Preserve QPowerPoint slide backgrounds

src/io/powerPointOffice.ts

@@ -54,6 +54,7 @@ export async function importPptxFile(file: File): Promise<ImportedPowerPointDeck
       const notesPath = await slideNotesPath(zip, parser, path);
       const notesXml = notesPath ? await readOptionalZipText(zip, notesPath) : await readOptionalZipText(zip, `ppt/notesSlides/notesSlide${index}.xml`);
       const notes = notesXml ? extractTextBlocks(parser.parse(notesXml)).join("\n") : "";
+      const backgroundColor = slideBackgroundColor(parsedSlide);
 
       return {
         id: `pptx-slide-${index}`,
@@ -61,6 +62,7 @@ export async function importPptxFile(file: File): Promise<ImportedPowerPointDeck
         subtitle: slideTextBlocks.slice(1).join("\n"),
         notes,
         theme: "classic" as const,
+        ...(backgroundColor ? { backgroundColor } : {}),
         images
       };
     })
@@ -97,7 +99,7 @@ export async function exportPptxBlob(deck: ExportablePowerPointDeck): Promise<Bl
   for (const sourceSlide of deck.slides) {
     const colors = themeColors[sourceSlide.theme] ?? themeColors.classic;
     const slide = pptx.addSlide();
-    slide.background = { color: colors.background };
+    slide.background = { color: normalizeHexColor(sourceSlide.backgroundColor) || colors.background };
     sourceSlide.images?.forEach((image, index) => {
       const data = normalizedImageData(image.src);
       if (!data || !slide.addImage) {
@@ -335,6 +337,19 @@ function normalizedImageData(src: string) {
   return /^data:image\/(?:png|jpe?g|gif|bmp|svg\+xml);base64,/i.test(value) ? value : "";
 }
 
+function slideBackgroundColor(slideXml: unknown) {
+  const background = firstRecordByKey(slideXml, "bg");
+  const backgroundProperties = childRecord(background, "bgPr");
+  const solidFill = childRecord(backgroundProperties, "solidFill");
+  const srgbColor = childRecord(solidFill, "srgbClr");
+  return normalizeHexColor(stringValue(srgbColor.val ?? srgbColor["@_val"]));
+}
+
+function normalizeHexColor(value?: string) {
+  const raw = value?.trim().replace(/^#/, "").toUpperCase() ?? "";
+  return /^[0-9A-F]{6}$/.test(raw) ? raw : "";
+}
+
 function numberAttribute(record: Record<string, unknown>, name: string) {
   const value = Number.parseFloat(stringValue(record[name] ?? record[`@_${name}`]));
   return Number.isFinite(value) ? value : undefined;