Question: How do I detect if the mouse is over any UI element? [UI Elements]

In the old Unity UI I would have
`EventSystem.current.IsPointerOverGameObject()`
and that would work in stuff like (pseudo code follows)
`getbuttondown("fire1") if ( EventSystem.current.IsPointerOverGameObject() ) } do nothing { else } `
Now im trying to switch to UIElements - which looks awesome - but I really need to be able to tell if the user is clicking on the UI or somewhere else. How do I do that? I could not find it in the docs

 

Do you want to know when the mouse enters and leaves the VisualElement, or when the MouseUpEvent/MouseDownEvents occur?

Depending on your need, one of these should do the trick:

Code (CSharp):

1. yourElement.RegisterCallback<MouseEnterEvent> ( x => OnMouseEnter ( x ) );
2. yourElement.RegisterCallback<MouseLeaveEvent> ( x => OnMouseLeave ( x ) );
3. yourElement.RegisterCallback<MouseUpEvent> ( x => OnMouseUp ( x ) );

 

This would work for a one-off, but what if you would want to do this for ALL of the elements, so essentially checking if the player is clicking a UI Element or trying to interact with the game?

 

What I did was create my own custom background element for each UI panel which goes over my game; those panels register/unregister themselves in a list of UI areas (via an interface). Then when my game gets a mouse click it runs through each of the areas to see if the mouse is in a UI area and, if so, it rejects the click and lets the UI Event system handle it. It's not pretty, particularly for panels which move or animate but, for my game, it got me the enough to replace the old "IsMouseOverUI" functionality.

Note: MouseEnterEvent and MouseLeaveEvent do not solve this problem because the mouse will "Leave" the background when it enters an interactable child element. Adding mouse enter/leave to 100s of elements in the UI is not really an option so rectangle testing it is.

 

I am at this point right now with 2021.1. Here you cannot click through from one ui document to another anymore, and also not on to UGUI.
The Sort order also works now with UGUI.

But I still don't see an option to detect if the mouse is over the UI without a detection-Panel which reacts to MouseEnter and MouseLeave.
And doing that with uitoolkit only can detect if the mouse is on that particular uidocument. If there are more layered this does not work.
What works is having a UGUI Canvas behind sorted behind all the UIToolkit-documents and detect there if the mouse is over the ui or not.
But this method has it's own problems because now, the detection-Panel blocks events.

Systems I knew solved this by raycasting and detecting if the raycast was blocked by the "UI" layer. This seems not possible with UIToolkit.

Or do I miss something important?

 

And it does not work in builds! My canvas UI detection mechanism works in the editor but not in build...

Edit:
Hm I have some other UGUI panels in front of that ui detector panel. It seams one of those panels blocks the detector in build but not in editor

 

Oh yes that works! Many thanks
I tried it before, but probably something else in my code broke it

 

@manuelgoellnitz Hi, bro, When I use "EventSystem.current.IsPointerOverGameObject()"，it always return false.
It is any trick for it?

 

EventSystem.current.IsPointerOverGameObject() return True for me, most of the time. UITK panel seems to not block the pointer being over GO, and also it seems it needs the EventSystem component, so when I use InputSystemEventSystem(UITookkit) component, there is a warning that only one event system can be active.

I found a solution in another thread yesterday. https://forum.unity.com/threads/using-new-input-system-with-ui-toolkit.1026847/

It's a hacky one, and one that probably requires you to use a single UI Document. I transitioned from using multiple UIDocs to a single one couple of weeks ago because of another problem, and I suggest this is the way you do it. If you do, then you can create a VisualElement master in your main Document and then place all your other UI inside the master. So then if you do (somewhere on Start or Awake) the following:

Code (CSharp):

1. MasterVisualElement.RegisterCallback<PointerOverEvent>((evt) =>
2.             {
3.                 OverUI = true;
4.             });
5.            
6.             MasterVisualElement.RegisterCallback<PointerOutEvent>((evt) =>
7.             {
8.                 OverUI = false;
9.             });

Where OverUI is some static bool, you are now able to check this bool and if it's true, exit from your other input operations. This would work the best if your UI is static on screen. Mine wasn't, so there were couple of problems with showing/hiding UI panels (for example an options menu).

