6

I want to get x/y coordinates of a point on mouse click for a point and need to use those coordinates to evaluate other values as per other modules already define.

How can I get x/y coordinates on mouse click in QGIS and print those in PyQGIS?

1
  • You need QgsMapToolEmitPoint class to do that (please, see my answer).
    – xunilk
    Commented Aug 30, 2017 at 1:05

1 Answer 1

16

You need QgsMapToolEmitPoint class to do that. Following code works well for that purpose:

from qgis.gui import QgsMapToolEmitPoint

def display_point( pointTool ): 

    print '({:.4f}, {:.4f})'.format(pointTool[0], pointTool[1])

# 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 )

However, if you prefer a class, following code can also be used:

from qgis.gui import QgsMapToolEmitPoint

class PrintClickedPoint(QgsMapToolEmitPoint):
    def __init__(self, canvas):
        self.canvas = canvas
        QgsMapToolEmitPoint.__init__(self, self.canvas)

    def canvasPressEvent( self, e ):
        point = self.toMapCoordinates(self.canvas.mouseLastXY())
        print '({:.4f}, {:.4f})'.format(point[0], point[1])

canvas_clicked = PrintClickedPoint( iface.mapCanvas() )
iface.mapCanvas().setMapTool( canvas_clicked ) 
3
  • 1
    This worked, thank you. May be you could add how to unset the listener: unsetMapTool(canvas_clicked) Commented Jul 29, 2019 at 14:11
  • When you try to use your own maptool in this case, it does not output anything to the console - is there are a reason for that? So lets say you set canvas.setMapTool( pointTool ) - it outputs noting to the console, yet the crosshair shows on the mapcanvas. Thanks @xunilk Commented Nov 17, 2020 at 19:22
  • I'm adding these lines to a function inside a plugin, and nothing happens... not even the crosshair. Error log is "NoneType: None" (I can keep working with the plugin, just the focus shifts from the plugin dialog to QGIS, that's all)...
    – S.E.
    Commented Apr 21, 2022 at 16:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.