Vertex tool has highlighting & selecting mismatch

[tylerchism]

What is the bug or the crash?

vertex tool activated for a single polygon in one layer will sometimes trigger vertex highlighting with mouse hover activated for separate polygon in separate layer. The "correct" polygon does not respond to vertex clicks. The "wrong" polygon responds to vertex clicks, but the clicks activate a random vertex of the "correct" polygon.

A bare bones test script has been provided to reproduce this issue.

Steps to reproduce the issue

1. Start with fresh Qgis instance and no background map (just for clean viewing) and run this script in the console:

from qgis.PyQt.QtCore import QVariant, Qt
from qgis.PyQt.QtWidgets import QMenu, QAction
from qgis.core import (
    QgsProject,
    QgsVectorLayer,
    QgsField,
    QgsFeature,
    QgsGeometry,
    QgsPointXY,
    QgsFields,
    QgsWkbTypes,
    QgsRectangle,
    QgsFeatureRequest
)
from qgis.gui import QgsMapCanvas, QgsLayerTreeMapCanvasBridge, QgsMapTool, QgsRubberBand
from qgis.utils import iface

# Remove existing layers for a clean environment
QgsProject.instance().removeAllMapLayers()

# Create a temporary polygon layer
polygon_layer = QgsVectorLayer("Polygon?crs=EPSG:4326", "Test Polygons", "memory")
pr = polygon_layer.dataProvider()

# Add an ID field
pr.addAttributes([QgsField("id", QVariant.Int)])
polygon_layer.updateFields()

# Define two polygons
polygon1 = QgsFeature()
polygon1.setFields(polygon_layer.fields())
polygon1.setAttribute("id", 1)
polygon1.setGeometry(QgsGeometry.fromPolygonXY([[QgsPointXY(-10, -10), QgsPointXY(0, -10), QgsPointXY(0, 0), QgsPointXY(-10, 0), QgsPointXY(-10, -10)]]))

polygon2 = QgsFeature()
polygon2.setFields(polygon_layer.fields())
polygon2.setAttribute("id", 2)
polygon2.setGeometry(QgsGeometry.fromPolygonXY([[QgsPointXY(10, 10), QgsPointXY(20, 10), QgsPointXY(20, 20), QgsPointXY(10, 20), QgsPointXY(10, 10)]]))

# Add polygons to the layer
pr.addFeatures([polygon1, polygon2])
polygon_layer.updateExtents()

# Add the layer to the project
QgsProject.instance().addMapLayer(polygon_layer)

# Custom Map Tool
class RightClickEditTool(QgsMapTool):
    def __init__(self, canvas):
        super().__init__(canvas)
        self.canvas = canvas
        self.tmp_layer = None
        self.previous_tmp_layer = None

    def canvasPressEvent(self, event):
        if event.button() == Qt.RightButton:
            # Get the map point where the user clicked
            point = self.toMapCoordinates(event.pos())

            # Identify features at the clicked point
            layer = polygon_layer  # Use our specific polygon layer
            if not layer:
                return

            features = []
            # Adjust the search radius as needed
            rect = QgsRectangle(point.x() - 0.0001, point.y() - 0.0001, point.x() + 0.0001, point.y() + 0.0001)
            request = QgsFeatureRequest().setFilterRect(rect)
            for feature in layer.getFeatures(request):
                features.append(feature)

            if features:
                # If features are found, show the context menu
                feature = features[0]  # Take the first feature
                self.showContextMenu(event, feature)

    def showContextMenu(self, event, feature):
        menu = QMenu()
        edit_action = QAction("Edit Polygon", menu)
        edit_action.triggered.connect(lambda: self.editPolygon(feature))
        menu.addAction(edit_action)
        menu.exec_(event.globalPos())

    def editPolygon(self, feature):
        # Remove previous temporary layer if it exists
        if self.previous_tmp_layer:
            if self.previous_tmp_layer.isEditable():
                self.previous_tmp_layer.commitChanges()
            QgsProject.instance().removeMapLayer(self.previous_tmp_layer.id())
            self.previous_tmp_layer = None

        # Create a temporary layer and copy the feature into it
        self.tmp_layer = QgsVectorLayer("Polygon?crs=EPSG:4326", "Temporary Edit Layer", "memory")
        pr = self.tmp_layer.dataProvider()
        pr.addAttributes(feature.fields())
        self.tmp_layer.updateFields()

        tmp_feature = QgsFeature()
        tmp_feature.setFields(feature.fields())
        tmp_feature.setGeometry(feature.geometry())
        tmp_feature.setAttributes(feature.attributes())

        pr.addFeatures([tmp_feature])
        self.tmp_layer.updateExtents()

        # Add the temporary layer to the project
        QgsProject.instance().addMapLayer(self.tmp_layer)

        # Start editing and activate the vertex tool
        self.tmp_layer.startEditing()
        iface.setActiveLayer(self.tmp_layer)
        iface.actionVertexTool().trigger()

        # Store the temporary layer to remove it later
        self.previous_tmp_layer = self.tmp_layer

    def deactivate(self):
        # Clean up when the tool is deactivated
        if self.previous_tmp_layer:
            if self.previous_tmp_layer.isEditable():
                self.previous_tmp_layer.commitChanges()
            #QgsProject.instance().removeMapLayer(self.previous_tmp_layer.id())
            QgsProject.instance().layerTreeRoot().removeChildNode(self.previous_tmp_layer.id())
            self.previous_tmp_layer = None
        super().deactivate()

# Instantiate and activate the custom map tool
canvas = iface.mapCanvas()
edit_tool = RightClickEditTool(canvas)
canvas.setMapTool(edit_tool)

2. A custom click tool will now be active and you can right click on one of the two polygons to select "edit polygon"
3. Click edit polygon and you will see it triggers the vertex tool for that polygon and mouse hovering will indicate normal behavior
4. Click the toggle editing icon to exit editing for that polygon
5. Right click the other polygon and see if mouse hovering shows normal vertex highlighting for that polygon
6. Toggle editing again and repeat steps jumping back and forth between polygons until the issue arises, it happens every time within ten tries.

Versions

QGIS version
3.34.10-Prizren
QGIS code revision
113de9e
Qt version
5.15.13
Python version
3.12.5
GDAL/OGR version
3.9.2
PROJ version
9.4.0
EPSG Registry database version
v11.004 (2024-02-24)
GEOS version
3.12.2-CAPI-1.18.2
SQLite version
3.45.1
PDAL version
2.6.3
PostgreSQL client version
16.2
SpatiaLite version
5.1.0
QWT version
6.2.0
QScintilla2 version
2.14.1
OS version
Windows 10 Version 2009

Active Python plugins
debug_vs
0.7
flight-planner-qgis
1.0.10
gml_db_browser
0.1
line-builder-qgis
2.2.12
MultipleLayerSelection
2.0
pluginbuilder3
3.2.1
plugin_reloader
0.9.1
postgis_geoprocessing
0.9
qgis-feature_class_manager
v2.12.01
QGIS3-getWKT
1.4
quick_map_services
0.19.29
db_manager
0.1.20
MetaSearch
0.3.6
processing
2.12.99

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

No response

[gd-33]

I've noticed this problem also. Your recreation of the issue from QGIS first principals here really highlights the issue. I'd like to know if this is actually a bug or if there is just a simple line of code which is missing which would sidestep this issue...

[troopa81]

Very likely fixed with #60562