feat(原生桌面): 优化原生页面与资源加载

assets/webui/ofdgo.js

@@ -133,12 +133,14 @@ const state = {
 	pageCache: new Map(),
 	mediaPlayers: new Map(),
 	svgFonts: new Map(),
+	svgFontLoads: new Map(),
 	svgImages: new Map(),
 	selectedPages: new Set(),
 	documentSelection: null,
 	pageInFlight: new Map(),
 	pageRenderQueue: [],
 	pageRenderRunning: false,
+	pageRenderWorkers: 0,
 	pageObserver: null,
 	visiblePages: new Set(),
 	scrollFrame: 0,
@@ -8969,6 +8971,11 @@ function resetPageFlow(keepCache = false) {
 
 function resetPageLoading() {
 	releaseMediaPlayers();
+	if (nativeHost) {
+		for (const [id, request] of wasmRequests) {
+			if (request.name === "ofdgoRenderPage") wasmWorker?.postMessage({ type: "cancel", id });
+		}
+	}
 	for (const task of state.pageInFlight.values()) {
 		task.resolve(null);
 	}
@@ -9104,6 +9111,9 @@ function loadPageData(index, options = {}) {
 
 function schedulePageRender() {
 	if (state.pageRenderRunning) {
+		if (state.pageRenderWorkers) {
+			while (state.pageRenderQueue.length && state.pageRenderWorkers < (nativeHost?.parallelism || 1)) processPageRenderTasks();
+		}
 		return;
 	}
 	state.pageRenderRunning = true;
@@ -9111,8 +9121,13 @@ function schedulePageRender() {
 }
 
 async function processPageRenderQueue() {
-	try {
 	await nextFrame();
+	await Promise.all(Array.from({ length: nativeHost?.parallelism || 1 }, () => processPageRenderTasks()));
+}
+
+async function processPageRenderTasks() {
+	state.pageRenderWorkers++;
+	try {
 		while (state.pageRenderQueue.length) {
 			let next = 0;
 			for (let index = 1; index < state.pageRenderQueue.length; index++) {
@@ -9128,7 +9143,9 @@ async function processPageRenderQueue() {
 					task.resolve(state.pageCache.get(task.index));
 					continue;
 				}
-				const page = await callWASM("ofdgoRenderPage", task.index, state.renderBackend, state.renderDPI, displayMode() === "raster");
+				const args = [task.index, state.renderBackend, state.renderDPI, displayMode() === "raster"];
+				if (nativeHost) args.push([...state.svgFonts.keys()]);
+				const page = await callWASM("ofdgoRenderPage", ...args);
 				if (state.pageInFlight.get(task.key) !== task) {
 					task.resolve(null);
 					continue;
@@ -9139,6 +9156,7 @@ async function processPageRenderQueue() {
 					if (scope === state.composite && task.openSeq === state.openSeq) scope.objects = objects;
 				}
 				await loadSVGFonts(page.fonts, task.openSeq);
+				for (const font of page.fonts) delete font.data;
 				if (task.openSeq === state.openSeq && state.pageInFlight.get(task.key) === task) {
 					for (const image of page.images) {
 						if (!state.svgImages.has(image.name)) {
@@ -9172,8 +9190,11 @@ async function processPageRenderQueue() {
 			}
 		}
 	} finally {
+		if (--state.pageRenderWorkers === 0) {
 			state.pageRenderRunning = false;
 			if (!state.pageInFlight.size) releasePageResources();
+			if (state.pageRenderQueue.length) schedulePageRender();
+		}
 	}
 }
 
