code: def exportFormatChanged(self, item, prev):
      if item is None:
          self.currentExporter = None
          self.ui.paramTree.clear()
          return
      expClass = item.expClass
      exp = expClass(item=self.ui.itemTree.currentItem().gitem)
  
      params = exp.parameters()
  
      if params is None:
          self.ui.paramTree.clear()
      else:
          self.ui.paramTree.setParameters(params)
      self.currentExporter = exp
      self.ui.copyBtn.setEnabled(exp.allowCopy)
  
imports: from ..None import exporters
  from ..None import functions
  from ..graphicsItems.PlotItem import PlotItem
  from ..graphicsItems.ViewBox import ViewBox
  from ..Qt import QtCore, QtWidgets
  from .None import exportDialogTemplate_generic
label_desc: Use image node_id 7 for calling the ExportDialog obj's underlying member method code with example usage: obj.exportFormatChanged(item, prev) without return types