feat(导出文档): 支持取消导出

assets/webui/index.html

@@ -104,6 +104,7 @@
 				<div id="progressPanel" class="progress-panel" role="status" aria-live="polite" hidden>
 					<div class="progress-spinner"></div>
 					<div id="progressLabel" class="progress-label">加载中</div>
+					<button id="cancelExportButton" class="small-button" type="button" title="取消导出" aria-label="取消导出" hidden>取消</button>
 					<div class="progress-track">
 						<div id="progressBar" class="progress-bar" role="progressbar" aria-valuemin="0" aria-valuemax="100" aria-valuenow="0"></div>
 					</div>

assets/webui/ofdgo.css

@@ -803,6 +803,7 @@ button.outline-link:hover {
 .form-row[hidden],
 .page-list[hidden],
 .page-frame[hidden],
+.progress-panel > [hidden],
 .progress-panel[hidden] {
 	display: none;
 }
@@ -825,6 +826,10 @@ button.outline-link:hover {
 	backdrop-filter: blur(8px);
 }
 
+.progress-panel:has(> button:not([hidden])) {
+	grid-template-columns: auto minmax(0, 1fr) auto;
+}
+
 .progress-spinner {
 	width: 18px;
 	height: 18px;

assets/webui/ofdgo.js

@@ -28,6 +28,7 @@ const state = {
 	wasmRecovering: false,
 	wasmRecoveries: 0,
 	exporting: false,
+	exportRequestID: 0,
 	ofdBytes: null,
 	fileName: "ofdgo.ofd",
 	openSeq: 0,
@@ -111,6 +112,7 @@ const el = {
 	emptyState: document.querySelector("#emptyState"),
 	progressPanel: document.querySelector("#progressPanel"),
 	progressLabel: document.querySelector("#progressLabel"),
+	cancelExportButton: document.querySelector("#cancelExportButton"),
 	progressBar: document.querySelector("#progressBar"),
 	pageFrame: document.querySelector("#pageFrame"),
 	viewerPanel: document.querySelector(".viewer-panel"),
@@ -214,6 +216,7 @@ el.exportFormat.addEventListener("change", () => updateDPIControl());
 el.exportPageButton.addEventListener("click", () => exportFile(false));
 el.exportButton.addEventListener("click", openExportPanel);
 el.exportCancel.addEventListener("click", () => el.exportPanel.close());
+el.cancelExportButton.addEventListener("click", cancelExport);
 el.exportPanel.addEventListener("pointerdown", (event) => {
 	state.exportBackdrop = event.target === el.exportPanel;
 });
@@ -673,11 +676,14 @@ async function loadWASM() {
 			} else if (data.type === "export") {
 				if (wasmRequests.get(data.id)?.openSeq === state.openSeq && state.exporting) {
 					if (data.stage === "save") {
+						el.cancelExportButton.disabled = true;
 						setProgress("正在保存", null);
-					} else if (data.completed === data.total) {
-						setProgress("正在封装", null);
-					} else {
-						setProgress(`正在导出 ${data.completed} / ${data.total} 页`, data.completed / data.total * 100);
+					} else if (!el.cancelExportButton.disabled) {
+						if (data.completed === data.total) {
+							setProgress("正在封装", null);
+						} else {
+							setProgress(`正在导出 ${data.completed} / ${data.total} 页`, data.completed / data.total * 100);
+						}
 					}
 				}
 			} else if (data.type === "ready") {
@@ -691,7 +697,11 @@ async function loadWASM() {
 				if (data.ok) {
 					request.resolve(data.data);
 				} else {
-					request.reject(new Error(data.error));
+					const err = new Error(data.error);
+					if (data.canceled) {
+						err.name = "AbortError";
+					}
+					request.reject(err);
 				}
 			}
 		};
@@ -1613,6 +1623,8 @@ async function exportFile(whole, indices = null) {
 		}
 	} finally {
 		state.exporting = false;
+		state.exportRequestID = 0;
+		el.cancelExportButton.hidden = true;
 		if (openSeq === state.openSeq) {
 			setBusy(false);
 			updateControls();
@@ -1620,6 +1632,15 @@ async function exportFile(whole, indices = null) {
 	}
 }
 
+function cancelExport() {
+	if (!state.exportRequestID || el.cancelExportButton.disabled) {
+		return;
+	}
+	el.cancelExportButton.disabled = true;
+	setProgress("正在取消", null);
+	wasmWorker.postMessage({ type: "cancel", id: state.exportRequestID });
+}
+
 function renderPageFlow() {
 	el.svgHost.replaceChildren();
 	el.viewerPanel.classList.remove("single-page-fits-height");
@@ -3312,6 +3333,11 @@ async function callWASM(name, ...args) {
 	return new Promise((resolve, reject) => {
 		const id = ++wasmRequestID;
 		wasmRequests.set(id, { resolve, reject, openSeq: state.openSeq });
+		if (name === "ofdgoExportPage" || name === "ofdgoExportDocument") {
+			state.exportRequestID = id;
+			el.cancelExportButton.hidden = false;
+			el.cancelExportButton.disabled = false;
+		}
 		try {
 			wasmWorker.postMessage({ id, name, args });
 		} catch (err) {

