Files
ofdgo/ofdgo_compression_resources.go
T
2026-10-08 01:06:43 +08:00

334 lines
9.8 KiB
Go

// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ofdgo
import (
"bytes"
"crypto/sha256"
"encoding/xml"
"fmt"
"image"
"io"
"maps"
"path"
"slices"
"strings"
"github.com/xiaoqidun/pdfgo"
)
// outputImageKey 区分相同图像的压缩配置和像素需求,不跨写出保留状态
type outputImageKey struct {
hash [32]byte
options CompressionOptions
size image.Point
}
// compressResourceParts 优化输出图片并合并相同资源文件,保留资源标识及各自属性
// 入参: parts 输出改动, reader 原包,可为空, removed 已移除条目
// 返回: error 读取或取消错误
func (e *Editor) compressResourceParts(parts map[string][]byte, reader *Reader, removed map[string]bool) error {
return e.compressResourceReferences(parts, reader, removed, nil)
}
// compressResourceReferences 优化资源,复用自产页面引用并流式读取暂存页面
// 入参: parts 输出改动, reader 原包, removed 已移除条目, generated 本次自产页面及引用
// 返回: error 读取或取消错误
func (e *Editor) compressResourceReferences(parts map[string][]byte, reader *Reader, removed map[string]bool, generated map[string]editorGeneratedReferences) error {
if e.output == nil || e.output.options.Mode == CompressionUnchanged || e.output.protected {
return nil
}
generated = e.generatedVectorReferences(parts, generated)
names := make(map[string]bool)
if reader != nil {
for name := range reader.fileIndex {
names[name] = true
}
for name := range reader.files {
names[name] = true
}
}
for name := range parts {
names[name] = true
}
read := func(name string) ([]byte, error) {
if data, ok := parts[name]; ok {
return data, nil
}
return reader.readFileView(name)
}
refs := editorResourceRefs{ids: make(map[string]bool), files: make(map[string]bool), fonts: make(map[string]*editorFontUsage)}
var resources []string
actual := make(map[string]string)
for _, name := range slices.Sorted(maps.Keys(names)) {
if err := e.output.ctx.Err(); err != nil {
return err
}
key := strings.ToLower(cleanPackagePath(name))
if removed[key] || strings.HasSuffix(name, "/") {
continue
}
if prior, ok := actual[key]; ok && prior != name {
return nil
}
actual[key] = name
data, replaced := parts[name]
if known, ok := generated[name]; ok && replaced && known.refs != nil && known.matches(data) {
refs.merge(known.refs)
continue
}
var input io.ReadCloser
if replaced {
if known := generated[name]; data == nil && known.staged != nil {
input = known.staged.open()
} else {
input = io.NopCloser(bytes.NewReader(data))
}
} else {
var err error
input, err = reader.openFile(name)
if err != nil {
return err
}
}
resource, safe := refs.scan(imageInput{ReadCloser: input, context: e.output.ctx}, name)
input.Close()
if err := e.output.ctx.Err(); err != nil {
return err
}
if !safe {
return nil
}
if resource {
resources = append(resources, name)
}
}
type resourceFile struct{ key, role string }
files := make(map[resourceFile]bool)
for _, name := range resources {
data, err := read(name)
if err != nil {
return err
}
root, err := parseEditorXML(data)
if err != nil {
return err
}
for _, group := range root.children {
for _, node := range group.children {
field := ""
if group.name.Local == "Fonts" && node.name.Local == "Font" {
field = "FontFile"
}
if group.name.Local == "MultiMedias" && node.name.Local == "MultiMedia" {
field = "MediaFile"
}
if field == "" {
continue
}
file := node.child(field)
if file == nil {
continue
}
var value string
if err := xml.Unmarshal(data[file.start:file.end], &value); err != nil {
return err
}
key := editorResourceLocation(name, root.attr("BaseLoc"), value)
if field == "MediaFile" && node.attr("Type") != "Image" {
refs.files[key] = true
continue
}
if key != strings.ToLower(cleanPackagePath(resolveResourcePath(name, root.attr("BaseLoc"), value))) {
return nil
}
if actual[key] != "" && !refs.files[key] {
files[resourceFile{key, field}] = true
}
}
}
}
aliases := make(map[string]string)
locations := maps.Clone(actual)
reserved := make(map[string]bool, len(actual))
for key := range actual {
reserved[key] = true
}
formats := make(map[string]string)
seen := make(map[string]map[[32]byte]string)
imageResults := make(map[outputImageKey][]byte)
ordered := slices.Sorted(maps.Keys(actual))
var imageKeys []string
for _, key := range ordered {
if !refs.files[key] && files[resourceFile{key, "MediaFile"}] && !files[resourceFile{key, "FontFile"}] {