I used to show/hide panels using style.opacity, because using Flex/None or transform.scale Vector3.Zero/One was causing the UI to lose some of the layout. But when using opacity, the UI is still there, so this hack won't work. I tried modifying the picking mode to Ignore along with hiding the panel, but that did not work either. I had to reposition the panel outside of screen (for example style.top = Screen.height * 2) for this to work.

It works, but it all seems so hacky and buggy for such a trivial thing and I can't wait for this to be fixed. Someone if reading this, please perhaps suggest some improvements.

 

Dion't use the EventSystem of UIToolkit but the Unity Standard one. And only have one EventSystem in the scene.

 

I also tried this solution. But it has one flaw: I didn't try "PointeroutEvent" but "PointerLeaveEvent". And That Event is not fired when the user has the app in Window mode and moves the mouse from a UI element outside of the Window.

 

OK, I have fixed my problem and shared why it always return false
1.You must add the Standard EventSystem as what @manuelgoellnitz suggested
2.Set the "PickingMode.Ignore" even thought the panel include nothing but itself. It will broke the mouse event.

FYI

 

Unity, is there an official solution to this?

Using Component/Event/EventSystem result on not being able to use Component/UIToolkit/InputSysteEventSystem (UI Toolkit) (Unity throw warning about there being two event systems). The controls does not work correctly if I do not use the UI Toolkit specific component. I could for example not drag a slider, only click to change its position. But not using EventSystem (non UI Toolkit) causes that one can not use EventSystem.current.IsPointerOverGameObject().

[Edit] I see that EventSystem.current.IsPointerOverGameObject(), and my Slider, works despite the warning of having two event systems in the scene. This feels all so messy but I guess it is what we have to live with while UIToolkit is in "preview".

Now to figure out why TwoPaneSplitView is causing pickingmode=ignored to be ... ignored.

 

I dunno if this is what ur looking for , but this one worked for me :

Code (CSharp):

1.         /// <summary>
2.         /// Is mouse inside the rect of a visual element ?
3.         /// </summary>
4.         /// <param name="pos">The world space position of the mouse (evt.position)</param>
5.         /// <returns></returns>
6.         private bool IsInsideElement(VisualElement v , Vector2 pos)
7.         {
8.                 return v.worldBound.Contains(pos);
9.         }
10.  

 

How can we check whether the mouse is over a specific element? I have an inventory and equipment UI, and I've been using worldBound.Contains for drag and drop functionality. However, when one UI is behind the other, I need a way of determining which is in front prior to checking whether the item being dragged overlaps with the slots.

 

This depends on your uxml structure , for example if u have something like
<parent>
<inventory>
<equipement>
</parent>

then u can just use inventoryVisualElement.parent.IndexOf(inventoryVisualElement) or equipementVisualElement.parent.IndexOf(equipementVisualElement) to get who's in front , if u want to change the order of who's in front you can use the BringToFront() and SendToBack() methods.

if your hierarchy is more complex then you'll need to find their common ancestor in the hiararchy (aka their first parent element) and under that -let's call it "A" , then you find out the closest distinct parent of each under "A" element.
then you use the index of those two to figure out who's in front

Hope this helps

 

Hey! That does help! However, how would you use that method if you had multiple UI Documents?

 

By UI Documents you mean mutliple EditorWindows ? cuz multiple UI Documents != multiple EditorWindowsv.
if you mean multiple editor windows open , then i would start with this (i am just suggesting here , this is just where i would start and not tested)
- first i would register them in a static list to keep a list of the opens windows.
- Use the "OnFocus" unity special method to shuffle the list according to their order on screen
- if that doesn't work , i would look into "GUI.depth" which shows the current window's depth (careful , this used IMGUI and no UI Toolkit , so make sure to use the IMGUIContainer thingy)
- every editorWindow has a "position" property , it's the window's top-left corner postion in screenSpace , the rest of the elements in the window are in "local space" of the window.
- so if i wanted to test if elements (A and B for example) are on different windows are overlapping , i would basically
do something like :
Vec2 A_pos_In_screenSpace = A_position_in_its_own_window_local_space => A_pos_in_screen_space (based on the window's pos)

Vec2 B_pos_In_screenSpace = B_position_in_its_own_window_local_space => B_pos_in_screen_space (based on the window's pos)

do the comparison now since they are in the same space.

some like that

 

Is it fixed now in preview.18?

 

Tested it again, while having both

Input System UI Input Module

and

Input System Event System (UI Toolkit)

enabled doesn't produce any warnings or errors,

EventSystem.current.IsPointerOverGameObject();

still throws an exception.

