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feat(文档导出): 优化大文档流式导出，降低内存占用
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xiaoqidun committed 2026-09-14 10:49:05 +08:00
1 parent ca8f22dba1
commit d3904521b9
5 files changed
+244 -99
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internal/webui/wasm.go
+77 -15
View File
@@ -17,11 +17,43 @@
package webui
import (
"bufio"
"encoding/json"
"fmt"
"syscall/js"
)
// exportWriter 分块传递导出数据
type exportWriter struct {
write js.Value
}
// Write 将数据块交给浏览器保存
// 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 {
return size - len(data), err
}
data = data[n:]
}
return size, nil
}
// currentSession 当前WebUI文档会话
var currentSession *Session
@@ -42,8 +74,8 @@ func RunWASM() {
registerCallback("ofdgoSVGFontData", svgFontData)
registerCallback("ofdgoSearchPage", searchPage)
registerCallback("ofdgoExportFormats", exportFormats)
registerCallback("ofdgoExportPage", exportPage)
registerCallback("ofdgoExportDocument", exportDocument)
registerExportCallback("ofdgoExportPage", exportPage)
registerExportCallback("ofdgoExportDocument", exportDocument)
registerCallback("ofdgoMatchFontFiles", matchFontFiles)
select {}
}
@@ -52,18 +84,42 @@ func RunWASM() {
// 入参: name 回调名称, fn 回调函数
func registerCallback(name string, fn func([]js.Value) (any, error)) {
cb := js.FuncOf(func(this js.Value, args []js.Value) any {
data, err := safeCall(fn, args)
if err != nil {
return encodeResult(apiResult{OK: false, Error: err.Error()})
}
if result, ok := data.(js.Value); ok {
return result
}
return encodeResult(apiResult{OK: true, Data: data})
return callbackResult(fn, args)
})
js.Global().Set(name, cb)
}
// registerExportCallback 异步导出，为浏览器处理数据块让出事件循环
// 入参: name 回调名称, fn 回调函数
func registerExportCallback(name string, fn func([]js.Value) (any, error)) {
cb := js.FuncOf(func(this js.Value, args []js.Value) any {
executor := js.FuncOf(func(this js.Value, callbacks []js.Value) any {
resolve := callbacks[0]
go func() {
resolve.Invoke(callbackResult(fn, args))
}()
return nil
})
defer executor.Release()
return js.Global().Get("Promise").New(executor)
})
js.Global().Set(name, cb)
}
// callbackResult 转换浏览器接口结果
// 入参: fn 回调函数, args 回调参数
// 返回: any 浏览器结果
func callbackResult(fn func([]js.Value) (any, error), args []js.Value) any {
data, err := safeCall(fn, args)
if err != nil {
return encodeResult(apiResult{OK: false, Error: err.Error()})
}
if result, ok := data.(js.Value); ok {
return result
}
return encodeResult(apiResult{OK: true, Data: data})
}
// safeCall 调用浏览器回调并转换异常
// 入参: fn 回调函数, args 回调参数
// 返回: any 回调结果, error 错误信息
@@ -238,15 +294,18 @@ func exportPage(args []js.Value) (any, error) {
if currentSession == nil {
return nil, fmt.Errorf("ofd document is not opened")
}
if len(args) < 3 {
if len(args) < 4 {
return nil, fmt.Errorf("missing export page arguments")
}
data, format, err := currentSession.ExportPage(args[0].Int(), args[1].String(), args[2].Float())
writer := bufio.NewWriterSize(exportWriter{write: args[3]}, 1<<20)
format, err := currentSession.ExportPage(args[0].Int(), args[1].String(), args[2].Float(), writer)
if err != nil {
return nil, err
}
if err := writer.Flush(); err != nil {
return nil, err
}
return successResult(map[string]any{
"bytes": bytesToJS(data),
"label": format.Label,
"mime": format.MIME,
}), nil
@@ -259,12 +318,15 @@ func exportDocument(args []js.Value) (any, error) {
if currentSession == nil {
return nil, fmt.Errorf("ofd document is not opened")
}
data, format, err := currentSession.ExportDocument(args[0].String(), args[1].Float())
writer := bufio.NewWriterSize(exportWriter{write: args[2]}, 1<<20)
format, err := currentSession.ExportDocument(args[0].String(), args[1].Float(), writer)
if err != nil {
return nil, err
}
if err := writer.Flush(); err != nil {
return nil, err
}
return successResult(map[string]any{
"bytes": bytesToJS(data),
"label": format.Label,
"mime": format.MIME,
}), nil
internal/webui/webui.go
+24 -71
View File
@@ -15,12 +15,10 @@
package webui
import (
"archive/zip"
"bytes"
"fmt"
"image/jpeg"
"io"
"path"
"strconv"
"strings"
"time"
@@ -450,38 +448,22 @@ func (s *Session) SVGFontData(name string) ([]byte, error) {
}
// ExportPage 导出单页
// 入参: index 页面索引, value 导出格式, dpi 图片DPI
