Adding Double Click Callback

[Nibba2018]

Referencing #226 , Adding Double Left Click Callback.
I will be adding examples & unittests soon.

Let me know if I am doing it wrong.
Thank You.

[codecov]

Codecov Report

Merging #231 into master will increase coverage by 0.02%.
The diff coverage is 89.74%.

@@            Coverage Diff             @@
##           master     #231      +/-   ##
==========================================
+ Coverage   88.46%   88.49%   +0.02%     
==========================================
  Files          17       17              
  Lines        4386     4423      +37     
  Branches      556      569      +13     
==========================================
+ Hits         3880     3914      +34     
  Misses        366      366              
- Partials      140      143       +3     

Impacted Files	Coverage Δ
fury/ui.py	86.13% <0.00%> (-0.16%)	⬇️
fury/interactor.py	96.92% <97.22%> (+0.53%)	⬆️

[Nibba2018]

@skoudoro I need some suggestions here...

According to this example they have overridden the OnLeftButtonDown by inheriting from vtkInteractorStyleTrackballCamera class. But the rest of the callbacks are implemented in a different way. So should I inherit both vtkInteractorStyleUser and vtkInteractorStyleTrackballCamera and implement the double click? or should I create a separate class for it?

I am also unable to implement my double click callback on an actor hence not being able to test my implementation. I need some help here with that.

Thanks.

[skoudoro]

Hi @Nibba2018,

So should I inherit both vtkInteractorStyleUser and vtkInteractorStyleTrackballCamera and implement the double click? or should I create a separate class for it?

inherit from vtkInteractorStyleUser so inherit from the current class

I am also unable to implement my double click callback on an actor hence not being able to test my implementation. I need some help here with that.

There are many ways to do it and it is not trivial. In your first test, you should do every in on_left_button_down. Then, when it works you can create a new custom event and use the invokeevent function. I will try to give you more details later this weekend but you can update this first. Look at all existing vtk event and How to create a custom event.

[pep8speaks]

Hello @Nibba2018! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file fury/tests/test_interactor.py:

Line 151:24: E127 continuation line over-indented for visual indent

Comment last updated at 2020-06-09 22:07:04 UTC

[Nibba2018]

Here's a test that I am running to test double click implementation where I change the color of the cube when double clicked on it.

from fury import actor, window, interactor
import numpy as np

cube = actor.cube(np.random.rand(1, 3), np.random.rand(1,3), (1,1,1), heights=np.random.rand(5))

def change_color(iren, obj):
	obj.SetColor(np.random.rand(3))
	iren.force_render()

interactor_style = interactor.CustomInteractorStyle()
interactor_style.add_active_prop(cube)
interactor_style.add_callback(cube, "LeftButtonPressEvent", change_color)

current_size = (800, 800)
showm = window.ShowManager(size=current_size, title="Double Click Test")
showm.scene.add(cube)
showm.start()

Apparantly I am having an error message being printed which I am not able to understand why. The output:

Initial state: (390, 379)
Final state: (390, 379)
Initial state: (390, 379)
Final state: (390, 379)
Double Clicked...
interactor is none
event name is LeftButtonPressEvent

interactor is none
event name is LeftButtonPressEvent

[skoudoro]

1. Can you differentiate LeftButtonPressEvent and DoubleClick? For example, on DoubleClick, switch color between red and blue, for a single click switch between yellow and purple.

2. You do not need interactor_style = interactor.CustomInteractorStyle(). This is created by ShowManager and if you want to access it, you just need to do showm.iren. This will avoid your error

3. showm.iren.add_callback (cube, ...)

nice progress!

[Nibba2018]

Hello @skoudoro , I tried showm.iren.add_callback(...) but it gives me an Attribute Error

Traceback (most recent call last):
  File "double_click.py", line 13, in <module>
    showm.iren.add_callback(cube, "LeftButtonPressEvent", change_color)
AttributeError: 'vtkRenderingOpenGL2Python.vtkXRenderWindowInteract' object has no attribute 'add_callback'

[skoudoro]

I tried showm.iren.add_callback(...) but it gives me an Attribute Error

ok, need to check, maybe it is showm.style.add_callback instead

[Nibba2018]

Hello @skoudoro , I am successfully able to detect and differentiate between single clicks & double clicks. But I am unable to understand how to abort or stop the propagation of the previously initiated single click event. Can you give me some idea where I should look for a solution... Thank you.

[Nibba2018]

Also, is the line self.AddObserver("LeftButtonDoubleClickEvent", self._process_event) sufficient enough to create a new event for double click? or do I need to do something else?