assets/webui/ofdgo.wasm.js

@@ -1,38 +1,61 @@
 importScripts("./wasm_exec.js");
 
 let pending = Promise.resolve();
+const exports = new Map();
 self.onmessage = ({ data }) => {
+	if (data.type === "cancel") {
+		exports.get(data.id)?.abort();
+		return;
+	}
+	if (data.name === "ofdgoExportPage" || data.name === "ofdgoExportDocument") {
+		exports.set(data.id, new AbortController());
+	}
 	pending = pending.then(() => handleMessage(data));
 };
 async function handleMessage({ id, name, args }) {
 	let output;
+	let channel;
+	const signal = exports.get(id)?.signal;
 	try {
+		signal?.throwIfAborted();
 		const chunks = [];
 		let size = 0;
-		const exporting = name === "ofdgoExportPage" || name === "ofdgoExportDocument";
-		if (exporting) {
+		if (signal) {
 			const file = args.pop();
 			if (file) {
 				output = await file.createWritable();
 			}
+			signal.throwIfAborted();
+			channel = new MessageChannel();
+			const finish = (done, err) => {
+				channel.port1.onmessage = () => done(err?.message || "", signal.aborted);
+				channel.port2.postMessage(null);
+			};
 			args.push((bytes, done) => {
+				if (signal.aborted) {
+					finish(done);
+					return;
+				}
 				size += bytes.length;
 				if (output) {
-					output.write(bytes).then(() => done(), (err) => done(err.message));
+					output.write(bytes).then(() => finish(done), (err) => finish(done, err));
 				} else {
 					chunks.push(new Blob([bytes]));
-					setTimeout(done, 0);
+					finish(done);
 				}
 			});
 			if (name === "ofdgoExportDocument") {
-				args.push((completed, total) => {
+				args.push((completed, total, done) => {
 					self.postMessage({ id, type: "export", stage: "pages", completed, total });
+					finish(done);
 				});
 			}
 		}
 		const payload = await globalThis[name](...args);
+		signal?.throwIfAborted();
 		const result = typeof payload === "string" ? JSON.parse(payload) : payload;
-		if (exporting && result.ok) {
+		if (signal && result.ok) {
+			exports.delete(id);
 			result.data.size = size;
 			self.postMessage({ id, type: "export", stage: "save" });
 			if (output) {
@@ -47,7 +70,16 @@ async function handleMessage({ id, name, args }) {
 		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 });
+		const result = { id, ok: false, error: err.message };
+		if (signal?.aborted) {
+			result.error = "导出已取消";
+			result.canceled = true;
+		}
+		self.postMessage(result);
+	} finally {
+		channel?.port1.close();
+		channel?.port2.close();
+		exports.delete(id);
 	}
 }
 

internal/webui/wasm.go

@@ -18,6 +18,7 @@ package webui
 
 import (
 	"bufio"
+	"context"
 	"encoding/json"
 	"fmt"
 	"syscall/js"
@@ -34,21 +35,10 @@ type exportWriter struct {
 // 入参: data 导出数据
 // 返回: int 写入长度, error 错误信息
 func (w exportWriter) Write(data []byte) (int, error) {
-	done := make(chan error)
-	callback := js.FuncOf(func(this js.Value, args []js.Value) any {
-		var err error
-		if len(args) > 0 {
-			err = fmt.Errorf("%s", args[0].String())
-		}
-		done <- err
-		return nil
-	})
-	defer callback.Release()
 	size := len(data)
 	for len(data) > 0 {
 		n := min(len(data), 1<<20)
-		w.write.Invoke(bytesToJS(data[:n]), callback)
-		if err := <-done; err != nil {
+		if err := awaitExport(w.write, bytesToJS(data[:n])); err != nil {
 			return size - len(data), err
 		}
 		data = data[n:]
@@ -56,6 +46,26 @@ func (w exportWriter) Write(data []byte) (int, error) {
 	return size, nil
 }
 
+// awaitExport 等待浏览器处理导出检查点
+// 入参: fn 浏览器回调, args 回调参数
+// 返回: error 写入错误或取消原因
+func awaitExport(fn js.Value, args ...any) error {
+	done := make(chan error)
+	callback := js.FuncOf(func(this js.Value, args []js.Value) any {
+		var err error
+		if args[1].Bool() {
+			err = context.Canceled
+		} else if message := args[0].String(); message != "" {
+			err = fmt.Errorf("%s", message)
+		}
+		done <- err
+		return nil
+	})
+	defer callback.Release()
+	fn.Invoke(append(args, callback)...)
+	return <-done
+}
+
 // currentSession 当前WebUI文档会话
 var currentSession *Session
 
