feat(正式发布): 实现了OFD渲染和导出为PDF、图片、矢量图等

2026-08-30 12:12:40 +08:00 · 2025-12-30 00:53:37 +08:00
parent 9f14eec058
commit 2e8b65b0a3
13 changed files with 1793 additions and 1 deletions
@@ -0,0 +1,576 @@
+// Copyright 2025 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 首款原生、全平台兼容的纯 Go 语言 OFD 渲染库
+package ofdgo
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"image/color"
+	"io"
+	"io/fs"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/tdewolff/canvas"
+	"github.com/tdewolff/canvas/renderers"
+	"github.com/tdewolff/canvas/renderers/pdf"
+	"github.com/tdewolff/canvas/renderers/rasterizer"
+)
+
+// Renderer 渲染器实现
+type Renderer struct {
+	Reader     *Reader
+	DPI        float64
+	fontFamily *canvas.FontFamily
+	DrawParams map[string]*DrawParam
+	FontMap    map[string]*canvas.FontFamily
+	fontDirs   []string
+	fontFS     []fs.FS
+}
+
+// RendererOption 渲染器配置选项
+type RendererOption func(*Renderer)
+
+// RenderPage 渲染特定页面内容
+// 入参: page 页面内容
+// 返回: *canvas.Canvas 画布实例, err 错误信息
+func (r *Renderer) RenderPage(page *PageContent) (*canvas.Canvas, error) {
+	boxStr := page.Area.PhysicalBox
+	if boxStr == "" {
+		boxStr = page.Area.ApplicationBox
+	}
+	if boxStr == "" {
+		boxStr = page.Area.ContentBox
+	}
+	if boxStr == "" && r.Reader.doc != nil {
+		boxStr = r.Reader.doc.CommonData.PageArea.PhysicalBox
+	}
+	if boxStr == "" {
+		boxStr = "0 0 210 297"
+	}
+	box, err := ParseBox(boxStr)
+	if err != nil {
+		return nil, err
+	}
+	c := canvas.New(box.W, box.H)
+	ctx := canvas.NewContext(c)
+	pageH := box.H
+	ctx.SetFillColor(canvas.White)
+	ctx.DrawPath(0, 0, canvas.Rectangle(box.W, box.H))
+	if len(page.Template) > 0 && r.Reader.doc != nil {
+		for _, tplRef := range page.Template {
+			r.renderTemplate(ctx, tplRef.TemplateID, pageH)
+		}
+	}
+	if page.Content.Layer != nil {
+		for _, layer := range page.Content.Layer {
+			r.renderLayer(ctx, layer, pageH, nil, nil, 0)
+		}
+	}
+	return c, nil
+}
+
+// RenderPageByIndex 按索引渲染页面
+// 入参: index 页面索引
+// 返回: *canvas.Canvas 画布实例, err 错误信息
+func (r *Renderer) RenderPageByIndex(index int) (*canvas.Canvas, error) {
+	doc, err := r.Reader.Doc()
+	if err != nil {
+		return nil, err
+	}
+	if index < 0 || index >= len(doc.Pages.Page) {
+		return nil, fmt.Errorf("page index %d out of range", index)
+	}
+	page, err := r.Reader.PageContent(doc.Pages.Page[index])
+	if err != nil {
+		return nil, err
+	}
+	return r.RenderPage(page)
+}
+
+// RenderToImage 渲染为光栅图
+// 入参: page 页面内容
+// 返回: image.Image 图像对象, err 错误信息
+func (r *Renderer) RenderToImage(page *PageContent) (image.Image, error) {
+	c, err := r.RenderPage(page)
+	if err != nil {
+		return nil, err
+	}
+	dpmm := r.DPI / 25.4
+	return rasterizer.Draw(c, canvas.DPMM(dpmm), canvas.DefaultColorSpace), nil
+}
+
+// RenderToSVG 渲染为SVG
+// 入参: page 页面内容, writer 输出流
+// 返回: err 错误信息
+func (r *Renderer) RenderToSVG(page *PageContent, writer io.Writer) error {
+	c, err := r.RenderPage(page)
+	if err != nil {
+		return err
+	}
+	return c.Write(writer, renderers.SVG())
