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@@ -0,0 +1,292 @@
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// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ofdgo
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import (
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"context"
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"fmt"
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"maps"
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"mime"
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"strings"
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"github.com/xiaoqidun/pdfgo"
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)
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// screenAnnotation 转换屏幕注解的音视频呈现，不忽略必须遵守的播放器约束
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// 入参: ctx 取消上下文, page PDF页面, annotation 屏幕注解, strict 严格检查开关
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// 返回: error 动作、媒体或外观错误
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func (p *pdfImporter) screenAnnotation(ctx context.Context, page *pdfgo.Page, annotation pdfgo.Annotation, strict bool) error {
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if annotation.Dictionary["A"] == nil {
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return p.appearanceAnnotation(ctx, page, annotation)
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}
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appearance := annotation
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appearance.Dictionary = maps.Clone(annotation.Dictionary)
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delete(appearance.Dictionary, "A")
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if appearance.Dictionary["AP"] == nil {
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appearance.Dictionary["AP"] = pdfgo.Dictionary{"N": &pdfgo.Stream{Dictionary: pdfgo.Dictionary{
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"Type": pdfgo.Name("XObject"), "Subtype": pdfgo.Name("Form"), "BBox": pdfgo.Array{pdfgo.Integer(0), pdfgo.Integer(0), pdfgo.Integer(1), pdfgo.Integer(1)},
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}}}
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}
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fallback := func(reason string) error {
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if strict {
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return &pdfgo.UnsupportedError{Feature: reason}
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}
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p.warning(pdfgo.Diagnostic{Page: p.page + 1, Message: "PDF screen appearance retained; " + reason})
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delete(appearance.Dictionary, "AA")
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return p.appearanceAnnotation(ctx, page, appearance)
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}
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value, err := p.reader.Resolve(annotation.Dictionary["A"])
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if err != nil {
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return err
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}
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action, ok := value.(pdfgo.Dictionary)
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if !ok {
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return fmt.Errorf("invalid screen action")
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}
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subtype, err := p.reader.Resolve(action["S"])
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if err != nil {
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return err
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}
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operation, err := p.reader.Resolve(action["OP"])
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if err != nil {
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return err
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}
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if subtype != pdfgo.Name("Rendition") || operation != pdfgo.Integer(0) || action["Next"] != nil || annotation.Dictionary["AA"] != nil {
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return fallback("screen action cannot be represented in OFD")
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}
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if target, ok := action["AN"].(pdfgo.Reference); !ok || target != annotation.Reference || annotation.Dictionary["P"] != page.Reference {
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return fallback("screen action target is unavailable")
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}
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rendition, err := p.reader.ReadRendition(ctx, action["R"])
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if err != nil {
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if ctx.Err() != nil {
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return ctx.Err()
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}
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return fallback("media rendition unavailable: " + err.Error())
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}
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selected, err := rendition.Select(ctx, func(candidate *pdfgo.Rendition) (bool, error) {
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_, _, viable, err := p.nativeRendition(candidate)
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return viable, err
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})
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if err != nil {
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return err
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}
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if selected == nil {
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return fallback("no equivalent media rendition")
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}
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converted, kind, _, err := p.nativeRendition(selected)
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if err != nil {
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return err
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}
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data, available, err := p.mediaData(ctx, *selected.Clip.File)
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if err != nil {
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return err
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}
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if !available {
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return p.appearanceAnnotation(ctx, page, appearance)
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}
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format := pdfMediaFormat(*selected.Clip.File)
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if format == "" {
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mediaType, _, _ := mime.ParseMediaType(selected.Clip.ContentType)
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format = strings.TrimPrefix(strings.SplitN(mediaType, "/", 2)[1], "x-")
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}
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id, err := p.editor.AddMedia(kind, format, data)
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if err != nil {
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return err
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}
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if kind == "Audio" {
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converted.Sound.ResourceID = id
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} else {
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converted.Movie.ResourceID = id
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}
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if len(selected.Play) != 0 || len(selected.Screen) != 0 || len(selected.Clip.BestEffort) != 0 {
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p.report.Warnings = append(p.report.Warnings, pdfgo.Diagnostic{Page: p.page + 1, Message: "PDF media rendition converted; best-effort presentation preferences may differ in OFD"})
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}
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return p.appearanceAnnotation(ctx, page, appearance, converted)
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}
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// nativeRendition 检查可等价转换的媒体分支，视频不接受无法表达的音量及循环
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// 入参: rendition 媒体呈现或选择器
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// 返回: Action 播放动作, string 媒体类别, bool 是否可用, error 参数错误
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func (p *pdfImporter) nativeRendition(rendition *pdfgo.Rendition) (Action, string, bool, error) {
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result := Action{Event: "CLICK"}
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viable, err := p.renditionCriteria(rendition)
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if err != nil || !viable {
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return result, "", false, err
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}
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if rendition.Subtype == "SR" {
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return result, "", true, nil
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}
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clip := rendition.Clip
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if clip == nil || clip.Subtype != "MCD" || clip.File == nil || len(clip.MustHonor) != 0 || len(clip.Players) != 0 {
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return result, "", false, nil
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}
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if clip.File.Embedded == nil && p.resolveFile == nil {
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return result, "", false, nil
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}
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for key, object := range clip.Permissions {
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value, err := p.reader.Resolve(object)
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if err != nil {
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return result, "", false, err
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}
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if key == "Type" && value == pdfgo.Name("MediaPermissions") {
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continue
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}
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if key != "TF" {
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return result, "", false, nil
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}
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if _, ok := value.(pdfgo.String); !ok {
