code: def _generateItemSvg(item, nodes=None, root=None, options=None):
      """This function is intended to work around some issues with Qt's SVG generator
      and SVG in general.
  
      .. warning::
          This function, while documented, is not considered part of the public
          API. The reason for its documentation is for ease of referencing by
          :func:`~pyqtgraph.GraphicsItem.generateSvg`. There should be no need
          to call this function explicitly.
  
      1. Qt SVG does not implement clipping paths. This is absurd.
      The solution is to let Qt generate SVG for each item independently,
      then glue them together manually with clipping.  The format Qt generates
      for all items looks like this:
  
      .. code-block:: xml
  
          <g>
              <g transform="matrix(...)">
                  one or more of: <path/> or <polyline/> or <text/>
              </g>
              <g transform="matrix(...)">
                  one or more of: <path/> or <polyline/> or <text/>
              </g>
              . . .
          </g>
  
      2. There seems to be wide disagreement over whether path strokes
      should be scaled anisotropically.  Given that both inkscape and
      illustrator seem to prefer isotropic scaling, we will optimize for
      those cases.
  
      .. note::
  
          see: http://web.mit.edu/jonas/www/anisotropy/
  
      3. Qt generates paths using non-scaling-stroke from SVG 1.2, but
      inkscape only supports 1.1.
  
      Both 2 and 3 can be addressed by drawing all items in world coordinates.
  
      Parameters
      ----------
      item : :class:`~pyqtgraph.GraphicsItem`
          GraphicsItem to generate SVG of
      nodes : dict of str, optional
          dictionary keyed on graphics item names, values contains the
          XML elements, by default None
      root : :class:`~pyqtgraph.GraphicsItem`, optional
          root GraphicsItem, if none, assigns to `item`, by default None
      options : dict of str, optional
          Options to be applied to the generated XML, by default None
  
      Returns
      -------
      tuple
          tuple where first element is XML element, second element is
          a list of child GraphicItems XML elements
      """
  
      profiler = debug.Profiler()
      if options is None:
          options = {}
  
      if (
          nodes is None
      ):  ## nodes maps all node IDs to their XML element.
          ## this allows us to ensure all elements receive unique names.
          nodes = {}
  
      if root is None:
          root = item
  
      ## Skip hidden items
      if hasattr(item, "isVisible") and not item.isVisible():
          return None
  
      with contextlib.suppress(NotImplementedError, AttributeError):
          # If this item defines its own SVG generator, use that.
          return item.generateSvg(nodes)
      ## Generate SVG text for just this item (exclude its children; we'll handle them later)
      if isinstance(item, QtWidgets.QGraphicsScene):
          xmlStr = "<g>\n</g>\n"
          doc = xml.parseString(xmlStr)
          childs = [i for i in item.items() if i.parentItem() is None]
      elif item.__class__.paint == QtWidgets.QGraphicsItem.paint:
          xmlStr = "<g>\n</g>\n"
          doc = xml.parseString(xmlStr)
          childs = item.childItems()
      else:
          childs = item.childItems()
  
          dx = dy = 0.0
          sx = sy = 1.0
  
          if isinstance(item, PlotCurveItem):
              # Workaround for lack of precision in SVG numbers
              # We shift curves to be centered about (0, 0) and scaled such that
              # they fit within the region of float32 values that we can
              # distinguish between similar but different values
              rect = item.viewRect()
              x_range = rect.right() - rect.left()
              dx = rect.left() + (x_range / 2)
  
              y_range = rect.top() - rect.bottom()
              dy = rect.bottom() + y_range / 2
  
              sx = 1 / abs(x_range)
              sy = 1 / abs(y_range)
  
              item.blockSignals(True)
  
              xDataOriginal = item.xData
              yDataOriginal = item.yData
              # use deepcopy of data to not mess with other references...
              item.setData(
                  (xDataOriginal.copy() - dx) * sx,
                  (yDataOriginal.copy() - dy) * sy,
              )
              item.blockSignals(False)
  
          manipulate = QtGui.QTransform(1 / sx, 0, 0, 1 / sy, dx, dy)
          tr = itemTransform(item, item.scene())
          # offset to corner of root item
          if isinstance(root, QtWidgets.QGraphicsScene):
              rootPos = QtCore.QPoint(0, 0)
          else:
              rootPos = root.scenePos()
  