[skoudoro]

Hello @skoudoro , I am successfully able to detect and differentiate between single clicks & double clicks. But I am unable to understand how to abort or stop the propagation of the previously initiated single click event. Can you give me some idea where I should look for a solution... Thank you.

Hi @Nibba2018, That's good news! To stop the propagation,you need to use self.event.abort().
But, to use this method at the right place can be tricky, I need to go deeper into it.

Also, is the line self.AddObserver("LeftButtonDoubleClickEvent", self._process_event) sufficient enough to create a new event for double click? or do I need to do something else?

No, it is not because this custom event is never invoked. We need to create a custom event named LeftButtonDoubleClickEvent and then invoke it on our interactor. You will have to look at VTK examples to see how to manage a new custom event.

[Nibba2018]

Hello @skoudoro , I did some research and have come up with the following conclusions:

• The custom event can be implemented by subclassing vtkCommand.
• I was also able to find an example related to vtkCommand, but I am not sure how it works or how it is being implemented. I will be looking into it further.
• I also found some contradictions regarding subclassing vtkCommand here, but I am not sure whether it's outdated or not.

I will try implementing vtkCommand subclasses and see if it works.

[skoudoro]

Hi @Nibba2018,

Thank you for your research and all this information. You should look at this nice example too.
Basically, it seems that you need to follow this step:

1. create DoubleClickEvent in the init of our custom interactor style : self.DoubleClickEvent = vtk.vtkCommand.UserEvent+1
2. invoke this event on the leftclick fonction when you detect it: self.invokeEvent(self.DoubleClickEvent, 'DoubleClickEvent')
3. connect DoubleClickEvent with your double click function.

Does it make sense?

[Nibba2018]

Thank you @skoudoro , It makes it very clear. I will implement this right away.

[Nibba2018]

@skoudoro I am using this following for testing:

from fury import actor, window, interactor
import numpy as np

cube = actor.cube(np.random.rand(1, 3), np.random.rand(1,3), (1,1,1), heights=np.random.rand(5))

def single_click(iren, obj):
	print("Single Click")
	iren.force_render()

def double_click(iren, obj):
	print("Double Click")
	iren.force_render()

current_size = (800, 800)
showm = window.ShowManager(size=current_size, title="Double Click Test")
showm.scene.add(cube)
showm.style.add_callback(cube, "LeftButtonPressEvent", single_click)
showm.style.add_callback(cube, "DoubleClickEvent", double_click)
showm.start()

The changes are able to detect and differentiate clicks but is not able to propagate the Double Click Event Callback.

[Nibba2018]

@skoudoro , I ran the debugger and found that during single clicks, the control moves from self.propagate to prop.InvokeEvent and then to _add_callback function. But in the case of Double Clicks, the control doesn't go to _add_callback after the prop.InvokeEvent has been executed...

[skoudoro]

Interesting, I have no idea at this point, I need to go deeper.

Maybe @MarcCote have an idea about the DoubleClik

[skoudoro]

I suppose you are missing a self.InvokeEvent(...) to propagate the event to himself (the interactor)

prop.InvokeEvent propagates the event to all dependent actor

So you need both @Nibba2018

[Nibba2018]

@skoudoro , Initially I tried with self.InvokeEvent but it didn't work, so I thought I should be using prop.InvokeEvent instead as it was previously implemented in self.propagate_event.

This time I will try using both.

[MarcCote]

Hi @Nibba2018, thank you so much for taking a stab at this. Sorry for being late to the party. See my comments in the code to fix your double click issue.

On a side note, the expected behavior of a double click event is:

• Two consecutive clicks on the same object/prop within some time interval.

At the moment, I see that the second click has to be in some radius of the first one. What's the expected behavior when the two clicks are not on the same prop/object but still within the predefined radius?

Regarding the "within a time interval", I guess we can do it in another PR.

[Nibba2018]

Hello @MarcCote , thank you for the review I will apply the changes and will let you know if I have any questions.

[Nibba2018]

@MarcCote Thank you for the suggestions. The double click callback now triggers normally. Regarding the double click behavior, Yes it only detects double clicks if the second click is within a certain radius of the first click irrespective of the prop. I will add some changes to in order to detect whether the clicks are on the same prop or not.

[Nibba2018]

Hello @MarcCote , looks like single clicks arent working the way they are supposed to and hence causing tests to fail. Failed tests start from test_ui_line_slider_2d_horizontal_bottom.

[skoudoro]

Thank you for the rebase @Nibba2018.

Any additional comments? I will merge this by the end of the day.

[MarcCote]

LGTM

[skoudoro]

Thank you @MarcCote and @Nibba2018 for this nice work. merging