Putting a label beside QgsVertexMarker object

Question

Recently I learned how to create a point in the map independently from any layer, using QgsVertexMarker. Now, I would like to put a label beside it, using Python. However, I do not see an option 'label' or something like that belonging to the class QgsVertexMarker.

How to do this?

Answer 1

I think the closest you can get to labeling a vertex marker would be to use a QgsTextAnnotation.

So following on from your previous question, and based on Fran Raga's answer here and Stefan's question (for QGIS 2.X) here,

you could do something like:

canvas = iface.mapCanvas()

lon = 131.2
lat = -12.5

pnt = QgsPointXY(lon, lat)

m = QgsVertexMarker(canvas)
m.setCenter(pnt)
m.setColor(QColor('Black'))
m.setIconType(QgsVertexMarker.ICON_CIRCLE)
m.setIconSize(15)
m.setPenWidth(1)
m.setFillColor(QColor(0, 200, 0))

sym = QgsMarkerSymbol()
sym.setSize(0)
txt = QTextDocument('Point A')
lbl = QgsTextAnnotation(canvas)
lbl.setDocument(txt)
lbl.setFrameSize(QSizeF(50.0, 25.0))
lbl.setMapPosition(pnt)
lbl.setFrameSize(QSizeF(txt.size().width(),txt.size().height()))
lbl.setFrameOffsetFromReferencePoint(QPointF(10, 5))
lbl.setMarkerSymbol(sym)
i = QgsMapCanvasAnnotationItem(lbl, canvas)

#canvas.scene().removeItem(m)
#canvas.scene().removeItem(i)

Result:

You can play around with the map position and offset etc to move the annotation item around.

The documentation for the classes can be found here:

https://qgis.org/api/classQgsAnnotation.html

https://qgis.org/api/classQgsTextAnnotation.html