mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-30 01:27:26 +08:00
349 lines
11 KiB
Go
349 lines
11 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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"bufio"
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"bytes"
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"compress/zlib"
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"context"
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"encoding/ascii85"
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"fmt"
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"image"
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"image/jpeg"
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"io"
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"math"
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"strconv"
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"github.com/tdewolff/canvas"
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"github.com/tdewolff/canvas/renderers/pdf"
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"github.com/tdewolff/canvas/renderers/ps"
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"github.com/tdewolff/canvas/renderers/svg"
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codecpdf "github.com/xiaoqidun/ofdgo/internal/codec/pdf"
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"github.com/xiaoqidun/pdfgo"
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)
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// canvasEPSWriter 在EPS头部写入本库制作软件，不改动绘图内容
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type canvasEPSWriter struct {
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io.Writer
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}
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// epsImageRenderer 在EPS输出端优化图片，不修改页面及渲染缓存
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type epsImageRenderer struct {
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*ps.PS
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writer io.Writer
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options CompressionOptions
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ctx context.Context
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err error
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}
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// RenderSVG 使用canvas输出SVG，按模式保留资源和对象分组
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// 入参: r 渲染器, page 页面内容, writer 输出流, mode 资源模式
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// 返回: SVGResources 外部资源, error 错误信息
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func (CanvasBackend) RenderSVG(r *Renderer, page *PageContent, writer io.Writer, mode SVGMode) (SVGResources, error) {
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switch mode {
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case SVGExternalFonts:
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return r.renderSVGResources(page, writer, false, false)
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case SVGExternalResources:
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return r.renderSVGResources(page, writer, true, false)
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case SVGObjects:
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return r.renderSVGResources(page, writer, true, true)
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case SVGEmbedded:
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c, err := r.renderCanvasPage(page)
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if err != nil {
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return SVGResources{}, err
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}
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buffer := bufio.NewWriter(writer)
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renderer := &svgResourceRenderer{SVG: svg.New(buffer, c.W, c.H, nil), renderer: r, writer: buffer, embeddedFonts: true}
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io.WriteString(buffer, svgCreatorMetadata)
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io.WriteString(buffer, `<g style="image-orientation:none">`)
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c.RenderTo(renderer)
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if renderer.err != nil {
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return SVGResources{}, renderer.err
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}
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io.WriteString(buffer, `</g>`)
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if err := renderer.Close(); err != nil {
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return SVGResources{}, err
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}
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return SVGResources{}, buffer.Flush()
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default:
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return SVGResources{}, fmt.Errorf("unsupported SVG mode %d", mode)
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}
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}
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// RenderEPS 使用canvas输出单页EPS
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// 入参: r 渲染器, page 页面内容, writer 输出流
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// 返回: error 错误信息
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func (CanvasBackend) RenderEPS(r *Renderer, page *PageContent, writer io.Writer) error {
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c, err := r.renderCanvasPage(page)
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if err != nil {
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return err
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}
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options := ps.DefaultOptions
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options.Format = ps.EncapsulatedPostScript
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buffer := bufio.NewWriter(writer)
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renderer := ps.New(canvasEPSWriter{buffer}, c.W, c.H, &options)
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if r.Compression.Mode == CompressionUnchanged {
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c.RenderTo(renderer)
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} else {
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optimized := &epsImageRenderer{PS: renderer, writer: buffer, options: r.Compression, ctx: r.outputContext()}
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c.RenderTo(optimized)
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if optimized.err != nil {
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return optimized.err
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}
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}
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if err := renderer.Close(); err != nil {
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return err
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}
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return buffer.Flush()
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}
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// Write 写入EPS片段并替换独立的制作软件声明
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// 入参: data EPS片段
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// 返回: int 已处理字节数, error 写入错误
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func (w canvasEPSWriter) Write(data []byte) (int, error) {
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if bytes.Equal(data, []byte("%%Creator: tdewolff/canvas\n")) {
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if _, err := io.WriteString(w.Writer, "%%Creator: "+ofdCreator+"\n"); err != nil {
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return 0, err
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}
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return len(data), nil
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}
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return w.Writer.Write(data)
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}
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// RenderPDF 使用canvas输出PDF，保留导航与文字并复用输出缓冲
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// 入参: r 渲染器, pages 页面列表, writer 输出流, progress 页面处理进度
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// 返回: error 错误信息
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func (CanvasBackend) RenderPDF(r *Renderer, pages []RenderDocumentPage, writer io.Writer, progress func(int, int) error) error {
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ctx := r.outputContext()
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if err := ctx.Err(); err != nil {