imageKeys = append(imageKeys, key)
}
}
load := func(key string) ([]byte, error) {
if data, ok := parts[actual[key]]; ok && len(data) > outputOptimizationBufferLimit {
return nil, nil
}
if reader != nil && parts[actual[key]] == nil {
if file, ok := reader.packageFile(actual[key]); ok && file.UncompressedSize64 > outputOptimizationBufferLimit {
return nil, nil
}
}
data, err := read(actual[key])
if len(data) > outputOptimizationBufferLimit {
return nil, nil
}
return data, err
}
if err := e.prepareOutputImages(imageKeys, load, imageResults); err != nil {
return err
}
for _, key := range ordered {
if refs.files[key] || files[resourceFile{key, "FontFile"}] && files[resourceFile{key, "MediaFile"}] {
continue
}
for _, role := range []string{"FontFile", "MediaFile"} {
if !files[resourceFile{key, role}] {
continue
}
if err := editorProgress(e.OnWriteProgress).report("compress", e.output.completed, 0); err != nil {
return err
}
if data, ok := parts[actual[key]]; ok && len(data) > outputOptimizationBufferLimit {
continue
}
if reader != nil && parts[actual[key]] == nil {
if file, ok := reader.packageFile(actual[key]); ok && file.UncompressedSize64 > outputOptimizationBufferLimit {
continue
}
}
data, err := read(actual[key])
if err != nil {
return err
}
if len(data) > outputOptimizationBufferLimit {
continue
}
if role == "MediaFile" {
options, demand := e.outputImageOptions(key)
cacheKey := outputImageKey{hash: sha256.Sum256(data), options: options, size: demand}
candidate, cached := imageResults[cacheKey]
var err error
if !cached {
candidate, err = pdfgo.OptimizeImageResource(e.output.ctx, data, options, demand)
if err == nil {
imageResults[cacheKey] = nil
if len(candidate) < len(data) {
imageResults[cacheKey] = candidate
}
}
}
if err != nil {
if e.output.ctx.Err() != nil {
return e.output.ctx.Err()
}
} else if candidate != nil && len(candidate) < len(data) {
data = candidate
parts[actual[key]] = data
}
if bytes.HasPrefix(data, []byte{255, 216}) {
formats[key] = "JPEG"
ext := path.Ext(actual[key])
if !strings.EqualFold(ext, ".jpg") && !strings.EqualFold(ext, ".jpeg") {
stem := strings.TrimSuffix(actual[key], ext)
name := stem + ".jpg"
for n := 1; reserved[strings.ToLower(name)]; n++ {
name = fmt.Sprintf("%s-%d.jpg", stem, n)
}
reserved[strings.ToLower(name)] = true
locations[key] = name
parts[name] = data
delete(parts, actual[key])
removed[key] = true
}
}
}
if seen[role] == nil {
seen[role] = make(map[[32]byte]string)
}
hash := sha256.Sum256(data)
if first, ok := seen[role][hash]; ok {
aliases[key] = first
removed[key] = true
if locations[key] != actual[key] {
delete(parts, locations[key])
}
} else {
seen[role][hash] = key
}
}
}
for _, name := range resources {
data, err := read(name)
if err != nil {
return err
}
root, err := parseEditorXML(data)
if err != nil {
return err
}
var patches []editorXMLPatch
for _, group := range root.children {
for _, node := range group.children {
for _, field := range []string{"FontFile", "MediaFile"} {
file := node.child(field)
if file == nil {
continue
}
var value string
if err := xml.Unmarshal(data[file.start:file.end], &value); err != nil {
return err
}
key := editorResourceLocation(name, root.attr("BaseLoc"), value)
fragment := data[node.start:node.end]
location := locations[key]
if first, ok := aliases[key]; ok {
location = locations[first]
}
if location != "" && location != actual[key] {
var escaped bytes.Buffer
xml.EscapeText(&escaped, []byte("/"+location))
patch := editorXMLContent(data, file, escaped.Bytes())
patch.start -= node.start
patch.end -= node.start
fragment = editorPatchXML(fragment, []editorXMLPatch{patch})
}
if field == "MediaFile" && formats[key] != "" && node.attr("Format") != formats[key] {
parsed, err := parseEditorXML(fragment)
if err != nil {
return err
}
fragment, err = editorXMLAttribute(fragment, parsed, "Format", formats[key])
if err != nil {
return err
}
}
if !bytes.Equal(fragment, data[node.start:node.end]) {
patches = append(patches, editorXMLPatch{start: node.start, end: node.end, data: fragment})
}
}
}
}
if len(patches) > 0 {
parts[name] = editorPatchXML(data, patches)
}
}
return e.output.ctx.Err()
}