feat(归并文件): 归并根包文件，保持接口不变

ofdgo_render_svg.go

@@ -15,10 +15,16 @@
 package ofdgo
 
 import (
+	"bytes"
+	"context"
+	"crypto/sha256"
 	"fmt"
 	"io"
 )
 
+// svgNamespace 表示SVG预览文档命名空间
+const svgNamespace = "http://www.w3.org/2000/svg"
+
 // 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
 type SVGFont struct {
 	Name   string
@@ -40,6 +46,12 @@ type SVGResources struct {
 	Images []SVGImage
 }
 
+// PreviewOptions 指定页面显示方式，光栅预览不提供SVG对象分组
+type PreviewOptions struct {
+	Raster  bool
+	Objects bool
+}
+
 // 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
 // 入参: page 页面内容, writer 输出流
 // 返回: []SVGFont 字体资源，可按Name复用并按Weight、Style注册，error 错误信息
@@ -76,3 +88,99 @@ func (r *Renderer) renderSVG(page *PageContent, writer io.Writer, mode SVGMode)
 	writer = convertWriter{ctx: r.outputContext(), writer: writer, count: &written}
 	return r.backends.SVG.RenderSVG(r, page, writer, mode)
 }
+
+// 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
+// 入参: page 页面内容, writer 输出流, options 显示方式
+// 返回: SVGResources 需由调用方映射地址的资源, error 错误信息
+func (r *Renderer) RenderPreview(page *PageContent, writer io.Writer, options PreviewOptions) (SVGResources, error) {
+	if !options.Raster {
+		if options.Objects {
+			return r.RenderToSVGWithObjects(page, writer)
+		}
+		return r.RenderToSVGWithResources(page, writer)
+	}
+	if options.Objects {
+		return SVGResources{}, fmt.Errorf("raster preview does not provide SVG object groups")
+	}
+	box, err := r.GetPageBox(page)
+	if err != nil {
+		return SVGResources{}, err
+	}
+	var pixels bytes.Buffer
+	if err := r.RenderToPNG(page, &pixels); err != nil {
+		return SVGResources{}, err
+	}
+	name := fmt.Sprintf("ofdgo-image-%x", sha256.Sum256(pixels.Bytes()))
+	_, 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)
+	if err != nil {
+		return SVGResources{}, err
+	}
+	return SVGResources{Images: []SVGImage{{Name: name, MIME: "image/png", Data: pixels.Bytes()}}}, nil
+}
+
+// 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
+// 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
+// 入参: ctx 取消上下文, id 字体资源标识, writer 输出流
+// 返回: error 字体、轮廓、取消或写入错误
+func (r *Renderer) RenderFontPreview(ctx context.Context, id string, writer io.Writer) error {
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	view := *r
+	view.pageContext = ctx
+	resolved, err := view.ResolveFont(id, true)
+	if err != nil {
+		return err
+	}
+	font := &PreparedFont{ResolvedFont: resolved}
+	if definition := view.Reader.fontDefinition(id); definition != nil && definition.FontFile != "" {
+		font, err = view.PrepareFont(id)
+		if err != nil {
+			return err
+		}
+	}
+	metrics, err := view.preparedMetrics(font)
+	if err != nil {
+		return err
+	}
+	outlines, ok := metrics.(FontOutlines)
+	if !ok {
+		return fmt.Errorf("font outlines: %w", ErrBackendUnavailable)
+	}
+	var paths bytes.Buffer
+	count := 0
+	for glyph := uint16(1); glyph < metrics.NumGlyphs() && count < 32; glyph++ {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		outline, err := outlines.GlyphOutline(glyph, 24)
+		if err != nil {
+			return err
+		}
+		box, err := outline.Bounds()
+		if err != nil {
+			return err
+		}
+		if box.W <= 0 || box.H <= 0 {
+			continue
+		}
+		path, err := outline.SVG()
+		if err != nil {
+			return err
+		}
+		scale := min(1.0, 28/box.W, 32/box.H)
+		x := float64(count%8)*36 + (36-box.W*scale)/2 - box.X*scale
+		y := float64(count/8)*40 + (40-box.H*scale)/2 - box.Y*scale
+		fmt.Fprintf(&paths, `<path transform="translate(%g %g) scale(%g)" d="%s"/>`, x, y, scale, path)
+		count++
+	}
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	if count == 0 {
+		return fmt.Errorf("font has no visible glyphs")
+	}
+	width, height := min(count, 8)*36, (count+7)/8*40
+	_, err = fmt.Fprintf(writer, `<svg xmlns="`+svgNamespace+`" width="%d" height="%d" viewBox="0 0 %d %d">%s</svg>`, width, height, width, height, paths.Bytes())
+	return err
+}