@@ -9196,8 +9217,9 @@ function trimPageCache() {
 	for (const image of state.svgImages.values()) {
 		bytes += image.size;
 	}
+	const budget = nativeHost?.cacheBytes || PAGE_CACHE_BYTES;
 	for (const [index, page] of state.pageCache) {
-		if (state.pageCache.size <= PAGE_CACHE_LIMIT && bytes <= PAGE_CACHE_BYTES) {
+		if (state.pageCache.size <= PAGE_CACHE_LIMIT * Math.max(1, budget / PAGE_CACHE_BYTES) && bytes <= budget) {
 			break;
 		}
 		if (protectedPages.has(index)) {
@@ -9227,7 +9249,19 @@ async function loadSVGFonts(fonts, openSeq) {
 		if (state.svgFonts.has(font.name)) {
 			continue;
 		}
-		const data = await callWASM("ofdgoSVGFontData", font.name);
+		const key = `${openSeq}:${font.name}`;
+		let loading = state.svgFontLoads.get(key);
+		if (!loading) {
+			loading = loadSVGFont(font, openSeq);
+			state.svgFontLoads.set(key, loading);
+		}
+		try { await loading; }
+		finally { if (state.svgFontLoads.get(key) === loading) state.svgFontLoads.delete(key); }
+	}
+}
+
+async function loadSVGFont(font, openSeq) {
+	const data = font.data ? { bytes: font.data } : await callWASM("ofdgoSVGFontData", font.name);
 	if (openSeq !== state.openSeq) {
 		return;
 	}
@@ -9238,7 +9272,6 @@ async function loadSVGFonts(fonts, openSeq) {
 	}
 	document.fonts.add(face);
 	state.svgFonts.set(font.name, face);
-	}
 }
 
 function comparePageRenderTask(a, b) {
@@ -9853,7 +9886,9 @@ function markFlowPageError(index, err) {
 
 function queueNearbyPages(index, openSeq = state.openSeq) {
 	const start = pageGroupStart(index);
-	for (let i = Math.max(0, start - 1); i <= Math.min((state.doc?.pageCount || 1) - 1, start + state.pageLayout + 1); i += 1) {
+	const before = nativeHost ? state.pageLayout : 1;
+	const after = nativeHost ? Math.max(1, Math.min(nativeHost.parallelism, state.pageLayout * 2)) : 1;
+	for (let i = Math.max(0, start - before); i <= Math.min((state.doc?.pageCount || 1) - 1, start + state.pageLayout + after); i += 1) {
 		renderFlowPage(i, { openSeq, priority: 2 });
 	}
 }
@@ -12497,7 +12532,7 @@ async function callWASM(name, ...args) {
 			el.cancelExportButton.disabled = false;
 		}
 		if (name === "ofdgoResources" && resourceElements.Panel.open) resourceManager.requestID = id;
-		wasmRequests.set(id, { resolve, reject, openSeq: state.openSeq });
+		wasmRequests.set(id, { name, resolve, reject, openSeq: state.openSeq });
 		if (name === "ofdgoExportMedia") wasmRequests.get(id).mediaID = args[0];
 		if (name === "ofdgoConvertPDF") {
 			const request = wasmRequests.get(id);

assets/webui/ofdgo_host.js

@@ -87,6 +87,10 @@ class NativeHandle {
 class NativeHost {
 	constructor(bridge) {
 		this.bridge = bridge;
+		this.parallelism = 1;
+		this.cacheBytes = 32 * 1024 * 1024;
+		this.reading = 0;
+		this.readQueue = [];
 		this.resources = typeof FinalizationRegistry === "function" ? new FinalizationRegistry(file => {
 			this.call("release", {file}).catch(() => {});
 		}) : null;
@@ -96,25 +100,40 @@ class NativeHost {
 		return this.bridge.call(`ofdgo.host.${name}`, value, {signal});
 	}
 
