Hello Teodosia,

thanks for your quick response. In fact I can reproduce the issue with your attached project without having to introduce a true custom class.

The issue is actually not a broken UI but broken UI automation. UI Automation is what tools like TestComplete and others are using to run automated UI tests. I could verify the issue using the Inspect tool from the windows SDK (for example here: C:\Program Files (x86)\Windows Kits\10\bin\<version>\x64\inspect.exe).

The first screenshot shows the output of the Inspect tool when the creation filter is active:

My focus is on the Monday item of the drop down and the Inspect tool shows that this item is offscreen, thus it is not showing a highlight to indicate that the item is accessible for UI automation.

In a next step I commented out the creation filter and get this situation:

Here the monday item has a highlight and the offscreen property is set to false. 

As I have mentioned above I assume the bounds of the Accessibility object of these ValueListItemUIElements are not properly initialized - but I have no clue how I would do this.

BTW, one modification I had to make to your project was to use Infragistics 11.2 because that's the version we are still on. Other than that your code is unmodified.

Thanks in advance for your help in this matter.

Best regards

Uwe

Hello,

After an investigation and discussing the described issue with our developers I could say that UIAutomation is basing IsOffScreen on the position of the UIElement for the item, and so the CreationFilter is moving or removing the UIElement and the control is therefore unable to determine the correct IsOffScreen value.

In your case, the CreationFilter is replacing the existing ValueListItemUIElement for every ValueListItem with a new ValueListItemUIElement. So the original ValueListItemUIElement that the ValueListItem is referencing is no longer parented to the control. So that affects the IsOffScreen because it's like the ValueListItem has no visual representation.

If you need to do something with the CreationFilter, then it should be modifying the existing elements, not removing and replacing them like in your case. The best suggestion is not using CreationFilter at all. In case you do not require some items to be in the list you could implement some logic that does not add such elements depending on some condition to the list. In case you want to hide some row another approach would be to use UltraDropDown.

However, we don't actually support UIAutomation for Accessibility. Our UIA implement is only intended for CodedUITests and it might be better just to turn off support for UIA. There's a static property that could be used:

UltraControlsBase.UIAutomationForCodedUITestingEnabled = false;

Let me know if I may be of any further assistance.

Sincerely,

Teodosia Hristodorova

Associate Software Developer

Hi - unfortunately modifying properties will not help. I had to override a method of ValueListItemUIElement to avoid exceptions that occur sporadically when hovering over a ValueListItem through an overlaid WPF window (very hard to reproduce - that's why I didn't even try to put it into this forum). My solution successfully avoids this problem - but introduces this UIAutomation problem.

Just for your info my class looks like this:

    public class SafeValueListItemUIElement: ValueListItemUIElement
    {
        /// <inheritdoc />
        public SafeValueListItemUIElement(
            ValueListItemContainerUIElement parent, 
            ValueListItem valueListItem, 
            bool isMruItem, 
            int listIndex)
            : base(parent, valueListItem, isMruItem, listIndex)
        {
        }

        /// <inheritdoc />
        protected override void InitAppearance(ref AppearanceData appearance, ref AppearancePropFlags requestedProps)
        {
            try
            {
                base.InitAppearance(ref appearance, ref requestedProps);
            }
            catch (NullReferenceException e)
            {
                TraceUI.Log.Error($"NullReferenceException in InitAppearance of {nameof(SafeValueListItemUIElement)}: {e}");
            }
        }

        /// <inheritdoc />
        protected override bool WantsMouseHoverNotification => false;
    }

Again, I cannot avoid these exceptions by modifying any properties of the existing ValueListItem instances.

And from your statement I understand that you do not support UI automation (or just specific flavors of it - I didn't completely understand the distinction you are trying to make).

Looks like I'm stuck again.

Out of curiosity, does the IsOffScreen property work correctly when you are NOT using the CreationFilter? I can't find anything in our code that would support this property for a ValueListItem either way.

My initial assumption here was that the ValueListItem is storing it's ValueListItemUIElement and since that element is no longer associated with the ValueListItem, since you removed it, that it thinks it's off-screen. But I took another look and that's not the case. the ValueListUIElement actually handles most of the accessibility funcitonality, and it does have a reference back to the ValueListItem, so I don't see why the IsOffScreen would suddenly not work due to the creation filter. 

I suspect the CreationFilter has nothing to do with it, and the IsOffScreen property doesn't work simply because it's not implement for UI. 

So did you try this?

UltraControlsBase.UIAutomationForCodedUITestingEnabled = false;

This will turn off UIA support, which is only for CodedUITests, anyway, and fall back to MSAA support, which is the older-style Accessibility model.

Hi Mike - without the creation filter this is working - see my second post with the screen shots. I didn't try yet to disable UIAutomation for CodedUI since our approach to UI automation worked so far without having to set this property. It's really just the element that is replaced through the creation filter that has this issue.

As I have written in my first post for some reason the AccessibilityInstance after replacing the UIElements has a zero BoundingRectangle (0,0,0,0) - I assume that means that all hit tests are failing.

