fix(extension): improve title display and mindmap export

BillNote_extension/src/components/MindMap.vue

@@ -1,32 +1,181 @@
 <script setup lang="ts">
-import { onMounted, ref, watch } from 'vue'
+import { nextTick, onMounted, onUnmounted, ref, watch } from 'vue'
 import { Transformer } from 'markmap-lib'
 import { Markmap } from 'markmap-view'
 import { absolutizeMarkdownImages, stripSourceLink } from '~/logic/api'
 
 const props = defineProps<{ markdown: string }>()
 
+const wrapRef = ref<HTMLDivElement | null>(null)
 const svgRef = ref<SVGSVGElement | null>(null)
 let mm: Markmap | null = null
+let resizeObserver: ResizeObserver | null = null
 const transformer = new Transformer()
+const MIN_EXPORT_FONT_PX = 256
+const MIN_EXPORT_WIDTH = 12800
+const MAX_EXPORT_SCALE = 24
+const MAX_CANVAS_SIDE = 32767
 
-function render() {
-  if (!svgRef.value)
-    return
-  const md = absolutizeMarkdownImages(stripSourceLink(props.markdown || ''))
-  const { root } = transformer.transform(md)
-  if (!mm)
-    mm = Markmap.create(svgRef.value, undefined, root)
-  else
-    mm.setData(root).then(() => mm?.fit())
+function canvasToBlob(canvas: HTMLCanvasElement): Promise<Blob> {
+  return new Promise((resolve, reject) => {
+    canvas.toBlob((blob) => {
+      if (blob)
+        resolve(blob)
+      else
+        reject(new Error('导出思维导图图片失败'))
+    }, 'image/png')
+  })
 }
 