// 返回: []byte 文件数据, ExportFormat 导出格式, error 错误信息
func (s *Session) ExportPage(index int, value string, dpi float64) ([]byte, ExportFormat, error) {
// 入参: index 页面索引, value 导出格式, dpi 图片DPI, writer 输出流
// 返回: ExportFormat 导出格式, error 错误信息
func (s *Session) ExportPage(index int, value string, dpi float64, writer io.Writer) (ExportFormat, error) {
format, ok := exportFormat(value)
if !ok {
return nil, ExportFormat{}, fmt.Errorf("unsupported export format %s", value)
return ExportFormat{}, fmt.Errorf("unsupported export format %s", value)
}
page, err := s.pageContent(index)
if err != nil {
return nil, ExportFormat{}, err
return ExportFormat{}, err
}
var buf bytes.Buffer
renderer := *s.Renderer
if dpi > 0 && (format.Value == "png" || format.Value == "jpg") {
renderer.DPI = dpi
}
switch format.Value {
case "svg":
err = renderer.RenderToSVG(page, &buf)
case "pdf":
err = renderer.RenderToPDF(page, &buf)
case "eps":
err = renderer.RenderToEPS(page, &buf)
case "png":
err = renderer.RenderToPNG(page, &buf)
case "jpg":
err = renderer.RenderToJPEG(page, &buf, &jpeg.Options{Quality: 95})
}
if err != nil {
return nil, ExportFormat{}, err
}
return buf.Bytes(), format, nil
return format, renderer.RenderTo(page, writer, format.Value)
}
// signatureInfos 获取签名验证信息
@@ -632,72 +614,43 @@ func signatureStampInfos(positions []ofdgo.SignatureStampPosition) []SignatureSt
}
// ExportDocument 导出文档为PDF或逐页打包ZIP
// 入参: value 导出格式, dpi 图片DPI
// 返回: []byte 文件数据, ExportFormat 导出格式, error 错误信息
func (s *Session) ExportDocument(value string, dpi float64) ([]byte, ExportFormat, error) {
// 入参: value 导出格式, dpi 图片DPI, writer 输出流
// 返回: ExportFormat 导出格式, error 错误信息
func (s *Session) ExportDocument(value string, dpi float64, writer io.Writer) (ExportFormat, error) {
format, ok := exportFormat(value)
if !ok {
return nil, ExportFormat{}, fmt.Errorf("unsupported export format %s", value)
return ExportFormat{}, fmt.Errorf("unsupported export format %s", value)
}
if format.Value == "pdf" {
data, err := s.ExportPDF()
return data, format, err
return format, s.ExportPDF(writer)
}
if s == nil || s.Reader == nil || s.Renderer == nil || s.doc == nil {
return nil, ExportFormat{}, fmt.Errorf("ofd document is not opened")
return ExportFormat{}, fmt.Errorf("ofd document is not opened")
}
count := len(s.doc.Pages.Page)
if count == 0 {
return nil, ExportFormat{}, fmt.Errorf("no pages found")
renderer := *s.Renderer
if dpi > 0 && (format.Value == "png" || format.Value == "jpg") {
renderer.DPI = dpi
}
var buf bytes.Buffer
archive := zip.NewWriter(&buf)
method := zip.Deflate
if format.Value == "png" || format.Value == "jpg" {
method = zip.Store
}
width := len(strconv.Itoa(count))
for index := range count {
data, _, err := s.ExportPage(index, format.Value, dpi)
if err != nil {
return nil, ExportFormat{}, fmt.Errorf("failed to export page %d: %w", index+1, err)
}
entry, err := archive.CreateHeader(&zip.FileHeader{
Name: fmt.Sprintf("%0*d.%s", width, index+1, format.Extension),
Method: method,
})
if err != nil {
return nil, ExportFormat{}, err
}
if _, err := entry.Write(data); err != nil {
return nil, ExportFormat{}, err
}
}
if err := archive.Close(); err != nil {
return nil, ExportFormat{}, err
}
return buf.Bytes(), ExportFormat{Value: "zip", Label: "ZIP", Extension: "zip", MIME: "application/zip"}, nil
err := renderer.RenderToZIP(writer, format.Value)
return ExportFormat{Value: "zip", Label: "ZIP", Extension: "zip", MIME: "application/zip"}, err
}
// ExportPDF 导出文档为PDF
// 返回: []byte PDF文件数据, error 错误信息
func (s *Session) ExportPDF() ([]byte, error) {
// 入参: writer 输出流
// 返回: error 错误信息
func (s *Session) ExportPDF(writer io.Writer) error {
if s == nil || s.Reader == nil || s.Renderer == nil || s.doc == nil {
return nil, fmt.Errorf("ofd document is not opened")
return fmt.Errorf("ofd document is not opened")
}
var buf bytes.Buffer
pages := make([]*ofdgo.PageContent, len(s.doc.Pages.Page))
for i := range pages {
page, err := s.pageContent(i)
if err != nil {
return nil, err
return err
}
pages[i] = page
}
if err := s.Renderer.RenderPagesToPDF(pages, &buf); err != nil {
return nil, err
}
return buf.Bytes(), nil
return s.Renderer.RenderPagesToPDF(pages, writer)
}
// pageContent 获取页面内容