如何使用鼠标单击获取ListView（GridView）单元格的内容

Question

I am trying to get the text value of a "cell" inside of a GridView that is set as the view of a ListView. I do not want to get the SelectedItem of the ListView as that just returns my entire View Model (but not which property the cell refers to).

I am able to get the text value by responding to direct mouse events (up down or whatever) and if the value is a textblock, obviously I can use the text. This works great and as of right now this is my only solution, although its currently limited.

I would like to take it a step further and be able to click anywhere with in the cell area, navigate around to find the appropriate textblock and then use that value. I have tried a half million ways to do this but what seems logical doesn't seem to quite work out like it should.

Setup:

I have a dynamic GridView that creates its own columns and bindings based on data models that I pass to it. I am using a programmatic cell template (shown below) to have individual control over the cells, particularly so I can add a "border" to it making it actually separate out each cell. I have named the objects so I can access them easier when I'm navigating around the VisualTree.

Here is the Template Code. (Note that the content presenter originally was a textblock itself, but this was changed for later flexibility)

private DataTemplate GetCellTemplate(string bindingName)
    {
        StringBuilder builder = new StringBuilder();
        builder.Append("<DataTemplate ");
        builder.Append("xmlns='http://schemas.microsoft.com/winfx/");
        builder.Append("2006/xaml/presentation' ");
        builder.Append("xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' ");
        builder.Append("xmlns:local = 'clr-namespace:XXXXXXXX");
        builder.Append(";assembly=XXXXXXXXX'>");
        builder.Append("<Border Name=\"border\" BorderThickness=\"1,0,0,0\" BorderBrush=\"Gray\" Margin=\"-6,-3,-6,-3\">");
        builder.Append("<Grid Margin=\"6,3,6,3\">");
        builder.Append("<ContentPresenter Name=\"content\" HorizontalAlignment=\"Stretch\" Content=\"{Binding ");
        builder.Append(string.Format("{0}", bindingName));
        builder.Append("}\"/>");
        builder.Append("</Grid>");
        builder.Append("</Border>");
        builder.Append("</DataTemplate>");
        DataTemplate cellTemplate= (DataTemplate)XamlReader.Parse(builder.ToString());
        return cellTemplate; 
    }

What I have Tried:

The logical approach for me was to react to a Mouse event. From the object that had the mouse event I would do either A. Look at its children to find a textblock, or B. Get its parent then look for child with a textblock.

My assumption is that if I click in white space I'm clicking in a container that has my textblock. So far the two things that come up are a Border and a Rectangle (if I don't click the text itself). A. Returns absolutely nothing except for the recangle and the border. When I do B i can find textblocks but they are every single text block in the entire row.

So what I try to do from that is get all textblocks, then go backwards till I find which one has a IsMouseOver property as true. It turns out none of these objects EVER have a IsMouseOver except the content presenter for the entire row. So this seems to indicate to me is that the whitespace in the cells does not actually contain the textblock.

What I find is that when I click on the Border and start looking at children, I eventually get to a container that has a rectangle (the rectangle I click) and a grid row view presenter. The presenter shows all of the objects inside the row (hence why i would get all textblocks when i do this recursive scan).

Here is some of the code used to do this to get an idea of what i'm doing. I have written about 10 different versions of this same recursive code generally attempting to find who has the Mouse over it and is related to a textbox.

private void OnPreviewMouseUp(object sender, MouseButtonEventArgs e)
    {
        object original = e.OriginalSource;
        if (original is TextBlock)
        {
            this.valueTextBlock.Text = ((TextBlock)original).Text;
        }
        else if (original is FrameworkElement)
        {
            var result = GetAllNestedChildren<Border>(VisualTreeHelper.GetParent((DependencyObject)original)).Where(x => x.Name == "border").Where(x => HasAChildWithMouse(x)).ToList();

        }
        else
        {
            this.valueTextBlock.Text = string.Empty;
        }
    }

    private bool HasAChildWithMouse(UIElement element)
    {
        if (element.IsMouseOver || element.IsMouseDirectlyOver)
            return true;
        var childCount = VisualTreeHelper.GetChildrenCount(element);
        for (int i = 0; i < childCount; ++i)
        {
            var child = VisualTreeHelper.GetChild(element, i);
            if (child is UIElement)
                if (HasAChildWithMouse((UIElement)child))
                    return true;
        }
        return false;
    }
private IEnumerable<T> GetAllNestedChildren<T>(DependencyObject obj) where T : UIElement
    {
        if (obj is T)
            yield return obj as T;
        var childCount = VisualTreeHelper.GetChildrenCount(obj);
        for (int i = 0; i < childCount; ++i)
        {
            var child = VisualTreeHelper.GetChild(obj, i);
            foreach (var nested in GetAllNestedChildren<T>(child))
                yield return nested; 
        }
    }

    private T GetObjectByTypeParentHasMouse<T>(DependencyObject obj) where T : UIElement
    {
        if (obj is T)
        {
            if ((VisualTreeHelper.GetParent(obj) as UIElement).IsMouseOver )
            {
                return obj as T;
            }
        }
        var childCount = VisualTreeHelper.GetChildrenCount(obj);
        for (int i = 0; i < childCount; ++i)
        {
            var child = VisualTreeHelper.GetChild(obj, i);
            var correctType = GetObjectByTypeParentHasMouse<T>(child);
            if (correctType != null)
                return correctType;
        }
        return null;
    }

    private T GetContainedType<T>(DependencyObject obj, bool checkForMouseOver) where T : UIElement 
    {
        if (obj is T && ((T)obj).IsMouseOver)
            return obj as T;
        var childCount = VisualTreeHelper.GetChildrenCount(obj);
        for (int i = 0; i < childCount; ++i)
        {
            var child = VisualTreeHelper.GetChild(obj, i);
            var correctType = GetContainedType<T>(child, checkForMouseOver);
            if (correctType != null)
                return correctType;
        }
        return null;
    }

The other approach I took was to start with the TextBlock itself, find its containing parent and find out how i can navigate to the answer. I find the templateparent is the ContentPresenter (named ="content") I find the grid, and then the border. The parent of the border is a content presenter whos content is the data view model for the entire row. The parent of this contentpresenter is the grid column's presenter. This is the same one that i was navigating up to in the other one.

It would appear that the first approach objects while are contain the cell do not actually contain the textblock or the entire cell templated items. It would appear to me there is no way to go from the Border or Rectangle that is clicked, back to the actual text field.

"Long story short" is there ANY way to make this connection?

(Btw I am not willing to give up this ListView/GridView because its payoffs far outweigh this negative and I'd gladly give up on this idea to keep the rest).

Answer 1

I think you sjould be able to either

1) Add some kind of (toggle)button to the root of your data template, and either bind to Command and handle it on your viewmodel or bind to IsChecked/IsPressed and handle changes via data triggers or w/e on the view side.

2) Add EventTrigger to your datatemplate at some point, and handle PreviewNouseUp/Down events there via simple animations.