feat(文档导出): 优化大文档流式导出，降低内存占用

assets/webui/ofdgo.js

@@ -1496,26 +1496,41 @@ async function exportFile(whole) {
 		return;
 	}
 	const label = whole ? (format.value === "pdf" ? "PDF" : "ZIP") : format.label;
+	const extension = whole ? label.toLowerCase() : format.extension;
+	const mime = whole && format.value !== "pdf" ? "application/zip" : format.mime;
 	const openSeq = state.openSeq;
-	const fileName = whole ? `${baseFileName()}.${label.toLowerCase()}` : pageFileName(format.extension);
+	const fileName = whole ? `${baseFileName()}.${extension}` : pageFileName(extension);
+	const pageIndex = state.pageIndex;
+	const dpi = exportFormatUsesDPI(format.value) ? currentImageDPI() : 0;
 	state.exporting = true;
 	updateControls();
 	setBusy(true, `正在生成 ${label}`, null, whole ? STATUS.exporting : STATUS.pageExporting);
 	try {
-		const dpi = exportFormatUsesDPI(format.value) ? currentImageDPI() : 0;
+		const file = window.showSaveFilePicker ? await window.showSaveFilePicker({
+			suggestedName: fileName,
+			types: [{ description: label, accept: { [mime]: [`.${extension}`] } }],
+		}) : null;
+		if (openSeq !== state.openSeq) {
+			return;
+		}
 		const result = whole
-			? await callWASM("ofdgoExportDocument", format.value, dpi)
-			: await callWASM("ofdgoExportPage", state.pageIndex, format.value, dpi);
+			? await callWASM("ofdgoExportDocument", format.value, dpi, file)
+			: await callWASM("ofdgoExportPage", pageIndex, format.value, dpi, file);
 		if (openSeq !== state.openSeq) {
 			return;
 		}
 		setProgress(`正在保存 ${result.label}`, 100);
-		const bytes = result.bytes;
-		downloadBytes(bytes, result.mime, fileName);
-		setStatus(`${result.label} 导出完成 ${formatBytes(bytes.length, result.label)}`);
+		if (result.blob) {
+			downloadBytes(result.blob, result.mime, fileName);
+		}
+		setStatus(`${result.label} 导出完成 ${formatBytes(result.size, result.label)}`);
 	} catch (err) {
 		if (openSeq === state.openSeq) {
-			showError(err, false);
+			if (err.name === "AbortError") {
+				setStatus("导出已取消");
+			} else {
+				showError(err, false);
+			}
 		}
 	} finally {
 		state.exporting = false;

assets/webui/ofdgo.wasm.js

@@ -1,14 +1,49 @@
 importScripts("./wasm_exec.js");
 
-self.onmessage = ({ data: { id, name, args } }) => {
+let pending = Promise.resolve();
+self.onmessage = ({ data }) => {
+	pending = pending.then(() => handleMessage(data));
+};
+async function handleMessage({ id, name, args }) {
+	let output;
 	try {
-		const payload = globalThis[name](...args);
+		const chunks = [];
+		let size = 0;
+		const exporting = name === "ofdgoExportPage" || name === "ofdgoExportDocument";
+		if (exporting) {
+			const file = args.pop();
+			if (file) {
+				output = await file.createWritable();
+			}
+			args.push((bytes, done) => {
+				size += bytes.length;
+				if (output) {
+					output.write(bytes).then(() => done(), (err) => done(err.message));
+				} else {
+					chunks.push(new Blob([bytes]));
+					setTimeout(done, 0);
+				}
+			});
+		}
+		const payload = await globalThis[name](...args);
 		const result = typeof payload === "string" ? JSON.parse(payload) : payload;
+		if (exporting && result.ok) {
+			result.data.size = size;
+			if (output) {
+				await output.close();
+			} else {
+				result.data.blob = new Blob(chunks, { type: result.data.mime });
+			}
+		} else if (output) {
+			await output.abort();
+		}
+		output = null;
 		self.postMessage({ id, ...result }, result.data?.bytes ? [result.data.bytes.buffer] : []);
 	} catch (err) {
+		await output?.abort().catch(() => {});
 		self.postMessage({ id, ok: false, error: err.message });
 	}
-};
+}
 
 function exitWASM(err) {
 	self.postMessage({ type: "exit", error: err?.message || "引擎运行中断" });