+}
+
+// RenderToPDF 渲染为PDF
+// 入参: page 页面内容, writer 输出流
+// 返回: err 错误信息
+func (r *Renderer) RenderToPDF(page *PageContent, writer io.Writer) error {
+	c, err := r.RenderPage(page)
+	if err != nil {
+		return err
+	}
+	return c.Write(writer, renderers.PDF())
+}
+
+// RenderToEPS 渲染为EPS
+// 入参: page 页面内容, writer 输出流
+// 返回: err 错误信息
+func (r *Renderer) RenderToEPS(page *PageContent, writer io.Writer) error {
+	c, err := r.RenderPage(page)
+	if err != nil {
+		return err
+	}
+	return c.Write(writer, renderers.EPS())
+}
+
+// RenderToMultiPagePDF 将整个文档导出为多页PDF
+// 入参: writer 输出流
+// 返回: error 错误信息
+func (r *Renderer) RenderToMultiPagePDF(writer io.Writer) error {
+	doc, err := r.Reader.Doc()
+	if err != nil {
+		return err
+	}
+	if len(doc.Pages.Page) == 0 {
+		return fmt.Errorf("no pages found")
+	}
+	var p *pdf.PDF
+	for i, pgRef := range doc.Pages.Page {
+		page, err := r.Reader.PageContent(pgRef)
+		if err != nil {
+			continue
+		}
+		c, err := r.RenderPage(page)
+		if err != nil {
+			continue
+		}
+		if i == 0 {
+			p = pdf.New(writer, c.W, c.H, nil)
+		} else {
+			p.NewPage(c.W, c.H)
+		}
+		c.RenderTo(p)
+	}
+	if p == nil {
+		return fmt.Errorf("failed to render any page")
+	}
+	return p.Close()
+}
+
+// renderTemplate 渲染模板
+// 入参: ctx 画布上下文, templateID 模板ID, pageH 页面高度
+func (r *Renderer) renderTemplate(ctx *canvas.Context, templateID string, pageH float64) {
+	var tplPage *TemplatePage
+	for _, tp := range r.Reader.doc.CommonData.TemplatePage {
+		if tp.ID == templateID {
+			tplPage = &tp
+			break
+		}
+	}
+	if tplPage == nil {
+		return
+	}
+	tplContent, err := r.Reader.PageContent(Page{BaseLoc: tplPage.BaseLoc})
+	if err != nil {
+		return
+	}
+	if tplContent.Content.Layer != nil {
+		for _, layer := range tplContent.Content.Layer {
+			r.renderLayer(ctx, layer, pageH, nil, nil, 0)
+		}
+	}
+}
+
+// renderLayer 渲染图层
+// 入参: ctx 画布上下文, layer 图层对象, pageH 页面高度, defaultFill 默认填充色, defaultStroke 默认描边色, defaultLW 默认线宽
+func (r *Renderer) renderLayer(ctx *canvas.Context, layer Layer, pageH float64, defaultFill color.Color, defaultStroke color.Color, defaultLW float64) {
+	if layer.DrawParam != "" {
+		if dp := r.getDrawParam(layer.DrawParam, nil); dp != nil {
+			if dp.LineWidth > 0 {
+				defaultLW = dp.LineWidth
+			}
+			if dp.FillColor != nil {
+				defaultFill = parseColor(dp.FillColor.Value)
+			}
+			if dp.StrokeColor != nil {
+				defaultStroke = parseColor(dp.StrokeColor.Value)
+			}
+		}
+	}
+	for _, imgObj := range layer.ImageObject {
+		r.renderImage(ctx, imgObj, pageH)
+	}
+	for _, pathObj := range layer.PathObject {
+		r.renderPath(ctx, pathObj, pageH, defaultFill, defaultStroke, defaultLW)
+	}
+	for _, textObj := range layer.TextObject {
+		r.renderText(ctx, textObj, pageH, defaultFill, defaultStroke)
+	}
+}
+
+// getDrawParam 获取绘制参数逻辑
+// 入参: id 参数ID, visited 访问记录
+// 返回: *DrawParam 绘制参数
+func (r *Renderer) getDrawParam(id string, visited map[string]bool) *DrawParam {
+	if visited == nil {
