Getting coordinates from mouse click in QGIS 3 (python plugin)

Question

I am trying to get coordinates from a mouse click in QGIS 3 and python 3 using the plugin builder.

I have tried using the response from this post, and i can manage to get the coordinates printed to the python console in QGIS but at the same time i get the message that "'TypeError: 'QgsMapToolEmitPoint' object is not iterable" or "'QgsMapToolEmitPoint' object does not support indexing"

I can't remember i ever seen a python program causing an error but still manage to compute and output the wanted result. The "not iterable" error traces back to the line with the for loop "for point in ... " the "does not support indexing" error is caused if i do e.g. x = pointTool[0]

Here is a version of the code:

from qgis.gui import QgsMapToolEmitPoint 

def display_point(pointTool):
    #print(pointTool)
    cood = []
    for point in pointTool:
        cood.append(point)
    print(cood)

# a reference to our map canvas
canvas = iface.mapCanvas()

# this QGIS tool emits as QgsPoint after each click on the map canvas
pointTool = QgsMapToolEmitPoint(canvas)

pointTool.canvasClicked.connect(display_point)

canvas.setMapTool(pointTool)

display_point(pointTool)

Answer 1

I have a little bit of a hard time getting the "canvasReleaseEvent" to return the x,y coordinates. At the moment i am writing my code into that function since it does output the x, y. (simply by stating "x=point.x()" etc).

I think i will try @xunilk's code and see if that would be easier.

https://webgeodatavore.github.io/pyqgis-samples/gui-group/QgsMapTool.html

# coding: utf-8
from PyQt4.QtCore import Qt
from qgis.gui import QgsMapTool
from qgis.utils import iface


class SendPointToolCoordinates(QgsMapTool):
    """ Enable to return coordinates from clic in a layer.
    """
    def __init__(self, canvas, layer):
        """ Constructor.
        """
        QgsMapTool.__init__(self, canvas)
        self.canvas = canvas
        self.layer = layer
        self.setCursor(Qt.CrossCursor)

    def canvasReleaseEvent(self, event):
        point = self.toLayerCoordinates(self.layer, event.pos())

        print(point.x(), point.y())

layer, canvas = iface.activeLayer(), iface.mapCanvas()

send_point_tool_coordinates = SendPointToolCoordinates(
    canvas,
    layer
)
canvas.setMapTool(send_point_tool_coordinates)

Answer 2

In QGIS 3 you need a function something different. Following version of your code it can print mouse click:

from qgis.gui import QgsMapToolEmitPoint 

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

# a reference to our map canvas
canvas = iface.mapCanvas()

# this QGIS tool emits as QgsPoint after each click on the map canvas
pointTool = QgsMapToolEmitPoint(canvas)

pointTool.canvasClicked.connect(display_point)

canvas.setMapTool(pointTool)

display_point(pointTool)

as it can be observed at following image:

Answer 3

In QGIS 3.16 I did it in a simple way. I created a plugin-button. After clicking oin that (1) I can click in the map and get the coordinate as a self.iface.messageBar().pushMessage.

from qgis.PyQt.QtCore import QSettings, QTranslator, QCoreApplication
from qgis.PyQt.QtGui import QIcon
from qgis.PyQt.QtWidgets import QAction
from qgis.PyQt.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from qgis.PyQt.QtSql import QSqlDatabase, QSqlQuery
from PyQt5.QtWidgets import QTableView, QApplication
from urllib.request import urlopen
from qgis.core import *
from qgis.gui import *
from qgis.gui import QgsMapToolEmitPoint 
from qgis.utils import iface
from qgis.gui import QgsMapTool
# Initialize Qt resources from file resources.py
from .resources import *
# Import the code for the dialog
from .webgis_connector_dialog import WebGISConnectorDialog
import os.path
import sys
import urllib3
class PointTool(QgsMapTool):

    def init(self, canvas):
        QgsMapTool.init(self, canvas)
        self.canvas = canvas 
        self.iface = iface
def canvasPressEvent(self, event):
    pass

def canvasMoveEvent(self, event):
    x = event.pos().x()
    y = event.pos().y()

    point = self.canvas.getCoordinateTransform().toMapCoordinates(x, y)

def canvasReleaseEvent(self, event):
    #Get the click
    x = event.pos().x()
    y = event.pos().y()

    point = self.canvas.getCoordinateTransform().toMapCoordinates(x, y)
    x1=point[0]
    y1=point[1]
    link="'http://gisground2.ibbenbueren.intern?koordinate="+str(x1)+","+str(y1)+"'"
    #qgis.utils.iface.messageBar().pushMessage("hhhh", u"Gespeichert ist folgender Layer: "+link, duration=7)

    self.iface.messageBar().pushMessage("Link zum WebGIS: <a href="+link+">http://webgis.ibbenbueren.intern?koordinate="+str(round(point[0],1))+","+str(round(point[1],1))+"</a>", duration=7)

def activate(self):
    pass

def deactivate(self):
    pass

def isZoomTool(self):
    return False

def isTransient(self):
    return False

def isEditTool(self):
    return True


class WebGISConnector:
    """QGIS Plugin Implementation."""
def __init__(self, iface):
    self.iface = iface

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',
        'WebGISConnector_{}.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'&WebGIS Connector')

    # 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):
    """Get the translation for a string using Qt translation API.

    We implement this ourselves since we do not inherit QObject.

    :param message: String for translation.
    :type message: str, QString

    :returns: Translated version of message.
    :rtype: QString
    """
    # noinspection PyTypeChecker,PyArgumentList,PyCallByClass
    return QCoreApplication.translate('WebGISConnector', 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):
    """Add a toolbar icon to the toolbar.

    :param icon_path: Path to the icon for this action. Can be a resource
        path (e.g. ':/plugins/foo/bar.png') or a normal file system path.
    :type icon_path: str

    :param text: Text that should be shown in menu items for this action.
    :type text: str

    :param callback: Function to be called when the action is triggered.
    :type callback: function

    :param enabled_flag: A flag indicating if the action should be enabled
        by default. Defaults to True.
    :type enabled_flag: bool

    :param add_to_menu: Flag indicating whether the action should also
        be added to the menu. Defaults to True.
    :type add_to_menu: bool

    :param add_to_toolbar: Flag indicating whether the action should also
        be added to the toolbar. Defaults to True.
    :type add_to_toolbar: bool

    :param status_tip: Optional text to show in a popup when mouse pointer
        hovers over the action.
    :type status_tip: str

    :param parent: Parent widget for the new action. Defaults None.
    :type parent: QWidget

    :param whats_this: Optional text to show in the status bar when the
        mouse pointer hovers over the action.

    :returns: The action that was created. Note that the action is also
        added to self.actions list.
    :rtype: QAction
    """

    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.addPluginToWebMenu(
            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/webgis_connector/icon.png'
    self.add_action(
        icon_path,
        text=self.tr(u'WebGIS Connector'),
        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.removePluginWebMenu(
            self.tr(u'&WebGIS Connector'),
            action)
        self.iface.removeToolBarIcon(action)


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 = WebGISConnectorDialog()



    self.iface.messageBar().pushMessage("Bitte jetzt in die Karte klicken...", duration=3)  
    tool = PointTool(iface.mapCanvas())
    iface.mapCanvas().setMapTool(tool)