mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-30 01:27:26 +08:00
250 lines
8.3 KiB
Go
250 lines
8.3 KiB
Go
// 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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"image"
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"math"
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)
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// compressionImages 记录图片各处使用的最大像素需求
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type compressionImages struct {
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ctx context.Context
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dpi int
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sizes map[string]image.Point
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renderer *Renderer
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patternPage *Matrix
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patterns map[*Pattern]bool
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patternVisits map[compressionPatternKey]bool
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}
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// compressionImagePlan 为有损输出分文档分析图片，按共享路径合并最大尺寸和保护条件
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// 入参: ctx 取消上下文, options 压缩配置
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// 返回: map[string]bool 可有损处理的路径, map[string]image.Point 像素需求, error 读取或取消错误
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func (r *Reader) compressionImagePlan(ctx context.Context, options CompressionOptions) (map[string]bool, map[string]image.Point, error) {
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if options.Mode != CompressionLossy {
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return nil, nil, ctx.Err()
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}
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images := make(map[string]bool)
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sizes := make(map[string]image.Point)
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blocked := make(map[string]bool)
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for index := 0; index < r.DocumentCount(); index++ {
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if err := ctx.Err(); err != nil {
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return nil, nil, err
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}
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document := r
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if index != r.DocumentIndex() {
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var err error
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document, err = r.DocumentContext(ctx, index)
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if err != nil {
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return nil, nil, err
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}
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}
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catalog, err := document.Images(ctx)
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if err != nil {
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if document != r {
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document.Close()
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}
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return nil, nil, err
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}
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var demands map[string]image.Point
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masks, geometry, err := document.compressionImageSafety(ctx, catalog)
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if err == nil && geometry {
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demands, err = document.compressionImageSizes(ctx, catalog, options.ImageDPI())
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}
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if document != r {
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document.Close()
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}
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if err != nil {
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return nil, nil, err
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}
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for _, img := range catalog {
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name := cleanPackagePath(img.Location)
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if old, ok := images[name]; !ok || old {
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images[name] = !masks[name]
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}
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size := demands[name]
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if size.X <= 0 || size.Y <= 0 || masks[name] {
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blocked[name] = true
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delete(sizes, name)
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continue
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}
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if !blocked[name] {
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old := sizes[name]
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sizes[name] = image.Pt(max(old.X, size.X), max(old.Y, size.Y))
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}
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}
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}
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return images, sizes, ctx.Err()
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}
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// compressionImageSize 将毫米显示尺寸换算为像素，非法尺寸不降采样
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// 整像素边界消除单位换算产生的单ULP上溢，不降低实际像素需求
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// 入参: width 显示宽度, height 显示高度, dpi 分辨率上限
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// 返回: image.Point 像素需求
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func compressionImageSize(width, height float64, dpi int) image.Point {
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w := math.Ceil(math.Nextafter(width*float64(dpi)/25.4, math.Inf(-1)))
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h := math.Ceil(math.Nextafter(height*float64(dpi)/25.4, math.Inf(-1)))
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if w <= 0 || h <= 0 || math.IsNaN(w) || math.IsNaN(h) || math.IsInf(w, 0) || math.IsInf(h, 0) || w > 1<<30 || h > 1<<30 {
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return image.Point{}
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}
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return image.Pt(int(w), int(h))
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}
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// compressionImageSizes 按正文、模板、注解及底纹的实际变换汇总图片尺寸，包括隐藏内容
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// 入参: ctx 取消上下文, images 图片资源, dpi 分辨率上限
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// 返回: map[string]image.Point 资源像素需求, error 取消错误
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func (r *Reader) compressionImageSizes(ctx context.Context, images []ImageInfo, dpi int) (map[string]image.Point, error) {
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if dpi == 0 {
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return nil, nil
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}
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doc, err := r.DocContext(ctx)
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if err != nil {
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return nil, ctx.Err()
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}
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renderer := NewRenderer(r, WithRenderBackends(RenderBackends{}))
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renderer.pageContext = ctx
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defer renderer.ClearCache()
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visitor := &compressionImages{ctx: ctx, dpi: dpi, sizes: make(map[string]image.Point), renderer: renderer}
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for _, ref := range doc.Pages.Page {
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if err := ctx.Err(); err != nil {
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return nil, err
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}
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page, err := r.PageContentContext(ctx, ref)
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if err != nil {
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return nil, ctx.Err()
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}
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for _, ref := range page.Template {
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if renderer.loadTemplate(ref.TemplateID) == nil {
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return nil, ctx.Err()
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}
