How to make the "add html" item in the layout display text?

Question

I tried to make the "add html" item in the layout display a paragraph of text.This code works well in Python console:

project = QgsProject.instance()
layout_manager = project.layoutManager()
template_layout = layout_manager.layoutByName('test')
layout = template_layout.clone()
item = layout.itemById('html')
if isinstance(item , QgsLayoutFrame):
 multi_frame = item.multiFrame() 
 if isinstance(multi_frame, QgsLayoutItemHtml):
 html = multi_frame
 
item.setFrameEnabled(False)
html.setContentMode(QgsLayoutItemHtml.ManualHtml)
html.setHtml('this is a test!')
html.loadHtml() 
settings = QgsLayoutExporter.ImageExportSettings()
settings.dpi = 300 
output_path = r"D:\a.jpg"
exporter = QgsLayoutExporter(layout)
exporter.exportToImage(output_path, settings) 
layout_manager.removeLayout(layout)

But the same code cannot work properly in the Processing ToolBox:

def processAlgorithm(self,parameters: dict[str, Any],context: QgsProcessingContext,feedback: QgsProcessingFeedback,) -> dict[str, Any]:
 ...
 project = context.project()
 layout_manager = project.layoutManager()
 template_layout = layout_manager.layoutByName('test')
 layout = template_layout.clone()
 item = layout.itemById('html')
 if isinstance(item , QgsLayoutFrame):
 multi_frame = item.multiFrame() 
 if isinstance(multi_frame, QgsLayoutItemHtml):
 html = multi_frame
 
 item.setFrameEnabled(False)
 html.setContentMode(QgsLayoutItemHtml.ManualHtml)
 html.setHtml('this is a test!')
 html.loadHtml() 
 settings = QgsLayoutExporter.ImageExportSettings()
 settings.dpi = 300 
 output_path = r"D:\b.jpg"
 exporter = QgsLayoutExporter(layout)
 exporter.exportToImage(output_path, settings) 
 layout_manager.removeLayout(layout)
 ...

What happened and how should I modify it?

• Ben W: gis.stackexchange.com/questions/493906/…
• user316887: thank you!thank you very much!
• Andrea Giudiceandrea: Please provide the exact QGIS version used and explain what do you mean exactly with <<cannot work properly>>.
• user316887: html item display nothing when the code run in the Processing ToolBox. thanks Ben W,i get "processing algorithms are run in a background thread by default and any non-thread-safe API calls made in the processAlgorithm() method will result in crashes & unexpected behavior".