Is there still no way to detect pointer over UI Toolkit elements?

 

If I turn off UI Toolkit EventSystem, I receive the following exception every frame:

Code (CSharp):

1. InvalidOperationException: You are trying to read Input using the UnityEngine.Input class, but you have switched active Input handling to Input System package in Player Settings.
2. UnityEngine.UIElements.DefaultEventSystem+Input.GetAxisRaw (System.String axis) (at Library/PackageCache/com.unity.ui@1.0.0-preview.18/Core/DefaultEventSystem.cs:423)
3. UnityEngine.UIElements.DefaultEventSystem.GetRawMoveVector () (at Library/PackageCache/com.unity.ui@1.0.0-preview.18/Core/DefaultEventSystem.cs:332)
4. UnityEngine.UIElements.DefaultEventSystem.ShouldSendMoveFromInput () (at Library/PackageCache/com.unity.ui@1.0.0-preview.18/Core/DefaultEventSystem.cs:362)
5. UnityEngine.UIElements.DefaultEventSystem.SendInputEvents () (at Library/PackageCache/com.unity.ui@1.0.0-preview.18/Core/DefaultEventSystem.cs:117)
6. UnityEngine.UIElements.DefaultEventSystem.Update (UnityEngine.UIElements.DefaultEventSystem+UpdateMode updateMode) (at Library/PackageCache/com.unity.ui@1.0.0-preview.18/Core/DefaultEventSystem.cs:77)
7. UnityEngine.UIElements.UIElementsRuntimeUtility.UpdateRuntimePanels () (at Library/PackageCache/com.unity.ui@1.0.0-preview.18/Core/UIElementsRuntimeUtility.cs:214)
8. UnityEngine.UIElements.UIElementsRuntimeUtilityNative.UpdateRuntimePanels () (at /Users/bokken/buildslave/unity/build/Modules/UIElementsNative/UIElementsUtility.bindings.cs:26)
9.  

Edit:
Unity 2021.1.23f1,
UIToolkit 1.0.0-preview.18
Input System 1.1.1

 

Ok the difference was that I have previously disabled regular `Event System` script and enabled `Input System Event System (UI Toolkit)` to make UI Toolkit work woth Input System. After our discussion I disabled the UI Toolkit system and enabled `Input System UI Input Module (Script)` back. But I didn't enabled general Event System since I didn't think it was used at all without UGUI.

Now that I have enabled it, everything works, including `IsPointerOverGameObject()`. Thanks a lot!

 

I didn't manage to make it work with touch screen. I have added an IsPointerOverGameObject check on an Input Action handler, and now I receive the following warning:

Code (CSharp):

1. Calling IsPointerOverGameObject() from within event processing (such as from InputAction callbacks) will not work as expected; it will query UI state from the last frame
2. UnityEngine.EventSystems.EventSystem:IsPointerOverGameObject ()
3.  

On touch screen scene raycast is not prevented with this check.
I suppose that the issue is that last frame state on touch input is not relevant in the frame of PointerDown event, but I can't imagine another place to put the IsPointerOverGameObject() check. With touch input the PointerDown event is the first to appear so there's even no pointer movement to update the UI state before handling the click.

What is the recommended way to block raycasts with touch input then?

 

I tried the setting you mentioned, however it did not solve the issue. Also there's no issue with trackpad and mouse, only touchscreen is affected by inability to detect buttons with IsPointerOverGameObject(). I will research this issue more since I think it's an issue with logic in my code and IGUI buttons would not be detected as well.

 

I've found that even with a singular event system in the scene this can return as always true when you're hovering over *any* game object. I cannot find any solution that won't be hacky in some way (e.g. compare mouse position vector to point A and point B spanning the length of a UI to see if it's within that UI range) for what I'm trying to do in my CoH-style RTS.

I'm using 2021.3.6f1 as required by my university for unity projects, which is why I've posted here about this.

 

I hope Unity puts some effort into making this easier. Feels obtuse right now.

Feels like there is a really powerful platform here but it's a headache to work with. I don't even see the EventSystem in the 2022.2.x documents. Is the EventSystem deprecated?

 

It doesn't seem to be in 2021.3 either.

 

hi there, just wanted to know if it is done yet and how should it be used now?
i actually want button-clicks not to be translated into ar raycasts...