-	async decode(value, name = "", key = "", signal) {
-		if (value?.nativeFile) {
-			const file = new NativeFile(value);
-			if (key === "file" || name === "ofdgoConvertPDF" && key === "bytes") return file;
+	async readResource(file, signal) {
+		if (this.reading >= this.parallelism) await new Promise(resolve => this.readQueue.push(resolve));
+		else this.reading++;
 		try {
-				const bytes = await file.arrayBuffer(signal);
-				return key === "blob" ? new Blob([bytes], {type:value.type}) : new Uint8Array(bytes);
+			signal?.throwIfAborted();
+			return await file.arrayBuffer(signal);
 		} finally {
-				await this.call("release", {file:value.nativeFile});
+			try { await this.call("release", {file:file.nativeFile}); }
+			finally {
+				const next = this.readQueue.shift();
+				if (next) next();
+				else this.reading--;
 			}
 		}
-		if (Array.isArray(value)) {
-			for (let i = 0; i < value.length; i++) value[i] = await this.decode(value[i], name, "", signal);
-			return value;
 	}
-		if (value && typeof value === "object") {
-			for (const [field, item] of Object.entries(value)) value[field] = await this.decode(item, name, field, signal);
-			return value;
+
+	async decode(value, name = "", key = "", signal) {
+		const reads = [];
+		const visit = (item, field, replace) => {
+			if (!item || typeof item !== "object" || item instanceof Blob || item instanceof ArrayBuffer || ArrayBuffer.isView(item)) return;
+			if (item.nativeFile) {
+				const file = new NativeFile(item);
+				if (field === "file" || name === "ofdgoConvertPDF" && field === "bytes") replace(file);
+				else reads.push(this.readResource(file, signal).then(bytes => replace(field === "blob" ? new Blob([bytes], {type:item.type}) : new Uint8Array(bytes))));
+				return;
 			}
+			for (const [child, content] of Object.entries(item)) {
+				if (content && typeof content === "object") visit(content, Array.isArray(item) ? "" : child, result => item[child] = result);
+			}
+		};
+		visit(value, key, result => value = result);
+		const results = await Promise.allSettled(reads);
+		const failed = results.find(result => result.status === "rejected");
+		if (failed) throw failed.reason;
 		return value;
 	}
 
@@ -134,14 +153,17 @@ class NativeHost {
 		let closed = false;
 		let unsubscribe;
 		let pending = Promise.resolve();
+		const readers = new Set();
 		const requests = new Map();
 		const completions = new Map();
 		const emit = data => {
 			if (data.type === "result") { completions.get(data.id)?.(data.result); return; }
 			if (!closed) worker.onmessage?.({data});
 		};
-		const ready = host.call("engine.open", {}).then(({engine}) => {
+		const ready = host.call("engine.open", {}).then(({engine, parallelism, cacheBytes}) => {
 			if (closed) return engine;
+			host.parallelism = Math.max(1, parallelism || 1);
+			host.cacheBytes = cacheBytes || host.cacheBytes;
 			unsubscribe = host.bridge.on(`ofdgo.engine.${engine}`, emit);
 			emit({type:"ready"});
 			return engine;
@@ -158,7 +180,9 @@ class NativeHost {
 				if (data.type === "font") return;
 				const controller = new AbortController();
 				requests.set(data.id, controller);
-				const operation = pending.then(async () => {
+				const parallel = data.name === "ofdgoRenderPage";
+				const barrier = parallel ? pending : Promise.all([pending, ...readers]);
+				const operation = barrier.then(async () => {
 					const engine = await ready;
 					if (closed) return;
 					controller.signal.throwIfAborted();
@@ -189,7 +213,10 @@ class NativeHost {
 					if (closed) { await host.release(result); return; }
 					emit({id:data.id, ...decoded});
 				}).catch(error => emit({id:data.id, ok:false, error:error.message, code:error.code, canceled:error.name === "AbortError"})).finally(() => requests.delete(data.id));
-				if (data.name !== "ofdgoSaveSnapshot") pending = operation;
+				if (parallel) {
+					readers.add(operation);
+					operation.finally(() => readers.delete(operation));
+				} else if (data.name !== "ofdgoSaveSnapshot") pending = operation;
 			},
 			terminate() {
 				if (closed) return;

internal/webui/webui.go

@@ -1012,7 +1012,11 @@ func (s *Session) pageContent(index int) (*ofdgo.PageContent, error) {
 		return page, nil
 	}
 	clear(s.pageCache)
-	page, err := s.Reader.PageContentByIndex(index)
+	ctx := s.Renderer.OutputContext
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	page, err := s.Reader.PageContentByIndexContext(ctx, index)
 	if err != nil {
 		return nil, err
 	}

internal/webui/webui_native.go

@@ -24,8 +24,10 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"maps"
 	"math"
 	"reflect"
+	"runtime"
 	"strings"
 	"sync"
 
