update at 2026-02-08 18:28:39

miniprogram/workers/svg-generator/svg-builder.js

@@ -0,0 +1,188 @@
+const { wrapTextByChars } = require('./text-layout')
+
+function formatNumber(value) {
+  const text = Number(value).toFixed(2).replace(/\.?0+$/, '')
+  return text || '0'
+}
+
+function getGlyphPath(glyph) {
+  const path = glyph && glyph.path
+  if (!path || !Array.isArray(path.commands) || !path.commands.length) {
+    return ''
+  }
+
+  const commands = []
+  for (const cmd of path.commands) {
+    switch (cmd.type) {
+      case 'M':
+        commands.push(`M${formatNumber(cmd.x)} ${formatNumber(cmd.y)}`)
+        break
+      case 'L':
+        commands.push(`L${formatNumber(cmd.x)} ${formatNumber(cmd.y)}`)
+        break
+      case 'Q':
+        commands.push(`Q${formatNumber(cmd.x1)} ${formatNumber(cmd.y1)} ${formatNumber(cmd.x)} ${formatNumber(cmd.y)}`)
+        break
+      case 'C':
+        commands.push(`C${formatNumber(cmd.x1)} ${formatNumber(cmd.y1)} ${formatNumber(cmd.x2)} ${formatNumber(cmd.y2)} ${formatNumber(cmd.x)} ${formatNumber(cmd.y)}`)
+        break
+      case 'Z':
+        commands.push('Z')
+        break
+      default:
+        break
+    }
+  }
+
+  return commands.join(' ')
+}
+
+function getGlyphBounds(glyph) {
+  const path = glyph && glyph.path
+  if (!path || !Array.isArray(path.commands) || !path.commands.length) {
+    return null
+  }
+
+  let xMin = Infinity
+  let yMin = Infinity
+  let xMax = -Infinity
+  let yMax = -Infinity
+
+  for (const cmd of path.commands) {
+    if (typeof cmd.x === 'number') {
+      xMin = Math.min(xMin, cmd.x)
+      xMax = Math.max(xMax, cmd.x)
+      yMin = Math.min(yMin, cmd.y)
+      yMax = Math.max(yMax, cmd.y)
+    }
+    if (typeof cmd.x1 === 'number') {
+      xMin = Math.min(xMin, cmd.x1)
+      xMax = Math.max(xMax, cmd.x1)
+      yMin = Math.min(yMin, cmd.y1)
+      yMax = Math.max(yMax, cmd.y1)
+    }
+    if (typeof cmd.x2 === 'number') {
+      xMin = Math.min(xMin, cmd.x2)
+      xMax = Math.max(xMax, cmd.x2)
+      yMin = Math.min(yMin, cmd.y2)
+      yMax = Math.max(yMax, cmd.y2)
+    }
+  }
+
+  if (xMin === Infinity) {
+    return null
+  }
+
+  return { xMin, yMin, xMax, yMax }
+}
+
+function generateSvgFromFont(options) {
+  const {
+    text,
+    font,
+    fontSize = 100,
+    fillColor = '#000000',
+    letterSpacing = 0,
+    maxCharsPerLine,
+  } = options
+
+  if (!text || !String(text).trim()) {
+    throw new Error('文本内容不能为空')
+  }
+
+  const normalizedText = wrapTextByChars(text, maxCharsPerLine)
+
+  const scale = fontSize / font.unitsPerEm
+  const letterSpacingRaw = letterSpacing * font.unitsPerEm
+
+  const glyphRuns = []
+  let minX = null
+  let minY = null
+  let maxX = null
+  let maxY = null
+  let maxLineAdvance = 0
+
+  const ascender = Number.isFinite(font.ascender) ? font.ascender : font.unitsPerEm * 0.8
+  const descender = Number.isFinite(font.descender) ? font.descender : -font.unitsPerEm * 0.2
+  const lineAdvance = Math.max(font.unitsPerEm * 1.2, ascender - descender)
+  const lines = normalizedText.split('\n')
+
+  for (let lineIndex = 0; lineIndex < lines.length; lineIndex += 1) {
+    const line = lines[lineIndex] || ''
+    const yPos = -lineIndex * lineAdvance
+    let xPos = 0
+
+    for (const char of Array.from(line)) {
+      const glyph = font.charToGlyph(char)
+      glyphRuns.push({ glyph, xPos, yPos })
+
+      const bounds = getGlyphBounds(glyph)
+      if (bounds) {
+        const adjustedXMin = bounds.xMin + xPos
+        const adjustedYMin = bounds.yMin + yPos
+        const adjustedXMax = bounds.xMax + xPos
+        const adjustedYMax = bounds.yMax + yPos
+
+        minX = minX === null ? adjustedXMin : Math.min(minX, adjustedXMin)
+        minY = minY === null ? adjustedYMin : Math.min(minY, adjustedYMin)
+        maxX = maxX === null ? adjustedXMax : Math.max(maxX, adjustedXMax)
+        maxY = maxY === null ? adjustedYMax : Math.max(maxY, adjustedYMax)
+      }
+
+      xPos += (glyph.advanceWidth || 0) + letterSpacingRaw
+    }
+
+    maxLineAdvance = Math.max(maxLineAdvance, xPos)
+  }
+
+  if (minX === null || maxX === null) {
+    minX = 0
+    maxX = maxLineAdvance
+  }
+
+  if (minX === null || minY === null || maxX === null || maxY === null) {
+    throw new Error('未生成有效字形轮廓')
+  }
+
+  const width = (maxX - minX) * scale
+  const height = (maxY - minY) * scale
+
+  if (width <= 0 || height <= 0) {
+    throw new Error('计算得到的 SVG 尺寸无效')
+  }
+
+  const paths = []
+  for (const run of glyphRuns) {
+    const d = getGlyphPath(run.glyph)
+    if (!d) {
+      continue
+    }
+    const transform = `translate(${formatNumber(run.xPos)} ${formatNumber(run.yPos)})`
+    paths.push(`  <path d=\"${d}\" transform=\"${transform}\"/>`)
+  }
+
+  if (!paths.length) {
+    throw new Error('未生成任何路径')
+  }
+
+  const viewBox = `${formatNumber(minX)} 0 ${formatNumber(maxX - minX)} ${formatNumber(maxY - minY)}`
+  const groupTransform = `translate(0 ${formatNumber(maxY)}) scale(1 -1)`
+
+  const svg = `<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\"?>\n<svg xmlns=\"http://www.w3.org/2000/svg\" viewBox=\"${viewBox}\" width=\"${formatNumber(width)}\" height=\"${formatNumber(height)}\" preserveAspectRatio=\"xMidYMid meet\">\n  <g transform=\"${groupTransform}\" fill=\"${fillColor}\" stroke=\"none\">\n${paths.join('\n')}\n  </g>\n</svg>`
+
+  const fontName =
+    (font.names && font.names.fontFamily && (font.names.fontFamily.en || font.names.fontFamily.zh)) ||
+    (font.names && font.names.fullName && (font.names.fullName.en || font.names.fullName.zh)) ||
+    'Unknown'
+
+  return {
+    svg,
+    width,
+    height,
+    fontName,
+  }
+}
+
+module.exports = {
+  generateSvgFromFont,
+}