feat: add text-to-image conversion utility with Markdown and HTML support

go.mod

@@ -45,6 +45,7 @@ require (
 	github.com/goccy/go-json v0.10.2 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
+	github.com/gomarkdown/markdown v0.0.0-20250207164621-7a1f277a159e // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/klauspost/cpuid/v2 v2.2.7 // indirect
@@ -62,6 +63,7 @@ require (
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.2.12 // indirect
+	github.com/yuin/goldmark v1.7.8 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.56.0 // indirect
 	go.opentelemetry.io/otel v1.31.0 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.31.0 // indirect

go.sum

@@ -73,6 +73,8 @@ github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
+github.com/gomarkdown/markdown v0.0.0-20250207164621-7a1f277a159e h1:ESHlT0RVZphh4JGBz49I5R6nTdC8Qyc08vU25GQHzzQ=
+github.com/gomarkdown/markdown v0.0.0-20250207164621-7a1f277a159e/go.mod h1:JDGcbDT52eL4fju3sZ4TeHGsQwhG9nbDV21aMyhwPoA=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
@@ -163,6 +165,8 @@ github.com/ugorji/go/codec v1.2.12 h1:9LC83zGrHhuUA9l16C9AHXAqEV/2wBQ4nkvumAE65E
 github.com/ugorji/go/codec v1.2.12/go.mod h1:UNopzCgEMSXjBc6AOMqYvWC1ktqTAfzJZUZgYf6w6lg=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+github.com/yuin/goldmark v1.7.8 h1:iERMLn0/QJeHFhxSt3p6PeN9mGnvIKSpG9YYorDMnic=
+github.com/yuin/goldmark v1.7.8/go.mod h1:uzxRWxtg69N339t3louHJ7+O03ezfj6PlliRlaOzY1E=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.56.0 h1:UP6IpuHFkUgOQL9FFQFrZ+5LiwhhYRbi7VZSIx6Nj5s=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.56.0/go.mod h1:qxuZLtbq5QDtdeSHsS7bcf6EH6uO6jUAgk764zd3rhM=
 go.opentelemetry.io/otel v1.31.0 h1:NsJcKPIW0D0H3NgzPDHmo0WW6SptzPdqg/L1zsIm2hY=