@@ -63,12 +65,15 @@ type NativeOutputTarget struct {
 	Base, Name  string
 }
 
-// NativeEngine 保存独立会话，不同实例可并行，同一实例的回调不可重入Call或Close
+// NativeEngine 保存独立会话，页面渲染可并行，修改等待已开始的只读任务完成
+// 同一实例的回调不可重入Call或Close
 // hooks应在首次Call前配置，Resolve返回的资源需保持有效直到相应会话关闭
 type NativeEngine struct {
 	businessEngine
 	// ConversionPool 协调不同会话的批量转换资源
 	ConversionPool *ofdgo.ConversionPool
+	// RenderParallelism 限制同时渲染的页面数，零值使用可用处理器数
+	RenderParallelism int
 	// Resolve 按授权标识提供资源读取源
 	Resolve NativeResolver
 	// LoadFont 按名称读取系统字体数据
@@ -84,6 +89,11 @@ type NativeEngine struct {
 	once          sync.Once
 	saves         sync.WaitGroup
 	closed        bool
+	renderMu      sync.Mutex
+	renderCount   int
+	renderDone    chan struct{}
+	renderSlots   chan struct{}
+	renderIdle    []*Session
 }
 
 // nativeReader 在会话当前操作上下文中分块读取，不捕获已结束请求的上下文
@@ -139,12 +149,21 @@ func NewNativeEngine(resolve NativeResolver) *NativeEngine { return &NativeEngin
 func (e *NativeEngine) Call(ctx context.Context, name string, args []any, emit func(any)) (result map[string]any) {
 	e.once.Do(func() {
 		e.gate = make(chan struct{}, 1)
+		e.renderSlots = make(chan struct{}, e.renderParallelism())
 		e.resolveInput = e.input
 		e.conversionPool = e.ConversionPool
 	})
 	if ctx == nil {
 		ctx = context.Background()
 	}
+	if name == "ofdgoRenderPage" {
+		select {
+		case e.renderSlots <- struct{}{}:
+			defer func() { <-e.renderSlots }()
+		case <-ctx.Done():
+			return nativeFailure(ctx.Err())
+		}
+	}
 	select {
 	case e.gate <- struct{}{}:
 	case <-ctx.Done():
@@ -162,6 +181,84 @@ func (e *NativeEngine) Call(ctx context.Context, name string, args []any, emit f
 	if e.closed {
 		return nativeFailure(fmt.Errorf("native engine is closed"))
 	}
+	if name == "ofdgoRenderPage" && e.currentSession != nil {
+		defer func() {
+			if failure := recover(); failure != nil {
+				result = nativeFailure(fmt.Errorf("%v", failure))
+			}
+		}()
+		worker, err := e.renderSession(ctx)
+		if err != nil {
+			return nativeFailure(err)
+		}
+		operation := &businessEngine{currentSession: worker, currentEditor: e.currentEditor, ctx: ctx}
+		values := make([]platformValue, len(args))
+		for i, arg := range args {
+			values[i] = platformValueOf(arg)
+		}
+		if len(values) > 0 && operation.currentEditor != nil {
+			pageErr := e.prepareRender(operation, values[0].Int())
+			if pageErr != nil {
+				return nativeFailure(pageErr)
+			}
+		}
+		operation.currentEditor = nil
+		e.renderMu.Lock()
+		if e.renderCount == 0 {
+			e.renderDone = make(chan struct{})
+		}
+		e.renderCount++
+		e.renderMu.Unlock()
+		<-e.gate
+		locked = false
+		defer func() {
+			worker.Renderer.OutputContext = context.Background()
+			e.renderMu.Lock()
+			e.currentSession.svgFonts = maps.Clone(worker.svgFonts)
+			e.renderIdle = append(e.renderIdle, worker)
+			e.renderCount--
+			if e.renderCount == 0 {
+				close(e.renderDone)
+			}
+			e.renderMu.Unlock()
+		}()
+		data, err := operation.safeCall(operation.renderPage, values)
+		if err != nil {
+			return nativeFailure(err)
+		}
+		result = nativePlain(data).(map[string]any)
+		if result["ok"] != true {
+			return result
+		}
+		page := result["data"].(map[string]any)
+		known := make(map[string]bool)
+		if len(args) > 4 {
+			for i := 0; i < values[4].Length(); i++ {
+				known[values[4].Index(i).String()] = true
+			}
+		}
+		for _, value := range page["fonts"].([]any) {
+			font := value.(map[string]any)
+			if name := font["name"].(string); !known[name] {
+				font["data"] = worker.svgFonts[name]
+			}
+		}
+		if e.currentEditor != nil {
+			objects, textErr := e.renderObjects(operation, values[0].Int())
+			if textErr != nil {
+				return nativeFailure(textErr)
+			}
+			page["objects"] = nativePlain(objects)
+		}
+		if err := ctx.Err(); err != nil {
+			return nativeFailure(err)
+		}
+		return result
+	}
+	if err := e.waitRenders(ctx); err != nil {
+		return nativeFailure(err)
+	}
+	e.renderIdle = nil
 	if name == "ofdgoSaveSnapshot" {
 		snapshot := e.saveSnapshot
 		e.saveSnapshot = nil
@@ -236,10 +333,16 @@ func (e *NativeEngine) Call(ctx context.Context, name string, args []any, emit f
 