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}
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if err := renderer.WalkPage(page, visitor); err != nil {
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return nil, ctx.Err()
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}
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}
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for _, ref := range r.doc.CommonData.TemplatePage {
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if err := ctx.Err(); err != nil {
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return nil, err
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}
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template := renderer.loadTemplate(ref.ID)
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if template == nil {
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return nil, ctx.Err()
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}
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for order := range 3 {
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if err := renderer.walkLayers(template.Content.Layer, order, visitor); err != nil {
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return nil, ctx.Err()
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}
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}
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}
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result := make(map[string]image.Point)
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for _, img := range images {
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name := cleanPackagePath(img.Location)
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size := visitor.sizes[editorResourceID(img.ID)]
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old := result[name]
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result[name] = image.Pt(max(old.X, size.X), max(old.Y, size.Y))
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}
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return result, ctx.Err()
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}
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// DrawObject 汇总图片、替换图及文字和路径底纹的尺寸，不使用裁剪后的局部面积
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// 入参: object 图形对象, state 继承状态
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// 返回: error 取消或几何错误
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func (v *compressionImages) DrawObject(object *GraphicObject, state RenderState) error {
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if err := v.ctx.Err(); err != nil {
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return err
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}
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switch object.Type {
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case "PathObject":
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return v.objectPatterns(object.PathObject, state)
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case "TextObject":
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text := object.TextObject
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return v.objectPatterns(PathObject{Boundary: text.Boundary, CTM: text.CTM, DrawParam: text.DrawParam, FillColor: text.FillColor, StrokeColor: text.StrokeColor}, state)
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case "ImageObject":
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default:
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return nil
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}
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img := object.ImageObject
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ids := [2]string{editorResourceID(img.ResourceID), editorResourceID(img.Substitution)}
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if ids[0] == "" || img.Substitution != "" && ids[1] == "" {
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return fmt.Errorf("invalid image resource")
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}
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box, err := ParseBox(img.Boundary)
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if err != nil {
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return err
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}
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local := NewMatrix(img.CTM)
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if img.CTM == "" {
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local = Matrix{a: box.W, d: box.H}
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}
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matrix, _ := renderObjectMatrix(img.Boundary, local, state)
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size := compressionImageSize(math.Hypot(matrix.a, matrix.b), math.Hypot(matrix.c, matrix.d), v.dpi)
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return v.recordSize(ids, size)
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}
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// VisitComposite 按矢量资源的完整变换统计缩略图和替换图，不以裁剪区域缩减尺寸
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// 入参: object 矢量资源或复合图元, state 已包含当前图元变换的状态
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// 返回: error 取消、资源标识或几何错误
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func (v *compressionImages) VisitComposite(object *CompositeGraphicUnit, state RenderState) error {
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if err := v.ctx.Err(); err != nil {
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return err
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}
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if object.Thumbnail == "" && object.Substitution == "" {
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return nil
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}
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ids := [2]string{editorResourceID(object.Thumbnail), editorResourceID(object.Substitution)}
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if object.Thumbnail != "" && ids[0] == "" || object.Substitution != "" && ids[1] == "" {
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return fmt.Errorf("invalid composite image resource")
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}
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matrix := IdentityMatrix
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if state.Parent != nil {
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matrix = *state.Parent
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}
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size := compressionImageSize(object.Width*math.Hypot(matrix.a, matrix.b), object.Height*math.Hypot(matrix.c, matrix.d), v.dpi)
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return v.recordSize(ids, size)
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}
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// recordSize 合并同一图像资源在不同位置的最大像素需求
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// 入参: ids 图像标识，空值不统计, size 当前像素需求
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// 返回: error 尺寸无效时返回错误
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func (v *compressionImages) recordSize(ids [2]string, size image.Point) error {
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if size.X == 0 || size.Y == 0 {
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return fmt.Errorf("invalid image placement")
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}
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for _, id := range ids {
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if id == "" {
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continue
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}
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old := v.sizes[id]
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v.sizes[id] = image.Pt(max(old.X, size.X), max(old.Y, size.Y))
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}
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return nil
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}
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// DrawStamp 保留签章内容，不参与图片降采样
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// 入参: stamp 印章
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// 返回: error 始终为空
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func (v *compressionImages) DrawStamp(stamp Stamp) error { return nil }
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// IncludeHidden 将隐藏内容纳入尺寸分析，保留图片在所有使用位置的精度
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// 返回: bool 始终为真
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func (v *compressionImages) IncludeHidden() bool { return true }
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// SkipClips 按完整图片尺寸分析，不加载裁剪几何或文字轮廓
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// 返回: bool 始终为真
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func (v *compressionImages) SkipClips() bool { return true }
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