@@ -336,8 +346,8 @@ func exportDocument(args []js.Value) (any, error) {
 		return nil, fmt.Errorf("ofd document is not opened")
 	}
 	renderer := currentSession.Renderer
-	renderer.OnExportProgress = func(completed, total int) {
-		args[4].Invoke(completed, total)
+	renderer.OnExportProgress = func(completed, total int) error {
+		return awaitExport(args[4], completed, total)
 	}
 	defer func() { renderer.OnExportProgress = nil }()
 	var indices []int

ofdgo_renderer.go

@@ -24,13 +24,13 @@ import (
 // Renderer 渲染器实现
 // 通过NewRenderer创建，实例及共享的Reader需串行使用
 // OnPageText可选，接收页面绘制时同步提取的文字，不包含图案和签名外观
-// OnExportProgress可选，同步回报文档导出的已处理页数及总页数，不代表封装或写入成功
+// OnExportProgress可选，同步回报文档导出的已处理页数及总页数，返回错误则停止，页数完成不代表写入成功
 type Renderer struct {
 	Reader                *Reader
 	DPI                   float64
 	RenderAnnotations     bool
 	OnPageText            func(*PageContent, *PageText)
-	OnExportProgress      func(completed, total int)
+	OnExportProgress      func(completed, total int) error
 	DrawParams            map[string]*DrawParam
 	CompositeGraphicUnits map[string]*CompositeGraphicUnit
 	fontFamily            *canvas.FontFamily

ofdgo_renderer_output.go

@@ -90,8 +90,8 @@ func (r *Renderer) RenderToZIP(writer io.Writer, format string, indices ...int)
 		method = zip.Store
 	}
 	width := len(strconv.Itoa(count))
-	if r.OnExportProgress != nil {
-		r.OnExportProgress(0, len(indices))
+	if err := r.exportProgress(0, len(indices)); err != nil {
+		return err
 	}
 	for i, index := range indices {
 		page, err := r.Reader.PageContentByIndex(index)
@@ -108,13 +108,23 @@ func (r *Renderer) RenderToZIP(writer io.Writer, format string, indices ...int)
 		if err := render(page, entry); err != nil {
 			return fmt.Errorf("failed to export page %d: %w", index+1, err)
 		}
-		if r.OnExportProgress != nil {
-			r.OnExportProgress(i+1, len(indices))
+		if err := r.exportProgress(i+1, len(indices)); err != nil {
+			return err
 		}
 	}
 	return archive.Close()
 }
 
+// exportProgress 回报导出进度并传递调用方的停止原因
+// 入参: completed 已处理页数, total 总页数
+// 返回: error 停止原因
+func (r *Renderer) exportProgress(completed, total int) error {
+	if r.OnExportProgress != nil {
+		return r.OnExportProgress(completed, total)
+	}
+	return nil
+}
+
 // rasterRenderer 保留页面物理尺寸的光栅渲染器
 type rasterRenderer struct {
 	*rasterizer.Rasterizer
@@ -288,8 +298,8 @@ func (r *Renderer) RenderToMultiPagePDF(writer io.Writer, indices ...int) error
 	if err != nil {
 		return err
 	}
-	if r.OnExportProgress != nil {
-		r.OnExportProgress(0, len(indices))
+	if err := r.exportProgress(0, len(indices)); err != nil {
+		return err
 	}
 	pages := make([]pdfPage, len(indices))
 	for i, index := range indices {
@@ -313,8 +323,8 @@ func (r *Renderer) RenderPagesToPDF(contents []*PageContent, writer io.Writer) e
 	if len(contents) == 0 {
 		return fmt.Errorf("no pages found")
 	}
-	if r.OnExportProgress != nil {
-		r.OnExportProgress(0, len(contents))
+	if err := r.exportProgress(0, len(contents)); err != nil {
+		return err
 	}
 	pages := make([]pdfPage, len(contents))
 	for i, page := range contents {
@@ -330,7 +340,7 @@ func (r *Renderer) RenderPagesToPDF(contents []*PageContent, writer io.Writer) e
 // renderPDFPages 渲染页面并复用调用方的字节缓冲
 // 入参: pages 页面列表, writer 输出流, progress 页面处理进度
 // 返回: error 错误信息
-func (r *Renderer) renderPDFPages(pages []pdfPage, writer io.Writer, progress func(int, int)) error {
+func (r *Renderer) renderPDFPages(pages []pdfPage, writer io.Writer, progress func(int, int) error) error {
 	navigation := newPDFNavigation(r, r.Reader.doc, pages)
 	buf, direct := writer.(*bytes.Buffer)
 	if !direct {
@@ -354,7 +364,10 @@ func (r *Renderer) renderPDFPages(pages []pdfPage, writer io.Writer, progress fu
 			return fmt.Errorf("failed to render page %d: %w", i+1, err)
 		}
 		if progress != nil {
-			progress(i+1, len(pages))
+			if err := progress(i+1, len(pages)); err != nil {
+				buf.Truncate(start)
+				return err
+			}
 		}
 	}
 	if err := p.Close(); err != nil {