util/text_to_pic.go

@@ -0,0 +1,199 @@
+package util
+
+import (
+	"bytes"
+	"image"
+	"image/color"
+	"image/jpeg"
+	"image/png"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/fogleman/gg"
+	"github.com/yuin/goldmark"
+	"golang.org/x/net/html"
+)
+
+const (
+	defaultWidth   = 800
+	defaultMargin  = 20
+	lineHeight     = 1.5
+	fontSize       = 14
+	maxImageWidth  = 600
+	maxImageHeight = 400
+)
+
+type ContentBlock struct {
+	Type      string      // "text" or "image"
+	Content   string      // text content or image path
+	ImgWidth  float64     // image width after resize
+	ImgHeight float64     // image height after resize
+	Image     image.Image // loaded image
+}
+
+// TextToPicture 将文本转换为图片
+func TextToPicture(text string, isMarkdown bool) (image.Image, error) {
+	var htmlContent string
+	if isMarkdown {
+		// 将Markdown转换为HTML
+		md := goldmark.New()
+		var buf bytes.Buffer
+		if err := md.Convert([]byte(text), &buf); err != nil {
+			return nil, err
+		}
+		htmlContent = buf.String()
+	} else {
+		htmlContent = text
+	}
+
+	// 解析HTML并提取内容块
+	doc, err := html.Parse(strings.NewReader(htmlContent))
+	if err != nil {
+		return nil, err
+	}
+
+	var blocks []ContentBlock
+	var extractContent func(*html.Node)
+	extractContent = func(n *html.Node) {
+		if n.Type == html.TextNode {
+			text := strings.TrimSpace(n.Data)
+			if text != "" {
+				blocks = append(blocks, ContentBlock{
+					Type:    "text",
+					Content: text,
+				})
+			}
+		} else if n.Type == html.ElementNode && n.Data == "img" {
+			// 处理图片节点
+			var src string
+			for _, attr := range n.Attr {
+				if attr.Key == "src" {
+					src = attr.Val
+					break
+				}
+			}
+			if src != "" && !strings.HasPrefix(src, "http") {
+				// 处理本地图片
+				img, w, h, err := loadAndResizeImage(src)
+				if err == nil {
+					blocks = append(blocks, ContentBlock{
+						Type:      "image",
+						Content:   src,
+						Image:     img,
+						ImgWidth:  w,
+						ImgHeight: h,
+					})
+				}
+			}
+		}
+		for c := n.FirstChild; c != nil; c = c.NextSibling {
+			extractContent(c)
+		}
+	}
+	extractContent(doc)
+
+	// 计算总高度
+	totalHeight := calculateTotalHeight(blocks)
+
+	// 创建图片上下文
+	dc := gg.NewContext(defaultWidth, totalHeight)
+	dc.SetRGB(1, 1, 1) // 设置白色背景
+	dc.Clear()
+
+	// 设置字体和颜色
+	if err := dc.LoadFontFace("./resource/fonts/SourceHanSansCN-Regular.otf", fontSize); err != nil {
+		return nil, err
+	}
+	dc.SetColor(color.Black)
+
+	// 绘制内容
+	y := float64(defaultMargin)
+	for _, block := range blocks {
+		if block.Type == "text" {
+			wrapped := dc.WordWrap(block.Content, float64(defaultWidth-2*defaultMargin))
+			for _, wrappedLine := range wrapped {
+				dc.DrawString(wrappedLine, float64(defaultMargin), y+fontSize)
+				y += fontSize * lineHeight
+			}
+			y += fontSize // 段落间额外间距
+		} else if block.Type == "image" {
+			// 居中绘制图片
+			x := (float64(defaultWidth) - block.ImgWidth) / 2
+			dc.DrawImage(block.Image, int(x), int(y))
+			y += block.ImgHeight + float64(defaultMargin) // 图片后添加间距
+		}
+	}
+
+	return dc.Image(), nil
+}
+
+// loadAndResizeImage 加载并调整图片大小
+func loadAndResizeImage(path string) (image.Image, float64, float64, error) {
+	// 确保路径是绝对路径
+	if !filepath.IsAbs(path) {
+		path = filepath.Join(".", path)
+	}
+
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	defer file.Close()
+
+	// 解码图片
+	var img image.Image
+	if strings.HasSuffix(strings.ToLower(path), ".png") {
+		img, err = png.Decode(file)
+	} else {
+		img, err = jpeg.Decode(file)
+	}
+	if err != nil {
+		return nil, 0, 0, err
+	}
+
+	// 计算调整后的尺寸
+	bounds := img.Bounds()
+	origWidth := float64(bounds.Dx())
+	origHeight := float64(bounds.Dy())
+
+	var newWidth, newHeight float64
+	if origWidth > maxImageWidth {
+		ratio := maxImageWidth / origWidth
+		newWidth = maxImageWidth
+		newHeight = origHeight * ratio
+	} else {
+		newWidth = origWidth
+		newHeight = origHeight
+	}
+
+	if newHeight > maxImageHeight {
+		ratio := maxImageHeight / newHeight
+		newHeight = maxImageHeight
+		newWidth = newWidth * ratio
+	}
+
+	// 创建新的图片上下文并调整大小
+	dc := gg.NewContext(int(newWidth), int(newHeight))
+	dc.DrawImage(img, 0, 0)
+
+	return dc.Image(), newWidth, newHeight, nil
+}
+
+// calculateTotalHeight 计算总高度
+func calculateTotalHeight(blocks []ContentBlock) int {
+	var totalHeight float64 = float64(2 * defaultMargin) // 上下边距
+
+	for _, block := range blocks {
+		if block.Type == "text" {
+			// 估算文本高度
+			estimatedLines := (len(block.Content)*fontSize)/(defaultWidth-2*defaultMargin) + 1
+			totalHeight += float64(estimatedLines) * fontSize * lineHeight
+			totalHeight += fontSize // 段落间距
+		} else if block.Type == "image" {
+			totalHeight += block.ImgHeight + float64(defaultMargin) // 图片高度加间距
+		}
+	}
+
+	return int(totalHeight)
+}