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return result, "", false, fmt.Errorf("invalid media temporary-file permission")
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}
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}
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mediaType, _, err := mime.ParseMediaType(clip.ContentType)
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if err != nil || !strings.HasPrefix(mediaType, "audio/") && !strings.HasPrefix(mediaType, "video/") {
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return result, "", false, nil
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}
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audio := strings.HasPrefix(mediaType, "audio/")
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play, viable, err := p.renditionParameters(rendition.Play, map[pdfgo.Name]func(pdfgo.Object) bool{
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"V": func(value pdfgo.Object) bool {
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number, ok := value.(pdfgo.Integer)
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return ok && number >= 0 && number <= 100 && (audio || number == 100)
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},
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"RC": func(value pdfgo.Object) bool {
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return value == pdfgo.Integer(1) || value == pdfgo.Real(1) || audio && (value == pdfgo.Integer(0) || value == pdfgo.Real(0))
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},
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"A": func(value pdfgo.Object) bool { return value == pdfgo.Boolean(true) },
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"F": func(value pdfgo.Object) bool { return value == pdfgo.Integer(0) || value == pdfgo.Integer(5) },
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})
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if err != nil || !viable {
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return result, "", false, err
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}
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_, viable, err = p.renditionParameters(rendition.Screen, map[pdfgo.Name]func(pdfgo.Object) bool{
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"W": func(value pdfgo.Object) bool { return value == pdfgo.Integer(3) },
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})
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if err != nil || !viable {
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return result, "", false, err
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}
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volume := 100
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if value := play["V"]; value != nil {
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volume = int(value.(pdfgo.Integer))
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}
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repeat := false
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if value := play["RC"]; value != nil && value != pdfgo.Integer(1) && value != pdfgo.Real(1) {
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repeat = true
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}
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if audio {
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result.Sound = &Sound{Volume: &volume, Repeat: repeat}
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return result, "Audio", true, nil
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}
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result.Movie = &Movie{Operator: "Play"}
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return result, "Video", true, nil
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}
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// renditionCriteria 检查媒体环境条件，未知尽力处理字段不影响候选可用性
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// 入参: rendition 媒体呈现或选择器
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// 返回: bool 是否可用, error 条件字典或引用错误
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func (p *pdfImporter) renditionCriteria(rendition *pdfgo.Rendition) (bool, error) {
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for _, constraints := range []struct {
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dict pdfgo.Dictionary
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required bool
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}{{rendition.MustHonor, true}, {rendition.BestEffort, false}} {
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for key, object := range constraints.dict {
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if key != "C" {
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if constraints.required {
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return false, nil
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}
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continue
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}
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value, err := p.reader.Resolve(object)
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if err != nil {
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return false, err
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}
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criteria, ok := value.(pdfgo.Dictionary)
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if !ok {
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return false, fmt.Errorf("invalid media criteria")
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}
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for name, object := range criteria {
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value, err := p.reader.Resolve(object)
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if err != nil {
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return false, err
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}
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if name == "Type" && value == pdfgo.Name("MediaCriteria") {
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continue
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}
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switch name {
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case "Type", "A", "C", "O", "S", "R", "D", "Z", "V", "P", "L":
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return false, nil
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default:
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if constraints.required {
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return false, nil
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}
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}
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}
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}
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}
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return true, nil
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}
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// renditionParameters 合并可等价表达的播放参数，不支持的偏好不阻断播放
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// 入参: dict 参数字典, supported 字段及可表达值的检查
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// 返回: pdfgo.Dictionary 合并后的值, bool 是否可用, error 字典或引用错误
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func (p *pdfImporter) renditionParameters(dict pdfgo.Dictionary, supported map[pdfgo.Name]func(pdfgo.Object) bool) (pdfgo.Dictionary, bool, error) {
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values := make(pdfgo.Dictionary)
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for key := range dict {
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if key != "Type" && key != "MH" && key != "BE" {
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return nil, false, nil
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}
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}
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value, err := p.reader.Resolve(dict["MH"])
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if err != nil {
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return nil, false, err
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}
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mandatory, _ := value.(pdfgo.Dictionary)
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for _, key := range []pdfgo.Name{"BE", "MH"} {
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value, err := p.reader.Resolve(dict[key])
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if err != nil {
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return nil, false, err
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}
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if value == nil {
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continue
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}
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parameters, ok := value.(pdfgo.Dictionary)
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if !ok {
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return nil, false, fmt.Errorf("invalid media playback constraints")
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}
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for name, object := range parameters {
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if _, overridden := mandatory[name]; key == "BE" && overridden {
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continue
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}
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check := supported[name]
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if check == nil {
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if key == "MH" {
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return nil, false, nil
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}
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continue
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}
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resolved, err := p.reader.Resolve(object)
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if err != nil {
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return nil, false, err
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}
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if !check(resolved) {
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if key == "MH" {
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return nil, false, nil
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}
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continue
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}
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values[name] = resolved
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}
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}
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return values, true, nil
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}
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Reference in new issue
Block a user