index) =>
-          key === nesting.key &&
+      const nesting = NESTING.find(
+        (each) =>
+          key === each.key &&
           Array.isArray(child) &&
-          nesting.opens(value, depths[index] ?? 0),
+          each.opens(value, depths[each.key]),
       );
-      const nesting = NESTING[level];
-      const depth = depths[level] ?? 0;
       if (!nesting) pending.push({ value: child, path: childPath, depths });
-      else if (depth < nesting.limit)
+      else if (depths[nesting.key] < nesting.limit)
         pending.push({
           value: child,
           path: childPath,
-          depths: depths.map((each, index) =>
-            index === level ? each + 1 : each,
-          ),
+          depths: { ...depths, [nesting.key]: depths[nesting.key] + 1 },
         });
       else
         issues.push(
@@ -654,8 +653,9 @@ function freeSlideIssues(slide: Slide, index: number): DeckIssue[] {
         ),
       );
   }
+  if (!slide.animations) return issues;
   let endless = false;
-  for (const [position, animation] of (slide.animations ?? []).entries()) {
+  for (const [position, animation] of slide.animations.entries()) {
     const path = ["slides", index, "animations", position];
     if (!ids.has(animation.target))
       issues.push(

packages/pptx/src/image.ts

@@ -55,7 +55,7 @@ export function isSvg(bytes: Uint8Array) {
   for (let at = 0; at < bytes.length; at += CHUNK) {
     const end = at + CHUNK >= bytes.length;
     text += decoder.decode(bytes.subarray(at, at + CHUNK), { stream: !end });
-    const rest = text.slice(PROLOG.exec(text)?.[0].length ?? 0);
+    const rest = text.replace(PROLOG, "");
     // An unfinished comment, declaration or tag name needs the next chunk to decide.
     if (end || (rest.length > 4 && !/^<[?!]/.test(rest)))
       return /^<svg[\s/>]/.test(rest);

packages/pptx/src/motion.ts

@@ -17,8 +17,11 @@ const TOWARD: Record<Side, string> = {
   bottom: "up",
 };
 
-const speed = (duration: number) =>
-  duration <= 500 ? "fast" : duration <= 750 ? "med" : "slow";
+function speed(duration: number) {
+  if (duration <= 500) return "fast";
+  if (duration <= 750) return "med";
+  return "slow";
+}
 
 /** An exact duration needs PowerPoint 2010 and Morph needs 2019; older viewers take the fallback, with Morph as a fade. */
 export function transitionXml(transition: Transition) {

packages/pptx/src/write.ts

@@ -441,10 +441,11 @@ function freeSlide(slide: Slide & { layout: "free" }, part: SlidePart) {
     part.shapes.push(elementXml(element, part, targets));
   return {
     background: slide.background ? backgroundXml(slide.background) : "",
-    timing: timingXml(slide.animations ?? [], targets),
+    timing: slide.animations ? timingXml(slide.animations, targets) : "",
   };
 }
 
+/** A placed slide takes its background from the master and has no animations. */
 function placedSlide(
   deck: Deck,
   slide: Exclude<Slide, { layout: "free" }>,
@@ -472,6 +473,7 @@ function placedSlide(
     else if (text !== undefined)
       part.shapes.push(placeholderShape(part.nextId(), placeholder, text));
   }
+  return { background: "", timing: "" };
 }
 
 // Keynote drops an unused Picture with Caption layout and warns about removed media on open.
@@ -495,16 +497,18 @@ function slideXml(
     "slideLayout",
     `../slideLayouts/slideLayout${layouts.indexOf(layout) + 1}.xml`,
   );
-  const free = slide.layout === "free" ? freeSlide(slide, part) : undefined;
-  if (slide.layout !== "free") placedSlide(deck, slide, index, part);
+  const { background, timing } =
+    slide.layout === "free"
+      ? freeSlide(slide, part)
+      : placedSlide(deck, slide, index, part);
   if (slide.notes !== undefined)
     part.rels.add("notesSlide", `../notesSlides/notesSlide${index + 1}.xml`);
   const transition = slide.transition ? transitionXml(slide.transition) : "";
   const masterShapes = slide.layout === "free" ? ' showMasterSp="0"' : "";
   return {
     notes: slide.notes,
     rels: part.rels,
-    xml: `${XML_DECLARATION}<p:sld ${NAMESPACES}${masterShapes}><p:cSld>${free?.background ?? ""}<p:spTree>${GROUP_HEADER}${part.shapes.join("")}</p:spTree></p:cSld><p:clrMapOvr><a:masterClrMapping/></p:clrMapOvr>${transition}${free?.timing ?? ""}</p:sld>`,
+    xml: `${XML_DECLARATION}<p:sld ${NAMESPACES}${masterShapes}><p:cSld>${background}<p:spTree>${GROUP_HEADER}${part.shapes.join("")}</p:spTree></p:cSld><p:clrMapOvr><a:masterClrMapping/></p:clrMapOvr>${transition}${timing}</p:sld>`,
   };
 }
 

packages/pptx/test/pptx.test.ts

@@ -305,20 +305,21 @@ test("each effect on a shape is its own build, and wipes travel away from their
   const timed = parts
     .map(({ data }) => new TextDecoder().decode(data))
     .find((xml) => xml.includes("<p:timing>"));
+  if (timed === undefined) throw new Error("no slide has a timing tree");
   const effects = [
-    ...(timed ?? "").matchAll(
+    ...timed.matchAll(
       /grpId="(\d+)" nodeType="\w+"><p:stCondLst>.*?<p:spTgt spid="(\d+)"\/>/g,
     ),
   ].map(([, grpId, spid]) => `${spid}:${grpId}`);
   expect(effects.length).toBeGreaterThan(
     new Set(effects.map((each) => each.split(":")[0])).size,
   );
   expect(new Set(effects).size).toBe(effects.length);
-  for (const [, spid, grpId] of (timed ?? "").matchAll(
+  for (const [, spid, grpId] of timed.matchAll(
     /<p:bldP spid="(\d+)" grpId="(\d+)"/g,
   ))
     expect(effects).toContain(`${spid}:${grpId}`);
-  const wipes = [...(timed ?? "").matchAll(/filter="(wipe\(\w+\))"/g)].map(
+  const wipes = [...timed.matchAll(/filter="(wipe\(\w+\))"/g)].map(
     ([, filter]) => filter,
   );
   expect(wipes).toEqual(["wipe(right)", "wipe(left)"]);