Getting coordinates of point on mouse click using PyQGIS

Question

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?

• xunilk: You need QgsMapToolEmitPoint class to do that (please, see my answer).

Answer 1

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 ) 

• Rodrigo E. Principe: This worked, thank you. May be you could add how to unset the listener: unsetMapTool(canvas_clicked)
• user1655130: 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
• S.E.: 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)...