Setting selection border color in red and save the map of the resulting selection

Question

I'm attempting to create a plugin in QGIS 3 in order to zoom on a selected feature and get the map picture exported in .jpg format.

I've been able to perform the zoom and selection of my selection, and now I want to add some color border to the selected feature using QgsHightlight :

def highlight_features():
    for i in couche_parcelles.selectedFeatures():
        h = QgsHighlight(canvas,i.geometry(),couche_parcelles)
        h.setColor(QColor(255,0,0))
        h.setWidth(10)

#================================Map Creation==================================
#project = QgsProject.instance()

mapSettings = canvas.mapSettings()
mapSettings.setOutputSize(QSize(1600,1100))
mapSettings.setOutputDpi(200)

render = QgsMapRendererSequentialJob(mapSettings)
render.start()
render.waitForFinished()

dir = r"C:\Users\[...]\Desktop"

img = render.renderedImage()
img.save(dir + "/" + "selection.jpg",'jpg')

It does make a pretty highlight border on QGIS software like this :

But then, once I get the map rendered, here's what I get generated by the script :

My question is, how can I get the highlight extracted with my selection on the map ? Because I'm not sure it has something to do with my canvas and I don't know if it's possible to embed my QgsHighlight in my canvas either

I've already seen this answer : Setting selection color transparent and border color red using PyQGIS? Which helped me to get the highlight on my selection borders but I can't figure out how to integrate it in my map rendering

Answer 1

Alright came up with another solution :

Instead of using QgsHighlight in order to get a border out of the selected feature, I've created a layer of my selected feature :

couche_parcelle = QgsProject.instance().mapLayersByName('3_parcelles_aix.shp')[0]
expr = "\"(attribute_table_column)\"='(fixed value)'"
selec = QgsExpression(expr)
selec_couche = couche_parcelle.getFeatures(QgsFeatureRequest(selec))
liste_selec = [i.id() for i in selec_couche]
couche_parcelle.selectByIds(liste_selec)
#couche_parcelle.selectedFeatureIds()

#Once the feature is selected, I grab the selected feature and create a temporary layer in memory
nouvelle_couche = couche_parcelle.materialize(QgsFeatureRequest().setFilterFids(couche_parcelle.selectedFeatureIds()))
QgsProject.instance().addMapLayer(nouvelle_couche)
nouvelle_couche.setName("parcelle_duplica")

Once done, I take the properties of my new layer nouvelle_couche in a variable I'll call props:

props = nouvelle_couche.renderer().symbol().symbolLayer(0).properties()
props['outline_color']='255,0,0,255'
props['outline_width']='3'
nouvelle_couche.renderer().setSymbol(QgsFillSymbol.createSimple(props))
nouvelle_couche.triggerRepaint()

Finally, it appears and gets on the generated map rendering, it's been tough but now it works