Hi Bernhard, what about
iface.mapCanvas().extentsChanged.connect(lambda: print("the extent has
changed!!!"))
Or something more usefull like
def extent_has_changed_slot():
print(iface.mapCanvas().extent())
iface.mapCanvas().extentsChanged.connect(extent_has_changed_slot)
Btw, the *signal* is 'extentsChanged', 'emitExtentsChanged' is a
*function*, which will trigger the emit of the signal.
So:
a) 'xxx' ist the signal-object, above 'iface.mapCanvas().extentsChanged'
b) extentsChanged is a signal without parameters, signals with
parameters can be used in slot-functions with appropriate signatures.
Below a sample for a signal with parameters, see
https://api.qgis.org/api/classQgsMapCanvas.html#a6c6f74644c9b273917a29e77b6400e89
def map_tool_was_set_slot(new_tool,old_tool):
print(new_tool,old_tool)
iface.mapCanvas().mapToolSet.connect(map_tool_was_set_slot)
Hth
Ludwig
Am 14.03.24 um 15:48 schrieb Bernhard Seckinger via QGIS-User:
Hi,
I'm trying to write a plugin, that gets into action, whenever the user moves
or zooms the main map. I found the QgsMapCanvas::emitExtentsChanged() signal.
This is probably exactly, what I need. But I don't know, how to "catch" this
signal. I guess, this is somehow done with pyqtSignals, but I don't understand
how...
I found a tutorial (1) which explains how to use pyqtSignal with self defined
signals. I think I got this. But now I need to catch a signal which is defined
in the library. How to connect to this signal?
From what I understand, my code should be something like:
def __init__():
# with some pyqtSignal xxx:
xxx.connect(my_fun)
def my_fun(some parameters?):
# code to execute when extents changed
So two question remain:
a) What is xxx above?
b) Does "my_fun" need some parameters?
Any help is appreciated!
Thanks, Bernhard
(1) https://gis-ops.com/qgis-3-plugin-tutorial-pyqt-signal-slot-explained/
--
Bernhard Seckinger <bernhard.seckin...@bueffee.de>
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