+		visited = make(map[string]bool)
+	}
+	if visited[id] {
+		return nil
+	}
+	visited[id] = true
+	if dp, ok := r.DrawParams[id]; ok {
+		if dp.Relative != "" {
+			base := r.getDrawParam(dp.Relative, visited)
+			if base == nil {
+				return dp
+			}
+			merged := *base
+			if dp.LineWidth > 0 {
+				merged.LineWidth = dp.LineWidth
+			}
+			if dp.FillColor != nil {
+				merged.FillColor = dp.FillColor
+			}
+			if dp.StrokeColor != nil {
+				merged.StrokeColor = dp.StrokeColor
+			}
+			return &merged
+		}
+		return dp
+	}
+	return nil
+}
+
+// initCommon 初始化公共资源
+func (r *Renderer) initCommon() {
+	r.fontFamily = canvas.NewFontFamily("default")
+	sysFonts := []string{
+		"SimHei", "Microsoft YaHei", "SimSun", "KaiTi", "FangSong",
+		"Arial", "Segoe UI", "Times New Roman",
+	}
+	for _, name := range sysFonts {
+		if err := r.fontFamily.LoadSystemFont(name, canvas.FontRegular); err == nil {
+			break
+		}
+	}
+}
+
+// renderImage 渲染图片
+// 入参: ctx 画布上下文, obj 图片对象, pageH 页面高度
+func (r *Renderer) renderImage(ctx *canvas.Context, obj ImageObject, pageH float64) {
+	resPath, ok := r.Reader.ResMap[obj.ResourceID]
+	if !ok {
+		return
+	}
+	imgData, err := r.Reader.ResData(resPath)
+	if err != nil {
+		return
+	}
+	img, _, err := image.Decode(bytes.NewReader(imgData))
+	if err != nil {
+		return
+	}
+	box, _ := ParseBox(obj.Boundary)
+	imgBounds := img.Bounds()
+	imgW, imgH := float64(imgBounds.Dx()), float64(imgBounds.Dy())
+	if imgW <= 0 || imgH <= 0 {
+		return
+	}
+	ctm := NewMatrix(obj.CTM)
+	if obj.CTM == "" {
+		ctm = Matrix{a: box.W, d: box.H}
+	}
+	tx, ty := ctm.Transform(0, 1)
+	canvasX, canvasY := tx+box.X, pageH-(ty+box.Y)
+	ctx.Push()
+	ctx.Translate(canvasX, canvasY)
+	ctx.Scale(ctm.a/imgW, ctm.d/imgH)
+	ctx.DrawImage(0, 0, img, canvas.DPMM(1.0))
+	ctx.Pop()
+}
+
+// renderPath 渲染路径
+// 入参: ctx 画布上下文, obj 路径对象, pageH 页面高度, defaultFill 默认填充色, defaultStroke 默认描边色, defaultLW 默认线宽
+func (r *Renderer) renderPath(ctx *canvas.Context, obj PathObject, pageH float64, defaultFill, defaultStroke color.Color, defaultLW float64) {
+	ctx.Push()
+	bx, by := 0.0, 0.0
+	if obj.Boundary != "" {
+		if box, err := ParseBox(obj.Boundary); err == nil {
+			bx, by = box.X, box.Y
+		}
+	}
+	ctm := NewMatrix(obj.CTM)
+	fillColor, strokeColor := defaultFill, defaultStroke
+	if strokeColor == nil {
+		strokeColor = canvas.Black
+	}
+	lineWidth := defaultLW
+	if lineWidth == 0 {
+		lineWidth = 0.353
+	}
+	if obj.DrawParam != "" {
+		if dp := r.getDrawParam(obj.DrawParam, nil); dp != nil {
+			if dp.LineWidth > 0 {
+				lineWidth = dp.LineWidth
+			}
+			if dp.FillColor != nil {
+				fillColor = parseColor(dp.FillColor.Value)
+			}
+			if dp.StrokeColor != nil {
+				strokeColor = parseColor(dp.StrokeColor.Value)
+			}
+		}
+	}
+	if obj.LineWidth > 0 {
+		lineWidth = obj.LineWidth
+	}
+	if obj.FillColor != nil {
+		fillColor = parseColor(obj.FillColor.Value)
+	}
+	if obj.StrokeColor != nil {
+		strokeColor = parseColor(obj.StrokeColor.Value)
+	}
+	p := &canvas.Path{}
