fix: #2836 fix formula first render (#2860)

* fix: #2836 fix formula first render

* Revert "refresh svg by innerHTML"

* add NS to vNode before path

* improve readability

src/muya/lib/parser/render/index.js

@@ -1,7 +1,7 @@
 import loadRenderer from '../../renderers'
 import { CLASS_OR_ID } from '../../config'
 import { conflict, mixins, camelToSnake } from '../../utils'
-import { patch, toVNode, toHTML, h } from './snabbdom'
+import { patch, toVNode, toHTML, h, addNStoVNodeSvgChildren } from './snabbdom'
 import { beginRules } from '../rules'
 import renderInlines from './renderInlines'
 import renderBlock from './renderBlock'
@@ -175,7 +175,7 @@ class StateRender {
     const children = blocks.map(block => {
       return this.renderBlock(null, block, activeBlocks, matches, true)
     })
-
+    addNStoVNodeSvgChildren(children)
     const newVdom = h(selector, children)
     const rootDom = document.querySelector(selector) || this.container
     const oldVdom = toVNode(rootDom)

src/muya/lib/parser/render/snabbdom.js

@@ -17,3 +17,21 @@ export const htmlToVNode = html => { // helper function for convert html to vnod
   wrapper.innerHTML = html
   return toVNode(wrapper).children
 }
+
+const addNS = ({ data, children, sel }) => {
+  data.ns = 'http://www.w3.org/2000/svg'
+  if (sel !== 'foreignObject' && children !== undefined) {
+    for (const vNode of children) {
+      if (vNode.data === undefined) continue
+      addNS(vNode)
+    }
+  }
+}
+
+export const addNStoVNodeSvgChildren = (children = []) => {
+  for (const vNode of children) {
+    if (vNode.data === undefined) continue
+    if (vNode.sel.startsWith('svg')) addNS(vNode)
+    addNStoVNodeSvgChildren(vNode.children)
+  }
+}