 // Close 释放会话，不关闭宿主持有的ReaderAt资源
 func (e *NativeEngine) Close() error {
-	e.once.Do(func() { e.gate = make(chan struct{}, 1); e.resolveInput = e.input })
+	e.once.Do(func() {
+		e.gate = make(chan struct{}, 1)
+		e.renderSlots = make(chan struct{}, e.renderParallelism())
+		e.resolveInput = e.input
+	})
 	e.gate <- struct{}{}
 	defer func() { <-e.gate }()
 	e.closed = true
+	_ = e.waitRenders(context.Background())
+	e.renderIdle = nil
 	e.saveSnapshot = nil
 	e.saves.Wait()
 	var err error
@@ -253,6 +356,85 @@ func (e *NativeEngine) Close() error {
 	return err
 }
 
+// waitRenders 等待已开始的页面任务，取消等待不修改当前会话
+// 入参: ctx 等待上下文
+// 返回: error 取消错误
+func (e *NativeEngine) waitRenders(ctx context.Context) error {
+	e.renderMu.Lock()
+	done, count := e.renderDone, e.renderCount
+	e.renderMu.Unlock()
+	if count == 0 {
+		return ctx.Err()
+	}
+	select {
+	case <-done:
+		return ctx.Err()
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+// renderParallelism 返回首次调用时采用的页面并行数
+// 返回: int 同时运行的页面任务数
+func (e *NativeEngine) renderParallelism() int {
+	if e.RenderParallelism > 0 {
+		return e.RenderParallelism
+	}
+	return runtime.GOMAXPROCS(0)
+}
+
+// renderSession 复用独立只读会话，调用时已持有引擎门控
+// 入参: ctx 渲染上下文
+// 返回: *Session 渲染会话, error 准备错误
+func (e *NativeEngine) renderSession(ctx context.Context) (*Session, error) {
+	e.renderMu.Lock()
+	defer e.renderMu.Unlock()
+	if count := len(e.renderIdle); count > 0 {
+		worker := e.renderIdle[count-1]
+		e.renderIdle = e.renderIdle[:count-1]
+		worker.Renderer.OutputContext = ctx
+		return worker, nil
+	}
+	source := e.currentSession
+	renderer, err := source.Renderer.Fork(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return &Session{Reader: renderer.Reader, Renderer: renderer, doc: source.doc, fontFS: source.fontFS,
+		pageCache: make(map[int]*ofdgo.PageContent), boxCache: append([]pageBoxInfo(nil), source.boxCache...),
+		textCache: make(map[int]*ofdgo.PageText), svgFonts: make(map[string][]byte), editing: source.editing}, nil
+}
+
+// prepareRender 同步当前编辑页面的图元标识，避免并行访问编辑器缓存
+// 入参: operation 只读任务, index 页面索引
+// 返回: error 页面或取消错误
+func (e *NativeEngine) prepareRender(operation *businessEngine, index int) error {
+	e.renderMu.Lock()
+	defer e.renderMu.Unlock()
+	page, err := operation.currentEditor.Page(index)
+	if err != nil {
+		return err
+	}
+	return operation.syncEditorPageIDs(index, page)
+}
+
+// renderObjects 读取编辑图元信息，渲染状态由当前任务独立持有
+// 入参: operation 只读任务, index 页面索引
+// 返回: []any 图元信息, error 提取错误
+func (e *NativeEngine) renderObjects(operation *businessEngine, index int) ([]any, error) {
+	e.renderMu.Lock()
+	defer e.renderMu.Unlock()
+	operation.currentEditor = e.currentEditor
+	if !reflect.DeepEqual(e.currentEditor.Backends(), operation.currentSession.Renderer.Backends()) {
+		e.currentEditor.SetRenderBackends(operation.currentSession.Renderer.Backends())
+	}
+	text, err := operation.currentSession.PageText(index)
+	if err != nil {
+		return nil, err
+	}
+	return operation.editorObjects(index, text)
+}
+
 // input 读取授权源并以宿主报告的大小为准
 func (e *NativeEngine) input(ctx context.Context, value any) (io.ReaderAt, int64, error) {
 	if err := ctx.Err(); err != nil {