+	tokens := strings.Fields(obj.AbbreviatedData)
+	for i := 0; i < len(tokens); {
+		cmd := tokens[i]
+		i++
+		switch cmd {
+		case "M", "S":
+			if i+1 < len(tokens) {
+				x, _ := strconv.ParseFloat(tokens[i], 64)
+				y, _ := strconv.ParseFloat(tokens[i+1], 64)
+				tx, ty := ctm.Transform(x, y)
+				p.MoveTo(tx+bx, pageH-(ty+by))
+				i += 2
+			}
+		case "L":
+			if i+1 < len(tokens) {
+				x, _ := strconv.ParseFloat(tokens[i], 64)
+				y, _ := strconv.ParseFloat(tokens[i+1], 64)
+				tx, ty := ctm.Transform(x, y)
+				p.LineTo(tx+bx, pageH-(ty+by))
+				i += 2
+			}
+		case "B":
+			if i+5 < len(tokens) {
+				x1, _ := strconv.ParseFloat(tokens[i], 64)
+				y1, _ := strconv.ParseFloat(tokens[i+1], 64)
+				x2, _ := strconv.ParseFloat(tokens[i+2], 64)
+				y2, _ := strconv.ParseFloat(tokens[i+3], 64)
+				x3, _ := strconv.ParseFloat(tokens[i+4], 64)
+				y3, _ := strconv.ParseFloat(tokens[i+5], 64)
+				tx1, ty1 := ctm.Transform(x1, y1)
+				tx2, ty2 := ctm.Transform(x2, y2)
+				tx3, ty3 := ctm.Transform(x3, y3)
+				p.CubeTo(tx1+bx, pageH-(ty1+by), tx2+bx, pageH-(ty2+by), tx3+bx, pageH-(ty3+by))
+				i += 6
+			}
+		case "C":
+			p.Close()
+		}
+	}
+	if fillColor != nil {
+		ctx.SetFillColor(fillColor)
+		ctx.DrawPath(0, 0, p)
+	}
+	ctx.SetStrokeColor(strokeColor)
+	ctx.SetStrokeWidth(lineWidth)
+	ctx.DrawPath(0, 0, p.Stroke(lineWidth, canvas.RoundCap, canvas.RoundJoin, canvas.Tolerance))
+	ctx.Pop()
+}
+
+// renderText 渲染文本
+// 入参: ctx 画布上下文, obj 文本对象, pageH 页面高度, defaultFill 默认填充色, defaultStroke 默认描边色
+func (r *Renderer) renderText(ctx *canvas.Context, obj TextObject, pageH float64, defaultFill, defaultStroke color.Color) {
+	ctx.Push()
+	bx, by := 0.0, 0.0
+	if obj.Boundary != "" {
+		if box, err := ParseBox(obj.Boundary); err == nil {
+			bx, by = box.X, box.Y
+		}
+	}
+	ctm := NewMatrix(obj.CTM)
+	sizeMM := obj.Size
+	if sizeMM == 0 {
+		sizeMM = 3.5
+	}
+	if scale := ctm.YScale(); scale > 0 {
+		sizeMM *= scale
+	}
+	sizePt := sizeMM * 2.83465
+	textColor := defaultFill
+	if textColor == nil {
+		textColor = canvas.Black
+	}
+	if obj.DrawParam != "" {
+		if dp := r.getDrawParam(obj.DrawParam, nil); dp != nil && dp.FillColor != nil {
+			textColor = parseColor(dp.FillColor.Value)
+		}
+	}
+	if obj.FillColor != nil {
+		textColor = parseColor(obj.FillColor.Value)
+	}
+	fontStyle := canvas.FontRegular
+	if obj.Weight >= 700 || (obj.Weight == 0 && (strings.Contains(strings.ToLower(obj.Font), "bold"))) {
+		fontStyle |= canvas.FontBold
+	}
+	if obj.Italic {
+		fontStyle |= canvas.FontItalic
+	}
+	ff := r.loadFont(obj.Font)
+	face := ff.Face(sizePt, textColor, fontStyle, canvas.FontNormal)
+	for _, tc := range obj.TextCode {
+		runes := []rune(tc.Value)
+		dxs, dys := parseFloats(tc.DeltaX), parseFloats(tc.DeltaY)
+		cx, cy := tc.X, tc.Y
+		for i, run := range runes {
+			str := string(run)
+			if i > 0 {
+				if i-1 < len(dxs) {
+					cx += dxs[i-1]
+				} else {
+					cx += face.TextWidth(str)
+				}
+				if i-1 < len(dys) {
