feat(能力完善): 完善转换保真，修复交互缺陷

2026-10-29 13:56:32 +08:00 · 2026-10-10 09:48:05 +08:00
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commit 0ad2bda1f7
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+// 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 (
+	"errors"
+	"reflect"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// pdfRenditionImport 保存可转换事件中的屏幕关联，首次遇到呈现动作时建立
+type pdfRenditionImport struct {
+	actions map[pdfgo.Reference][]pdfgo.Dictionary
+	media   map[pdfgo.Reference][]pdfRenditionResource
+	err     error
+}
+
+// pdfRenditionResource 保存屏幕候选媒体及其独立控制标识
+type pdfRenditionResource struct {
+	ID   string
+	Kind string
+}
+
+// pdfRenditionAssignment 区分同一屏幕的呈现定义，重复触发不重复登记
+type pdfRenditionAssignment struct {
+	Screen    pdfgo.Reference
+	Rendition uintptr
+}
+
+// renditionControls 生成屏幕关联的控制序列，切换时不停止即将重新播放的资源
+// 入参: screen 屏幕引用, operation 停止、暂停或恢复操作, playing 即将播放的资源，控制动作为空, strict 是否禁止语义损失
+// 返回: []Action 控制序列，nil表示无法转换, error 资源或严格模式错误
+func (p *pdfImporter) renditionControls(screen pdfgo.Reference, operation int64, playing string, strict bool) ([]Action, error) {
+	if p.renditions == nil {
+		p.renditions = &pdfRenditionImport{actions: make(map[pdfgo.Reference][]pdfgo.Dictionary), media: make(map[pdfgo.Reference][]pdfRenditionResource)}
+		p.renditions.err = p.collectRenditions()
+	}
+	if err := p.ctx.Err(); err != nil {
+		return nil, err
+	}
+	if p.renditions.err != nil {
+		return nil, p.renditionActionLoss("screen associations cannot be determined: "+p.renditions.err.Error(), strict)
+	}
+	resources, err := p.renditionResources(screen, strict)
+	if err != nil {
+		return nil, err
+	}
+	for _, resource := range resources {
+		if resource.Kind != "Video" && (playing == "" || len(resources) > 1) {
+			return nil, p.renditionActionLoss("audio rendition control cannot be represented by OFD Sound", strict)
+		}
+	}
+	operator := map[int64]string{1: "Stop", 2: "Pause", 3: "Resume"}[operation]
+	actions := make([]Action, 0, len(resources))
+	for _, resource := range resources {
+		if resource.ID != playing {
+			actions = append(actions, Action{Event: "CLICK", Movie: &Movie{ResourceID: resource.ID, Operator: operator}})
+		}
+	}
+	return actions, nil
+}
+
+// renditionResources 解析一个屏幕的可用媒体，文件数据仅在该屏幕参与转换时读取
+// 入参: screen 屏幕引用, strict 是否禁止忽略无效动作
+// 返回: []pdfRenditionResource 候选媒体, error 解析、资源或取消错误
+func (p *pdfImporter) renditionResources(screen pdfgo.Reference, strict bool) ([]pdfRenditionResource, error) {
+	if resources, exists := p.renditions.media[screen]; exists {
+		return resources, nil
+	}
+	resources := make([]pdfRenditionResource, 0)
+	seen := make(map[string]bool)
+	for _, object := range p.renditions.actions[screen] {
+		playback, err := p.reader.ReadRenditionPlayback(p.ctx, object)
+		if err != nil {
+			if !strict && errors.Is(err, pdfgo.ErrInvalidAction) {
+				continue
+			}
+			return nil, err
+		}
+		if _, exists := p.pages[playback.Page]; !exists {
+			continue
+		}
+		selected, err := playback.Rendition.Select(p.ctx, func(candidate *pdfgo.Rendition) (bool, error) {
+			_, _, viable, err := p.nativeRendition(candidate)
+			return viable, err
+		})
+		if err != nil {
+			return nil, err
+		}
+		if selected == nil {
+			continue
+		}
+		_, kind, _, err := p.nativeRendition(selected)
+		if err != nil {
+			return nil, err
+		}
+		id, err := p.renditionResource(selected, kind, playback)
+		if err != nil {
+			return nil, err
+		}
+		if id != "" && !seen[id] {
+			seen[id] = true
+			resources = append(resources, pdfRenditionResource{ID: id, Kind: kind})
+		}
+	}
+	p.renditions.media[screen] = resources
+	return resources, p.ctx.Err()
+}
+
+// collectRenditions 索引可转换事件中的媒体关联，不解码媒体或执行脚本
+// 返回: error 动作结构、引用或取消错误
+func (p *pdfImporter) collectRenditions() error {
+	seen := make(map[pdfRenditionAssignment]bool)
+	collect := func(object pdfgo.Object) error {
+		return p.reader.WalkActions(p.ctx, object, func(info pdfgo.ActionInfo) error {
+			if info.Type != "Rendition" {
+				return nil
+			}
+			value, err := p.reader.Resolve(info.Dictionary["OP"])
+			if err != nil {
+				return err
+			}
+			if value != pdfgo.Integer(0) && value != pdfgo.Integer(4) {
+				return nil
+			}
+			screen, ok := info.Dictionary["AN"].(pdfgo.Reference)
+			if !ok {
+				return nil
+			}
+			value, err = p.reader.Resolve(info.Dictionary["R"])
+			if err != nil {
+				return err
+			}
+			r, ok := value.(pdfgo.Dictionary)
+			if !ok || r == nil {
+				return nil
+			}
+			key := pdfRenditionAssignment{Screen: screen, Rendition: reflect.ValueOf(r).Pointer()}
+			if !seen[key] {
+				seen[key] = true
+				p.renditions.actions[screen] = append(p.renditions.actions[screen], info.Dictionary)
+			}
+			return nil
+		})
+	}
+	opened, err := p.reader.ReadOpenAction(p.ctx)
+	if err != nil && !errors.Is(err, pdfgo.ErrInvalidDestination) {
+		return err
+	}
+	if opened.Action != nil {
+		if err := collect(opened.Action); err != nil {
+			return err
+		}
+	}
+	if err := p.reader.WalkOutlines(p.ctx, func(_ int, item pdfgo.OutlineItem) error {
+		return collect(item.Action)
+	}); err != nil {
+		return err
+	}
+	for _, page := range p.pageOrder {
+		triggers, err := p.reader.ReadPageTriggers(p.ctx, page)
+		if err != nil {
+			return err
+		}
+		for _, trigger := range triggers {
+			if trigger.Event == "O" {
+				if err := collect(trigger.Action); err != nil {
+					return err
+				}
+			}
+		}
+		annotations, err := page.AnnotationsContext(p.ctx)
+		if err != nil {
+			return err
+		}
+		for _, annotation := range annotations {
+			flags, err := p.reader.ReadAnnotationFlags(annotation)
+			if err != nil {
+				return err
+			}
+			if flags&64 == 0 && (annotation.Subtype == "Screen" || annotation.Subtype == "Link") {
+				if err := collect(annotation.Dictionary["A"]); err != nil {
+					return err
+				}
+			}
+			triggers, err := p.reader.ReadAnnotationTriggers(p.ctx, annotation)
+			if err != nil {
+				return err
+			}
+			for _, trigger := range triggers {
+				if trigger.Event == "PO" || trigger.Event == "U" && flags&64 == 0 && annotation.Subtype != "Widget" {
+					if err := collect(trigger.Action); err != nil {
+						return err
+					}
+				}
+			}
+		}
+	}
+	return p.ctx.Err()
+}