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return err
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}
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view := *r
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view.pageContext = ctx
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r = &view
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if len(pages) == 0 {
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return fmt.Errorf("no pages found")
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}
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doc := r.Reader.doc
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navigation, err := newPDFNavigation(r, doc, pages)
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if err != nil {
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return err
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}
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buf, direct := writer.(*bytes.Buffer)
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if r.Compression.Mode != CompressionUnchanged {
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direct = false
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}
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if !direct {
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buf = &bytes.Buffer{}
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}
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start := buf.Len()
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p := pdf.New(buf, pages[0].Box.W, pages[0].Box.H, nil)
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renderer := &pdfRenderer{PDF: p, glyphPaths: *resourceCache[*canvas.Path, *canvas.Path](r.Reader.resources, 16<<20), images: make([][]image.Image, 1), text: make([]codecpdf.TextPage, 1), navigation: navigation}
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defer func() {
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if renderer.imageError != nil {
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r.canvasState().images = *resourceCache[*EncodedImage, image.Image](r.Reader.resources, imageCacheLimit)
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}
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}()
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var info DocInfo
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if docInfo, err := r.Reader.DocInfo(); err == nil {
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info = *docInfo
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}
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renderer.information = make(pdfgo.Dictionary)
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for _, field := range []struct {
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key pdfgo.Name
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value string
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}{{"Title", info.Title}, {"Subject", info.Subject}, {"Author", info.Author}, {"Creator", ofdCreator}} {
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if field.value == "" {
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continue
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}
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encoded, err := pdfgo.EncodeTextString(field.value)
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if err != nil {
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buf.Truncate(start)
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return err
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}
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renderer.information[field.key] = encoded
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}
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for i, page := range pages {
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content, err := page.ReadContent(ctx, r.Reader)
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if err != nil {
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buf.Truncate(start)
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return fmt.Errorf("failed to read page %d: %w", i+1, err)
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}
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if err := navigation.addPage(r, i, content, pages); err != nil {
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buf.Truncate(start)
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return fmt.Errorf("failed to read page %d navigation: %w", i+1, err)
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}
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if i > 0 {
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p.NewPage(page.Box.W, page.Box.H)
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renderer.images = append(renderer.images, nil)
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renderer.text = append(renderer.text, codecpdf.TextPage{})
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}
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navigation.apply(p, i)
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if err := r.renderCanvasPageToContext(canvas.NewContext(renderer), content, !r.TransparentBackground); err != nil {
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buf.Truncate(start)
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return fmt.Errorf("failed to render page %d: %w", i+1, err)
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}
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if renderer.imageError != nil {
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buf.Truncate(start)
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return fmt.Errorf("failed to render page %d: %w", i+1, renderer.imageError)
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}
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pages[i].Content = nil
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if err := ctx.Err(); err != nil {
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buf.Truncate(start)
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return err
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}
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if progress != nil {
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if err := progress(i+1, len(pages)); err != nil {
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buf.Truncate(start)
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return err
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}
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}
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if err := ctx.Err(); err != nil {
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buf.Truncate(start)
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return err
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}
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}
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if doc != nil {
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if err := navigation.addOutlines(doc.Outlines.OutlineElem, 0, navigation.bookmarks, navigation.pageIndex, pages); err != nil {
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buf.Truncate(start)
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return err
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}
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}
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for index, outline := range navigation.Outline {
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p.AddOutline(strconv.Itoa(index), outline.Level, 0)
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}
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if err := p.Close(); err != nil {
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buf.Truncate(start)
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return err
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}
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data := buf.Bytes()[start:]
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options := pdfgo.OptimizeOptions{Compression: r.Compression}
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if r.Compression.Mode != CompressionUnchanged && progress != nil {
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options.OnProgress = func(_ string, _, _ int) error {
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return progress(len(pages), len(pages))
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}
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}
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if direct {
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var result bytes.Buffer
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err := renderer.writePDF(r.outputContext(), data, &result, options)
