Cannot send "mouse move" with left/right down with EnableTestAssistant

[notmatthancock]

As far as I can tell, the EnableTestAssistant only provides methods for creating "drag over" DragEvents, but does not provide the ability to create a mouse-move MouseEvent with left_down attribute set to True.

This seems like a straight-forward extension of EnableTestAssistant.mouse_move to include left_down and right_down keyword arguments to be included in the mouse event that is created in body of the function:

enable/enable/testing.py

Lines 275 to 276 in 4db18d2

	def mouse_move(self, interactor, x, y, window=None,
	alt_down=False, control_down=False, shift_down=False):

This functionality would be useful because (for example) the DragTool depends on mouse move events where the event has {left,right}_down set to True:

enable/enable/tools/drag_tool.py

Lines 146 to 148 in 55fc728

	def _drag_mouse_move(self, event):
	state = self._drag_state
	button_down = getattr(event, self.drag_button + "_down")

[aaronayres35]

I believe this functionality may already be possible via the mouse_down and mouse_up methods (but I haven't tried it explicitly to check yet)? One could call mouse_down with button="left" to trigger the left_down and then call mouse_move as needed. Alternatively, there exists a press_move_release method that might be applicable here. It effectively calls the mouse_down, mouse_move and mouse_up methods in order.
Does this process not create the desired outcome here?

It is very possible that, as is mentioned in the description "DragTool depends on mouse move events where the event has {left,right}_down set to True", and doing the above does not set {left,right}_down on the mouse_move event itself and doing the above only sets {left,right}_down on the first event created by mouse_down, but then for the mouse_move event it is unset. So, using it with DragTool does not have the expected effect. I imagine this is likely the case. If this is true then we may want to update press_move_release as well, to set {left,right}_down on the mouse_move event explicitly as well

[notmatthancock]

Unfortunately no. The implementation of mouse_move calls to create_mouse_event without feeding anything about mouse button up/down status. press_move_release essentially implements the various helpers in sequence, so its behavior is no different.

Example:

from enable.api import Component
from enable.testing import EnableTestAssistant


class MyComponent(Component):

    def normal_left_down(self, event):
        print(event.left_down)

    def normal_mouse_move(self, event):
        print(event.left_down)


assistant = EnableTestAssistant()
component = MyComponent(bounds=[100, 100])
assistant.mouse_down(component, 50, 50, button='left')
assistant.mouse_move(component, 50, 50)
assistant.mouse_move(component, 50, 75)

prints

True
<undefined>
<undefined>

[aaronayres35]

Unfortunately no. The implementation of mouse_move calls to create_mouse_event without feeding anything about mouse button up/down status. press_move_release essentially implements the various helpers in sequence, so its behavior is no different.

I see now, thank you! I was confused as this test was passing:

def test_mouse_move_after_mouse_down(self):
        test_assistant = EnableTestAssistant()
        component = Component(bounds=[100, 200])
        test_assistant.mouse_down(component, x=0, y=0)
        event = test_assistant.mouse_move(component, 10, 20)

        self.assertEqual(event.x, 10)
        self.assertEqual(event.y, 20)
        # left_down from calling mouse_dwn is carried into mouse move event
        self.assertTrue(event.left_down)

a print(event.left_down) reveals it is actually<undefined> which evaluates to True 🤦 .

Thank you for the example!

[notmatthancock]

a print(event.left_down) reveals it is actually which evaluates to True facepalm .

Eek. I think I recall some discussion on traits recently around the truthiness of <undefined>. I don't recall exactly where the discussion took place, but it might be a good example to show.

[mdickinson]

@aaronayres35 Could you track down where that undefined is coming from? Is Enable deliberately and consciously providing an undefined value here, or is this an artifact of general Traits machinery?

[aaronayres35]

@aaronayres35 Could you track down where that undefined is coming from? Is Enable deliberately and consciously providing an undefined value here, or is this an artifact of general Traits machinery?

@mdickinson the left_down trait on a MouseEvent object is a Readonly trait:

enable/enable/events.py

Line 136 in ba6f246

left_down = ReadOnly

which has a default of Undefined:
https://github.com/enthought/traits/blob/2b62cd9b39bcb9e4998eeab0b32a4e3127b3df66/traits/trait_types.py#L992-L1009