internal/webview/webview.go

@@ -28,6 +28,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"runtime"
 	"sort"
 	"strconv"
 	"strings"
@@ -267,6 +268,13 @@ func (h *Host) call(ctx context.Context, name string, value any) (any, error) {
 	switch name {
 	case "engine.open":
 		engine := webui.NewNativeEngine(h.files.resolve)
+		parallelism, cacheBytes := runtime.GOMAXPROCS(0), int64(128<<20)
+		if memory := conversionMemory; memory != nil {
+			available := memory()
+			parallelism = max(1, min(parallelism, int(available/(256<<20))))
+			cacheBytes = max(32<<20, min(256<<20, available/16))
+		}
+		engine.RenderParallelism = parallelism
 		engine.ConversionPool = h.conversionPool
 		engine.OpenWriter = h.openWriter
 		engine.ReserveOutput = h.reserveOutput
@@ -280,7 +288,7 @@ func (h *Host) call(ctx context.Context, name string, value any) (any, error) {
 		}
 		h.engineStops[id] = context.AfterFunc(guigo.PageContext(ctx), func() { _ = h.closeEngine(id) })
 		h.mu.Unlock()
-		return guigo.Result{Value: map[string]any{"engine": id}, Discard: func() { _ = h.closeEngine(id) }}, nil
+		return guigo.Result{Value: map[string]any{"engine": id, "parallelism": parallelism, "cacheBytes": cacheBytes}, Discard: func() { _ = h.closeEngine(id) }}, nil
 	case "batch":
 		return map[string]any{"parallelism": h.conversionPool.Parallelism()}, nil
 	case "engine.close":

ofdgo_reader.go

@@ -95,6 +95,33 @@ func (r *Reader) Close() error {
 	return nil
 }
 
+// Fork 创建保留当前文档及历史版本的独立只读视图，不复制包内文件数据
+// 创建过程需与原实例串行，返回后可并行读取，公开结构及底层输入不得并发修改
+// 返回值不持有输入所有权，全部视图使用结束前不得关闭或替换原输入
+// 入参: ctx 取消上下文
+// 返回: *Reader 独立阅读器, error 准备或取消错误
+func (r *Reader) Fork(ctx context.Context) (*Reader, error) {
+	if _, err := r.DocContext(ctx); err != nil {
+		return nil, err
+	}
+	next := *r
+	next.Closer = nil
+	next.resourcesRead = maps.Clone(r.resourcesRead)
+	next.resourceFiles = maps.Clone(r.resourceFiles)
+	next.ResMap = maps.Clone(r.ResMap)
+	next.mediaCache = maps.Clone(r.mediaCache)
+	next.fontCache = maps.Clone(r.fontCache)
+	next.fontFaces = maps.Clone(r.fontFaces)
+	next.colorSpaceCache = maps.Clone(r.colorSpaceCache)
+	next.drawParamCache = maps.Clone(r.drawParamCache)
+	next.compositeGraphicUnitCache = maps.Clone(r.compositeGraphicUnitCache)
+	next.pageHeaderCache = maps.Clone(r.pageHeaderCache)
+	next.Annots = maps.Clone(r.Annots)
+	next.Stamps = maps.Clone(r.Stamps)
+	next.annotationFiles = maps.Clone(r.annotationFiles)
+	return &next, ctx.Err()
+}
+
 // DocumentCount 获取包内文档数量
 // 返回: int 文档数量
 func (r *Reader) DocumentCount() int {