          # handle rescaling from the export dialog
          if hasattr(root, "boundingRect"):
              resize_x = options["width"] / root.boundingRect().width()
              resize_y = (
                  options["height"] / root.boundingRect().height()
              )
          else:
              resize_x = resize_y = 1
          tr2 = QtGui.QTransform(
              resize_x, 0, 0, resize_y, -rootPos.x(), -rootPos.y()
          )
          tr = manipulate * tr * tr2
  
          arr = QtCore.QByteArray()
          buf = QtCore.QBuffer(arr)
          svg = QtSvg.QSvgGenerator()
          svg.setOutputDevice(buf)
          dpi = (
              QtGui.QGuiApplication.primaryScreen().logicalDotsPerInchX()
          )
          svg.setResolution(int(dpi))
          p = QtGui.QPainter()
          p.begin(svg)
          if hasattr(item, "setExportMode"):
              item.setExportMode(True, {"painter": p})
          try:
              p.setTransform(tr)
              opt = QtWidgets.QStyleOptionGraphicsItem()
              if (
                  item.flags()
                  & QtWidgets.QGraphicsItem.GraphicsItemFlag.ItemUsesExtendedStyleOption
              ):
                  opt.exposedRect = item.boundingRect()
              item.paint(p, opt, None)
          finally:
              p.end()
              ## Can't do this here--we need to wait until all children have painted as well.
              ## this is taken care of in generateSvg instead.
              # if hasattr(item, 'setExportMode'):
              #     item.setExportMode(False)
          doc = xml.parseString(arr.data())
  
      try:
          ## Get top-level group for this item
          g1 = doc.getElementsByTagName("g")[0]
          defs = doc.getElementsByTagName("defs")
          if len(defs) > 0:
              defs = [
                  n
                  for n in defs[0].childNodes
                  if isinstance(n, xml.Element)
              ]
      except:
          print(doc.toxml())
          raise
      profiler("render")
      ## Get rid of group transformation matrices by applying
      ## transformation to inner coordinates
      correctCoordinates(g1, defs, item, options)
      profiler("correct")
  
      ## decide on a name for this item
      baseName = item.__class__.__name__
      i = 1
      while True:
          name = baseName + "_%d" % i
          if name not in nodes:
              break
          i += 1
      nodes[name] = g1
      g1.setAttribute("id", name)
  
      ## If this item clips its children, we need to take care of that.
      childGroup = g1  ## add children directly to this node unless we are clipping
      if (
          not isinstance(item, QtWidgets.QGraphicsScene)
          and item.flags()
          & item.GraphicsItemFlag.ItemClipsChildrenToShape
      ):
          ## Generate svg for just the path
          path = QtWidgets.QGraphicsPathItem(
              item.mapToScene(item.shape())
          )
          item.scene().addItem(path)
          try:
              pathNode = _generateItemSvg(
                  path, root=root, options=options
              )[0].getElementsByTagName("path")[0]
              # assume <defs> for this path is empty.. possibly problematic.
          finally:
              item.scene().removeItem(path)
  
              ## and for the clipPath element
          clip = f"{name}_clip"
          clipNode = g1.ownerDocument.createElement("clipPath")
          clipNode.setAttribute("id", clip)
          clipNode.appendChild(pathNode)
          g1.appendChild(clipNode)
  
          childGroup = g1.ownerDocument.createElement("g")
          childGroup.setAttribute("clip-path", f"url(#{clip})")
          g1.appendChild(childGroup)
      profiler("clipping")
  
      ## Add all child items as sub-elements.
      childs.sort(key=lambda c: c.zValue())
      for ch in childs:
          csvg = _generateItemSvg(ch, nodes, root, options=options)
          if csvg is None:
              continue
          cg, cdefs = csvg
          childGroup.appendChild(
              cg
          )  ### this isn't quite right--some items draw below their parent (good enough for now)
          defs.extend(cdefs)
  
      profiler("children")
      return g1, defs
  
imports: import contextlib
  import re
  import xml.dom.minidom
  import numpy
  from ..None import PlotCurveItem, ScatterPlotItem, debug
  from ..None import functions
  from ..parametertree import Parameter
  from ..Qt import QtCore, QtGui, QtSvg, QtWidgets
  from .Exporter import Exporter
label_desc: Use image node_id 2 for calling a global function with example usage: _generateItemSvg(item, nodes, root, options) and returns: g1,  defs, None, item