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buf.Truncate(start)
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if err != nil {
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return err
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}
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_, err = buf.Write(result.Bytes())
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return err
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}
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return renderer.writePDF(r.outputContext(), data, writer, options)
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}
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// RenderImage 写出Flate或更小的JPEG图片，保留显示尺寸与变换
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// 入参: img 图片, matrix 绘制变换
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func (r *epsImageRenderer) RenderImage(img image.Image, matrix canvas.Matrix) {
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if r.err != nil {
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return
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}
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if dpi := r.options.ImageDPI(); dpi > 0 {
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original := img.Bounds().Size()
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target := compressionImageSize(math.Hypot(matrix[0][0], matrix[1][0])*float64(original.X), math.Hypot(matrix[0][1], matrix[1][1])*float64(original.Y), dpi)
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img, r.err = pdfgo.ResizeImage(r.ctx, img, target)
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if r.err != nil {
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return
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}
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size := img.Bounds().Size()
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if size.X > 0 && size.Y > 0 {
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matrix = matrix.Scale(float64(original.X)/float64(size.X), float64(original.Y)/float64(size.Y))
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}
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}
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bounds := img.Bounds()
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width, height := bounds.Dx(), bounds.Dy()
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pixels := make([]byte, width*3)
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var encoded bytes.Buffer
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compressor, _ := zlib.NewWriterLevel(&encoded, zlib.BestCompression)
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opaque := true
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native, _ := img.(image.RGBA64Image)
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for y := 0; y < height; y++ {
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if r.err = r.ctx.Err(); r.err != nil {
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return
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}
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clear(pixels)
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for x := 0; x < width; x++ {
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if x&4095 == 0 {
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if r.err = r.ctx.Err(); r.err != nil {
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return
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}
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}
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var red, green, blue, alpha uint32
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if native != nil {
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pixel := native.RGBA64At(bounds.Min.X+x, bounds.Min.Y+y)
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red, green, blue, alpha = uint32(pixel.R), uint32(pixel.G), uint32(pixel.B), uint32(pixel.A)
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} else {
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red, green, blue, alpha = img.At(bounds.Min.X+x, bounds.Min.Y+y).RGBA()
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}
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if alpha != 65535 {
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opaque = false
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}
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if alpha == 65535 {
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offset := x * 3
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pixels[offset], pixels[offset+1], pixels[offset+2] = byte(red>>8), byte(green>>8), byte(blue>>8)
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} else if alpha != 0 {
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offset := x * 3
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pixels[offset], pixels[offset+1], pixels[offset+2] = byte(red*65535/alpha>>8), byte(green*65535/alpha>>8), byte(blue*65535/alpha>>8)
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}
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}
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if r.err = r.ctx.Err(); r.err != nil {
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return
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}
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if _, r.err = compressor.Write(pixels); r.err != nil {
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return
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}
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}
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if r.err = compressor.Close(); r.err != nil {
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return
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}
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data := encoded.Bytes()
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filter := "FlateDecode"
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if opaque && r.options.Mode == CompressionLossy {
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var candidate bytes.Buffer
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if r.err = jpeg.Encode(&candidate, img, &jpeg.Options{Quality: r.options.ImageQuality()}); r.err != nil {
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return
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}
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optimized, err := pdfgo.OptimizeJPEG(r.ctx, candidate.Bytes())
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if err != nil {
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r.err = err
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return
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}
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if len(optimized) < len(data) {
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data, filter = optimized, "DCTDecode"
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}
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}
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if r.err = r.ctx.Err(); r.err != nil {
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return
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}
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m := matrix.Scale(float64(width), float64(height))
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_, r.err = fmt.Fprintf(r.writer, " gsave /DeviceRGB setcolorspace [%s %s %s %s %s %s] concat <</ImageType 1 /BitsPerComponent 8 /Decode [0 1 0 1 0 1] /Interpolate true /Width %d /Height %d /ImageMatrix [%d 0 0 -%d 0 %d] /DataSource currentfile /ASCII85Decode filter /%s filter>>image\n", ofdNumber(m[0][0]), ofdNumber(m[1][0]), ofdNumber(m[0][1]), ofdNumber(m[1][1]), ofdNumber(m[0][2]), ofdNumber(m[1][2]), width, height, width, height, height, filter)
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if r.err != nil {
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return
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}
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writer := ascii85.NewEncoder(r.writer)
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if _, r.err = writer.Write(data); r.err != nil {
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return
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}
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if r.err = writer.Close(); r.err != nil {
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return
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}
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_, r.err = io.WriteString(r.writer, "~>\n grestore")
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}
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