QGIS plugin open the dialog window on right click on map

Question

I am trying to execute a code on Left Click and Right Click should stop code execution and reopen the plugin dialog.

My code: This class is created for mouse click on the map. Here I do not really understand the way to stop plugin, instead I am trying to relaunch plugin dialog window to be able to add some variables in it later.

class PointTool(QgsMapTool):   
    def __init__(self, canvas):
        QgsMapTool.__init__(self, canvas)
        self.canvas = canvas 
        self.iface = iface
    def canvasReleaseEvent(self, event):
        #Get the click
        if event.button() == QtCore.Qt.RightButton:
            x = event.pos().x()
            y = event.pos().y()

            point = self.canvas.getCoordinateTransform().toMapCoordinates(x, y)
            x1=point[0]
            y1=point[1]
            self.iface.messageBar().pushMessage("RIGHT BUTTON COORDINATES: "+str(round(point[0],1))+","+str(round(point[1],1))+"</a>", duration=7)
##### HERE I AM TRYING TO RELAUNCH THE PLUGIN DIALOG
            rightaction = myplag(iface)
            rightaction.run()

        elif event.button() == QtCore.Qt.LeftButton:
            x = event.pos().x()
            y = event.pos().y()

            point = self.canvas.getCoordinateTransform().toMapCoordinates(x, y)
            x1=point[0]
            y1=point[1]

            self.iface.messageBar().pushMessage("LEFT BUTTON COORDINATES: "+str(round(point[0],1))+","+str(round(point[1],1))+"</a>", duration=7)

and below is a standard plugin class that I edited in def run(self):

class myplag:
    """QGIS Plugin Implementation."""

    def __init__(self, iface):
        """Constructor.

        :param iface: An interface instance that will be passed to this class
            which provides the hook by which you can manipulate the QGIS
            application at run time.
        :type iface: QgsInterface
        """
        # Save reference to the QGIS interface
        self.iface = iface
        # initialize plugin directory
        self.plugin_dir = os.path.dirname(__file__)
        # initialize locale
        locale = QSettings().value('locale/userLocale')[0:2]
        locale_path = os.path.join(
            self.plugin_dir,
            'i18n',
            'myplag_{}.qm'.format(locale))

        if os.path.exists(locale_path):
            self.translator = QTranslator()
            self.translator.load(locale_path)
            QCoreApplication.installTranslator(self.translator)

        # Declare instance attributes
        self.actions = []
        self.menu = self.tr(u'&myplag')

        # Check if plugin was started the first time in current QGIS session
        # Must be set in initGui() to survive plugin reloads
        self.first_start = None

    # noinspection PyMethodMayBeStatic
    def tr(self, message):

        # noinspection PyTypeChecker,PyArgumentList,PyCallByClass
        return QCoreApplication.translate('myplag', message)


    def add_action(
        self,
        icon_path,
        text,
        callback,
        enabled_flag=True,
        add_to_menu=True,
        add_to_toolbar=True,
        status_tip=None,
        whats_this=None,
        parent=None):

        icon = QIcon(icon_path)
        action = QAction(icon, text, parent)
        action.triggered.connect(callback)
        action.setEnabled(enabled_flag)

        if status_tip is not None:
            action.setStatusTip(status_tip)

        if whats_this is not None:
            action.setWhatsThis(whats_this)

        if add_to_toolbar:
            # Adds plugin icon to Plugins toolbar
            self.iface.addToolBarIcon(action)

        if add_to_menu:
            self.iface.addPluginToMenu(
                self.menu,
                action)

        self.actions.append(action)

        return action

    def initGui(self):
        """Create the menu entries and toolbar icons inside the QGIS GUI."""

        icon_path = ':/plugins/myplag/icon.png'
        self.add_action(
            icon_path,
            text=self.tr(u''),
            callback=self.run,
            parent=self.iface.mainWindow())

        # will be set False in run()
        self.first_start = True


    def unload(self):
        """Removes the plugin menu item and icon from QGIS GUI."""
        for action in self.actions:
            self.iface.removePluginMenu(
                self.tr(u'&myplag'),
                action)
            self.iface.removeToolBarIcon(action)