-onMounted(render)
+function createSvgElement<K extends keyof SVGElementTagNameMap>(tag: K): SVGElementTagNameMap[K] {
+  return document.createElementNS('http://www.w3.org/2000/svg', tag)
+}
+
+function sanitizeSvgForCanvas(svg: SVGSVGElement): SVGSVGElement {
+  const cloned = svg.cloneNode(true) as SVGSVGElement
+
+  cloned.querySelectorAll('image').forEach(el => el.remove())
+  cloned.querySelectorAll('foreignObject').forEach((foreignObject) => {
+    const textContent = foreignObject.textContent?.replace(/\s+/g, ' ').trim()
+    if (!textContent) {
+      foreignObject.remove()
+      return
+    }
+
+    const x = Number(foreignObject.getAttribute('x') || 0)
+    const y = Number(foreignObject.getAttribute('y') || 0)
+    const height = Number(foreignObject.getAttribute('height') || 20)
+    const text = createSvgElement('text')
+    text.setAttribute('x', String(x))
+    text.setAttribute('y', String(y + height / 2))
+    text.setAttribute('dominant-baseline', 'middle')
+    text.setAttribute('font-size', '14')
+    text.setAttribute('font-family', 'Arial, "Microsoft YaHei", sans-serif')
+    text.setAttribute('fill', '#333')
+    text.textContent = textContent
+    foreignObject.replaceWith(text)
+  })
+
+  return cloned
+}
+
+function getExportFontSize(svg: SVGSVGElement): number {
+  const text = svg.querySelector('text, foreignObject')
+  if (!text)
+    return 14
+
+  const fontSize = Number.parseFloat(getComputedStyle(text).fontSize || '')
+  if (Number.isFinite(fontSize) && fontSize > 0)
+    return fontSize
+
+  const attrSize = Number.parseFloat(text.getAttribute('font-size') || '')
+  return Number.isFinite(attrSize) && attrSize > 0 ? attrSize : 14
+}
+
+function stripMindmapNoise(md: string): string {
+  return absolutizeMarkdownImages(stripSourceLink(md || ''))
+    // 笔记里的截图/封面图片在思维导图中会被当作超大 SVG foreignObject，
+    // 容易把导图挤成截图里那种“只剩半框/一条竖线”的效果。导图只保留文字层级。
+    .replace(/!\[[^\]]*\]\([^)]*\)/g, '')
+    .replace(/<img\b[^>]*>/gi, '')
+}
+
+async function fit() {
+  await nextTick()
+  requestAnimationFrame(() => mm?.fit())
+}
+
+async function render() {
+  if (!svgRef.value)
+    return
+  const { root } = transformer.transform(stripMindmapNoise(props.markdown))
+  if (!mm)
+    mm = Markmap.create(svgRef.value, { autoFit: true }, root)
+  else
+    await mm.setData(root)
+  await fit()
+}
+
+async function toPngBlob(): Promise<Blob> {
+  await fit()
+  await nextTick()
+  if (!svgRef.value)
+    throw new Error('思维导图尚未渲染完成')
+
+  const svg = svgRef.value
+  const bbox = svg.getBBox()
+  const padding = 48
+  const x = Math.floor(bbox.x - padding)
+  const y = Math.floor(bbox.y - padding)
+  const width = Math.max(Math.ceil(bbox.width + padding * 2), 1)
+  const height = Math.max(Math.ceil(bbox.height + padding * 2), 1)
+  const cloned = sanitizeSvgForCanvas(svg)
+
+  cloned.setAttribute('xmlns', 'http://www.w3.org/2000/svg')
+  cloned.setAttribute('width', String(width))
+  cloned.setAttribute('height', String(height))
+  cloned.setAttribute('viewBox', `${x} ${y} ${width} ${height}`)
+  cloned.insertAdjacentHTML('afterbegin', `<rect width="100%" height="100%" fill="#fff"/>`)
+
+  const svgText = new XMLSerializer().serializeToString(cloned)
+  const url = URL.createObjectURL(new Blob([svgText], { type: 'image/svg+xml;charset=utf-8' }))
+
+  try {
+    const img = new Image()
+    img.decoding = 'async'
+    img.src = url
+    await img.decode()
+
+    // 不写死某个导出宽度：按导图内容和文字字号动态反推 PNG 倍率。
+    // 目标是让导出的正文至少有 MIN_EXPORT_FONT_PX 像素高，小图自动放大，
+    // 大图则按内容尺寸导出；同时限制最大边长，避免复杂导图撑爆内存。
+    const fontScale = MIN_EXPORT_FONT_PX / getExportFontSize(svg)
+    const widthScale = MIN_EXPORT_WIDTH / width
+    const rawScale = Math.max(window.devicePixelRatio || 1, fontScale, widthScale)
+    const sideLimitScale = Math.min(MAX_CANVAS_SIDE / width, MAX_CANVAS_SIDE / height)
+    const scale = Math.max(1, Math.min(rawScale, MAX_EXPORT_SCALE, sideLimitScale))
+    const canvas = document.createElement('canvas')
+    canvas.width = Math.ceil(width * scale)
+    canvas.height = Math.ceil(height * scale)
+    const ctx = canvas.getContext('2d')
+    if (!ctx)
+      throw new Error('当前浏览器不支持 Canvas 导出')
+    ctx.fillStyle = '#fff'
+    ctx.fillRect(0, 0, canvas.width, canvas.height)
+    ctx.scale(scale, scale)
+    ctx.drawImage(img, 0, 0, width, height)
+    return await canvasToBlob(canvas)
+  }
+  finally {
+    URL.revokeObjectURL(url)
+  }
+}
+
+defineExpose({
+  toPngBlob,
+})
+
+onMounted(() => {
+  render()
+  if (wrapRef.value) {
+    resizeObserver = new ResizeObserver(() => fit())
+    resizeObserver.observe(wrapRef.value)
+  }
+})
+
+onUnmounted(() => {
+  resizeObserver?.disconnect()
+  resizeObserver = null
+  mm?.destroy()
+  mm = null
+})
+
 watch(() => props.markdown, render)
+
 </script>
 
 <template>
-  <div class="w-full h-full bg-white rounded border overflow-hidden">
-    <svg ref="svgRef" class="w-full h-full" />
+  <div ref="wrapRef" class="w-full h-full min-h-[360px] bg-white rounded border overflow-hidden">
+    <svg ref="svgRef" class="w-full h-full min-h-[360px]" />
   </div>
 </template>