+					cy += dys[i-1]
+				}
+			}
+			tx, ty := ctm.Transform(cx, cy)
+			canvasX, canvasY := tx+bx, pageH-(ty+by)
+			text := canvas.NewTextLine(face, str, canvas.Left)
+			ctx.DrawText(canvasX, canvasY, text)
+			if strings.Contains(obj.Decoration, "Underline") {
+				uw := sizeMM * 0.05
+				if uw < 0.05 {
+					uw = 0.05
+				}
+				ctx.SetStrokeWidth(uw)
+				ctx.SetStrokeColor(textColor)
+				off := sizeMM * 0.1
+				ctx.MoveTo(canvasX, canvasY-off)
+				ctx.LineTo(canvasX+face.TextWidth(str), canvasY-off)
+				ctx.Stroke()
+			}
+		}
+	}
+	ctx.Pop()
+}
+
+// loadFont 加载字体
+// 入参: fontID 字体ID
+// 返回: *canvas.FontFamily 字体族
+func (r *Renderer) loadFont(fontID string) *canvas.FontFamily {
+	if ff, ok := r.FontMap[fontID]; ok {
+		return ff
+	}
+	defaultFont := r.fontFamily
+	of, ok := r.Reader.fontCache[fontID]
+	if !ok {
+		return defaultFont
+	}
+	ff := canvas.NewFontFamily(of.FontName)
+	if of.FontFile != "" {
+		if fontData, err := r.Reader.ResData(of.FontFile); err == nil {
+			if err := ff.LoadFont(fontData, 0, canvas.FontRegular); err == nil {
+				r.FontMap[fontID] = ff
+				return ff
+			}
+		}
+	}
+	for _, dir := range r.fontDirs {
+		matches, _ := filepath.Glob(filepath.Join(dir, of.FontName+"*"))
+		for _, m := range matches {
+			ext := strings.ToLower(filepath.Ext(m))
+			if ext == ".ttf" || ext == ".otf" || ext == ".ttc" {
+				if err := ff.LoadFontFile(m, canvas.FontRegular); err == nil {
+					r.FontMap[fontID] = ff
+					return ff
+				}
+			}
+		}
+	}
+	for _, fsys := range r.fontFS {
+		if matches, err := fs.Glob(fsys, of.FontName+"*"); err == nil {
+			for _, m := range matches {
+				resData, err := fs.ReadFile(fsys, m)
+				if err == nil {
+					if err := ff.LoadFont(resData, 0, canvas.FontRegular); err == nil {
+						r.FontMap[fontID] = ff
+						return ff
+					}
+				}
+			}
+		}
+	}
+	names := []string{of.FamilyName, of.FontName}
+	aliases := map[string]string{
+		"simhei":          "SimHei",
+		"黑体":              "SimHei",
+		"microsoft yahei": "Microsoft YaHei",
+		"微软雅黑":            "Microsoft YaHei",
+		"simsun":          "SimSun",
+		"宋体":              "SimSun",
+		"kaiti":           "KaiTi",
+		"楷体":              "KaiTi",
+		"fangsong":        "FangSong",
+		"仿宋":              "FangSong",
+		"arial":           "Arial",
+		"segoe ui":        "Segoe UI",
+		"times new roman": "Times New Roman",
+	}
+	for _, name := range names {
+		if name == "" {
+			continue
+		}
+		targetName := name
+		lower := strings.ToLower(name)
+		if mapped, ok := aliases[lower]; ok {
+			targetName = mapped
+		} else {
+			for k, v := range aliases {
+				if strings.Contains(lower, k) {
+					targetName = v
+					break
+				}
+			}
+		}
+		if err := ff.LoadSystemFont(targetName, canvas.FontRegular); err == nil {
+			r.FontMap[fontID] = ff
+			return ff
+		}
+		if targetName != name {
+			if err := ff.LoadSystemFont(name, canvas.FontRegular); err == nil {
+				r.FontMap[fontID] = ff
+				return ff
+			}
+		}
+	}
+	return defaultFont
+}