ofdgo_render_cache.go

@@ -18,12 +18,14 @@ import (
 	"container/list"
 	"image"
 	"reflect"
+	"sync"
 
 	baseimage "github.com/xiaoqidun/ofdgo/internal/base/image"
 )
 
 // renderCache 按估算字节数限制派生渲染数据，淘汰不修改源资源
 type renderCache[K comparable, V any] struct {
+	mu          sync.Mutex
 	limit, used int
 	entries     map[K]*list.Element
 	order       list.List
@@ -40,6 +42,8 @@ type renderCacheEntry[K comparable, V any] struct {
 // 入参: key 缓存键
 // 返回: V 缓存值, bool 是否命中
 func (c *renderCache[K, V]) get(key K) (V, bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
 	if item := c.entries[key]; item != nil {
 		c.order.MoveToFront(item)
 		return item.Value.(renderCacheEntry[K, V]).value, true
@@ -51,6 +55,8 @@ func (c *renderCache[K, V]) get(key K) (V, bool) {
 // put 缓存预算内的派生数据，超大单项不进入缓存
 // 入参: key 缓存键, value 缓存值, cost 字节成本
 func (c *renderCache[K, V]) put(key K, value V, cost int) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
 	if item := c.entries[key]; item != nil {
 		c.used -= item.Value.(renderCacheEntry[K, V]).cost
 		c.order.Remove(item)

ofdgo_renderer.go

@@ -18,10 +18,12 @@ import (
 	"context"
 	"image"
 	"io/fs"
+	"maps"
 )
 
 // Renderer 渲染器实现
 // 通过NewRenderer创建，实例及共享的Reader需串行使用
+// Fork创建独立任务实例，派生实例之间可并行渲染
 // 外部字体缺失且无可用回退时不绘制对应文字，其余内容继续；字体状态可通过FontInfos查询
 // 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，返回错误则停止，页数完成不代表写入成功
@@ -65,6 +67,31 @@ type Renderer struct {
 // RendererOption 渲染器配置选项
 type RendererOption func(*Renderer)
 
+// Fork 创建独立渲染实例，复用只读资源及线程安全的派生数据缓存
+// 创建过程需与原实例串行，输入生命周期遵循Reader.Fork，外部后端及字体文件系统需支持并行读取
+// 页面文字及导出进度回调不继承，取消上下文使用ctx
+// 入参: ctx 取消上下文
+// 返回: *Renderer 独立渲染器, error 准备或取消错误
+func (r *Renderer) Fork(ctx context.Context) (*Renderer, error) {
+	reader, err := r.Reader.Fork(ctx)
+	if err != nil {
+		return nil, err
+	}
+	next := NewRenderer(reader, WithDPI(r.DPI), WithAnnotations(r.RenderAnnotations), WithRenderBackends(r.backends), WithFontDirs(r.fontDirs...), WithFontFS(r.fontFS...))
+	next.Compression = r.Compression
+	next.DrawParams = maps.Clone(r.DrawParams)
+	next.CompositeGraphicUnits = maps.Clone(r.CompositeGraphicUnits)
+	next.OutputContext = ctx
+	next.TransparentBackground = r.TransparentBackground
+	next.decodeImages = r.decodeImages
+	next.imageCache = r.imageCache
+	next.fontDigests = r.fontDigests
+	next.fontPreparations = r.fontPreparations
+	next.fontMetrics = r.fontMetrics
+	next.glyphOutlines = r.glyphOutlines
+	return next, nil
+}
+
 // deviceLineWidth 按设备分辨率计算描边宽度，零线宽为一像素，正线宽至少为两像素
 // 入参: width 页面空间线宽，单位为毫米
 // 返回: float64 设备描边宽度，单位为毫米