#    def display_point(pointTool):
#        try:
#            print(pointTool.x(), pointTool.y())
#        except AttributeError:
#            pass

    def run(self):
        """Run method that performs all the real work"""


        # Create the dialog with elements (after translation) and keep reference
        # Only create GUI ONCE in callback, so that it will only load when the plugin is started
        if self.first_start == True:
            self.first_start = False
            self.dlg = myplagDialog()
        # show the dialog
        self.dlg.show()
        # Run the dialog event loop
        result = self.dlg.exec_()
        # See if OK was pressed
        if result:
            # a reference to our map canvas
            tool = PointTool(iface.mapCanvas())
            iface.mapCanvas().setMapTool(tool)

When I Right click, it gives me error:

'myplag' object has no attribute 'dlg'

Answer 1

There are a few problems with your code. Below is a minimal plugin example which should help you out. You do not want to try to relaunch your plugin (create a new instance of your plugin class). Instead, you should add a parent parameter to your map tool class constructor and pass in the plugin dialog when you instantiate the map tool class. This will allow you to access the dialog and it's widgets from inside the map tool class and simply show it on the right mouse click using self.parent.show().

I have added some comments to the code below which is based on the minimal plugin example from Martin Dobias here.

It is a simple, working example with all classes and methods within the __init__.py file and this example shows how I prefer to structure my plugins. I have also included the metadata.txt file so that you you can save both these files in a folder and copy to your plugins directory, then activate in plugin manager to test.

from qgis.gui import QgsMapTool
from qgis.core import Qgis

from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QAction, QDialog, QLabel, QPushButton, QVBoxLayout

def classFactory(iface):
    return MapToolPlugin(iface)

# Main Plugin class
class MapToolPlugin:
    def __init__(self, iface):
        self.iface = iface
        self.canvas = self.iface.mapCanvas()
        self.dlg = MapToolPluginDialog()
        # pass in plugin dialog as parent (1st argument) to map tool constructor
        self.map_tool = ExampleMapTool(self.dlg, self.iface, self.canvas)

    def initGui(self):
        self.action = QAction('Go!', self.iface.mainWindow())
        self.action.triggered.connect(self.run)
        self.iface.addToolBarIcon(self.action)
        # connect dialog button signals to slot methods here (in initGui() method)
        self.dlg.ok_btn.clicked.connect(self.set_map_tool)

    def unload(self):
        self.iface.removeToolBarIcon(self.action)
        del self.action

    def run(self):
        self.dlg.lbl.setText('')
        self.dlg.show()
        
    def set_map_tool(self):
        self.canvas.setMapTool(self.map_tool)
        self.dlg.hide()

        
class MapToolPluginDialog(QDialog):
    def __init__(self):
        QDialog.__init__(self)
        self.setGeometry(200, 200, 600, 250)
        self.lbl = QLabel('Get clicked coordinates', self)
        self.ok_btn = QPushButton('Set Map Tool', self)
        self.layout = QVBoxLayout(self)
        self.layout.addWidget(self.lbl)
        self.layout.addWidget(self.ok_btn)
    
# Map tool class; takes parent & iface parameters in constructor
class ExampleMapTool(QgsMapTool):
    def __init__(self, parent, iface, canvas):
        self.parent = parent
        self.iface = iface
        self.canvas = canvas
        QgsMapTool.__init__(self, self.canvas)
        
    def canvasReleaseEvent(self, event):
        click_point = event.mapPoint()
        posx = click_point.x()
        posy = click_point.y()
        if event.button() == Qt.RightButton:
            # access self.parent object
            self.parent.lbl.setText(f'Click Position: {posx}, {posy}')
            # access self.iface object
            self.iface.actionPan().trigger()
            # call show() on parent object (the plugin dialog)
            self.parent.show()
        elif event.button() == Qt.LeftButton:
            self.iface.messageBar().pushMessage(f'Click Position: {posx}, {posy}',
                                                Qgis.Info, 5)

Metadata file:

[general]
name=MapToolPlugin
description=Map Tool plugin
about=Trivial example of a plugin with a map tool
version=1.0
qgisMinimumVersion=3.0
author=Ben Wirf
[email protected]
repository=URL to the code repository

Short screencast showing result: