mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-30 01:27:26 +08:00
201 lines
6.9 KiB
Go
201 lines
6.9 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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"bytes"
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"context"
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"crypto/sha256"
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"fmt"
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"io"
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)
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// svgNamespace 表示SVG预览文档命名空间
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const svgNamespace = "http://www.w3.org/2000/svg"
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// SVGFont SVG引用的字体资源，Name为CSS字体族标识，Data为只读字体数据
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type SVGFont struct {
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Name string
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Weight int
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Style string
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Data []byte
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}
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// SVGImage SVG引用的图片资源，Name为图片地址，Data为只读图片数据
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type SVGImage struct {
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Name string
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MIME string
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Data []byte
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}
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// SVGResources SVG引用的字体和图片资源
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type SVGResources struct {
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Fonts []SVGFont
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Images []SVGImage
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}
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// PreviewOptions 指定页面显示方式，光栅预览不提供SVG对象分组
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type PreviewOptions struct {
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Raster bool
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Objects bool
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// KnownResources 标识调用方仍持有的资源，返回引用但不重复返回数据
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KnownResources map[string]bool
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}
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// RenderToSVGWithFonts 渲染为SVG并返回页面引用的字体资源，不在SVG中嵌入字体
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// 入参: page 页面内容, writer 输出流
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// 返回: []SVGFont 字体资源，可按Name复用并按Weight、Style注册，error 错误信息
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func (r *Renderer) RenderToSVGWithFonts(page *PageContent, writer io.Writer) ([]SVGFont, error) {
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resources, err := r.renderSVG(page, writer, SVGExternalFonts)
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return resources.Fonts, err
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}
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// RenderToSVGWithResources 渲染为SVG并分离字体和图片，调用方需注册字体并将图片Name映射为可访问地址
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// 入参: page 页面内容, writer 输出流
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// 返回: SVGResources 可跨页面复用的资源, error 错误信息
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func (r *Renderer) RenderToSVGWithResources(page *PageContent, writer io.Writer) (SVGResources, error) {
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return r.renderSVG(page, writer, SVGExternalResources)
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}
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// RenderToSVGWithObjects 渲染SVG并为页面对象和注解添加data-ofd-object分组，注解标识使用annotation:前缀
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// 入参: page 页面内容, writer 输出流
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// 返回: SVGResources 字体和图片资源, error 错误信息
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func (r *Renderer) RenderToSVGWithObjects(page *PageContent, writer io.Writer) (SVGResources, error) {
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return r.renderSVG(page, writer, SVGObjects)
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}
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// renderSVG 将SVG输出及对象分组交给指定后端
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// 入参: page 页面内容, writer 输出流, mode 资源封装方式
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// 返回: SVGResources 字体和图片资源, error 渲染、写入或取消错误
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func (r *Renderer) renderSVG(page *PageContent, writer io.Writer, mode SVGMode) (SVGResources, error) {
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if err := r.Compression.Validate(); err != nil {
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return SVGResources{}, err
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}
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if r.backends.SVG == nil {
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return SVGResources{}, fmt.Errorf("svg: %w", ErrBackendUnavailable)
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}
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var written int64
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writer = convertWriter{ctx: r.outputContext(), writer: writer, count: &written}
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return r.backends.SVG.RenderSVG(r, page, writer, mode)
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}
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// RenderPreview 生成统一SVG容器及独立资源，原生程序与WebUI使用相同绘制入口
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// 入参: page 页面内容, writer 输出流, options 显示方式
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// 返回: SVGResources 需由调用方映射地址的资源, error 错误信息
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func (r *Renderer) RenderPreview(page *PageContent, writer io.Writer, options PreviewOptions) (resources SVGResources, err error) {
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defer func() {
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for i := range resources.Fonts {
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if options.KnownResources[resources.Fonts[i].Name] {
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resources.Fonts[i].Data = nil
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}
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}
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for i := range resources.Images {
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if options.KnownResources[resources.Images[i].Name] {
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resources.Images[i].Data = nil
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}
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}
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}()
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if !options.Raster {
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if options.Objects {
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return r.RenderToSVGWithObjects(page, writer)
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}
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return r.RenderToSVGWithResources(page, writer)
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}
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if options.Objects {
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return SVGResources{}, fmt.Errorf("raster preview does not provide SVG object groups")
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}
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box, err := r.GetPageBox(page)
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if err != nil {
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return SVGResources{}, err
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}
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var pixels bytes.Buffer
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if err := r.RenderToPNG(page, &pixels); err != nil {
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return SVGResources{}, err
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}
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name := fmt.Sprintf("ofdgo-image-%x", sha256.Sum256(pixels.Bytes()))
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_, err = fmt.Fprintf(writer, `<svg xmlns="`+svgNamespace+`" xmlns:xlink="`+XLinkNamespace+`" width="%gmm" height="%gmm" viewBox="0 0 %g %g"><image width="%g" height="%g" preserveAspectRatio="none" xlink:href="%s"/></svg>`, box.W, box.H, box.W, box.H, box.W, box.H, name)
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if err != nil {
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return SVGResources{}, err
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}
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return SVGResources{Images: []SVGImage{{Name: name, MIME: "image/png", Data: pixels.Bytes()}}}, nil
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}
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// RenderFontPreview 将指定字体的前32个可见字形绘制为独立SVG，不依赖字符映射或浏览器字体
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// 排除缺字字形，外部字体须精确匹配，不修改原始资源或使用无关回退字体
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// 入参: ctx 取消上下文, id 字体资源标识, writer 输出流
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// 返回: error 字体、轮廓、取消或写入错误
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func (r *Renderer) RenderFontPreview(ctx context.Context, id string, writer io.Writer) error {
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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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resolved, err := view.ResolveFont(id, true)
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if err != nil {
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return err
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}
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font := &PreparedFont{ResolvedFont: resolved}
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if definition := view.Reader.fontDefinition(id); definition != nil && definition.FontFile != "" {
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font, err = view.PrepareFont(id)
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if err != nil {
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return err
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}
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}
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metrics, err := view.preparedMetrics(font)
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if err != nil {
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return err
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}
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outlines, ok := metrics.(FontOutlines)
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if !ok {
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return fmt.Errorf("font outlines: %w", ErrBackendUnavailable)
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}
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var paths bytes.Buffer
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count := 0
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for glyph := uint16(1); glyph < metrics.NumGlyphs() && count < 32; glyph++ {
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if err := ctx.Err(); err != nil {
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return err
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}
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outline, err := outlines.GlyphOutline(glyph, 24)
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if err != nil {
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return err
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}
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box, err := outline.Bounds()
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if err != nil {
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return err
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}
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if box.W <= 0 || box.H <= 0 {
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continue
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}
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path, err := outline.SVG()
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if err != nil {
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return err
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}
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scale := min(1.0, 28/box.W, 32/box.H)
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x := float64(count%8)*36 + (36-box.W*scale)/2 - box.X*scale
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y := float64(count/8)*40 + (40-box.H*scale)/2 - box.Y*scale
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fmt.Fprintf(&paths, `<path transform="translate(%g %g) scale(%g)" d="%s"/>`, x, y, scale, path)
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count++
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}
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if err := ctx.Err(); err != nil {
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return err
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}
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if count == 0 {
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return fmt.Errorf("font has no visible glyphs")
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}
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width, height := min(count, 8)*36, (count+7)/8*40
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_, err = fmt.Fprintf(writer, `<svg xmlns="`+svgNamespace+`" width="%d" height="%d" viewBox="0 0 %d %d">%s</svg>`, width, height, width, height, paths.Bytes())
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return err
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}
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