I just checked with our dev lead for UI automation and he said that we are actually using UIA and that Windows maps UIA for controls that do not support this to MSAA. So switching off UIA is not really something we want to do. IsOffScreen is actually an UIA property.

Yes - makes sense. And it's easy to do. I just added it to the sample program and it works as expected.

One thing you might consider is what to do if the cache gets too big. That could happen, in theory, if you created a lot of new ValueListItems, either in a bunch of different ValueLists, or maybe because you ended up re-creating them for some reason. 

It might not be a terrible idea to trap the grid's CellListDropDown event and call a method on the CreationFilter that clears the cached every time the ValueList drops down - just to be safe. 

I don't think you did  - I added tracepoints in my test program and can see that items are created only once and then retrieved when the dropdown is expanded again.

Since the dictionary takes a ValueListItem as a key there shouldn't be an issue with multiple drop downs in the same grid. And the creation filter is per grid instance i.e. multiple grids in an application should not be an issue either.

Looks like this time it's really solved. This issue took me through some ups and downs. I hope this time we can stay on the up level (for a while at least).

Thanks again for your continued help and perseverance in this matter!

Yes, I see my mistake there. Sorry about that. 

This doesn't work because by the time AfterCreateChildElements has fired, the parent element is throwing away the existing MyValueListItemUIElement, and putting a regular ValueListItemUIElement in it's place. So your creation filter ends up swapping them out again. The code I put in to find an existing one never finds it, because it's already been removed. 

So I think we can get around this by caching the MyValueListItemUIElements in the CreationFilter. 

    public class ValueItemsCreationFilter : IUIElementCreationFilter
    {
        private Dictionary<ValueListItem, MyValueListItemUIElement> myValueListItemUIElements = new Dictionary<ValueListItem, MyValueListItemUIElement>();

        public void AfterCreateChildElements(UIElement parent)
        {
            if (parent is ValueListItemContainerUIElement)
            {                
                for (int i = parent.ChildElements.Count - 1; i >= 0; i--)
                {
                    var valueListItemUIElement = parent.ChildElements[i] as ValueListItemUIElement;
                    if (valueListItemUIElement != null &&
                        !(valueListItemUIElement is MyValueListItemUIElement))
                    {
                        // Try to find an existing MyValueListItemUIElement and re-use it if possible.
                        var valueListItem = valueListItemUIElement.ValueListItem;                        
                        MyValueListItemUIElement newValueListItemUIElement;
                        bool success = this.myValueListItemUIElements.TryGetValue(valueListItem, out newValueListItemUIElement);
                        if (!success)
                        {
                            newValueListItemUIElement = new MyValueListItemUIElement(
                                           parent as ValueListItemContainerUIElement,
                                           valueListItem,
                                           valueListItemUIElement.IsMruItem,
                                           valueListItemUIElement.ListIndex)
                            {
                                Rect = valueListItemUIElement.Rect
                            };

                            parent.ChildElements.RemoveAt(i);
                            parent.ChildElements.Insert(i, newValueListItemUIElement);
                            myValueListItemUIElements[valueListItem] = newValueListItemUIElement;
                        }
                        else
                        {
                            newValueListItemUIElement.Initialize(
                                valueListItem,
                                valueListItemUIElement.IsMruItem,
                                valueListItemUIElement.ListIndex
                                );
                        }
                    }
                }
                //parent.DirtyChildElements(true);
                var height = parent.ChildElements.Count * parent.ChildElements[0].Rect.Height;
                parent.Rect = new Rectangle(parent.Rect.X, parent.Rect.Y, parent.Rect.Width, height);
            }
        }

        public bool BeforeCreateChildElements(UIElement parent)
        {
            return false;
        }
    }

This seems to work - it only replaces the elements the first time you drop down the list and then doesn't replace them again while the dropdown is open. Unless I made some other logical error.

Hi Mike - while I confirmed that your code fixes the automation it will not fix my problem because it effectively NEVER replaces the UIItems with the subclassed ones because of an error in the logic in your code. With your code my debugger never breaks in the section where you create a new instance. So the behavior is like the creation filter didn't exist. I think the code should look like this instead:

...

                        // Try to find an existing MyValueListItemUIElement and re-use it if possible.
                        MyValueListItemUIElement newValueListItemUIElement = parent.GetDescendant(typeof(MyValueListItemUIElement), valueListItemUIElement.ValueListItem) as MyValueListItemUIElement;
                        
                        // only create new UI item if we didn't find a subclassed one
                        if (newValueListItemUIElement == null)                            
                        {
                            newValueListItemUIElement = new MyValueListItemUIElement(
                                           parent as ValueListItemContainerUIElement,
                                           valueListItemUIElement.ValueListItem,
                                           valueListItemUIElement.IsMruItem,
                                           valueListItemUIElement.ListIndex)
                            {
                                Rect = valueListItemUIElement.Rect
                            };
                        }

                        // replace with existing or new ui item
                        parent.ChildElements.RemoveAt(i);
                        parent.ChildElements.Insert(i, newValueListItemUIElement);


...

However, once I come back to actually replacing the items IU automation no longer works (i.e. Inspect no longer highlights the items in the drop down). So it looks like the journey is not yet over ...