如何从ListView中的模板数据中获取UIElement？

Question

Okay, i feel slightly dumb for askin this but, I have a listview with a templated class MyClass or whatever, whenever i "myListView.Add(new MyClass())" the winrt platform adds a new UIElement there and binds the proper properties into their proper uielements properly, now, I want to be able to iterate through these logical items (myListView.Items or myListView.SelectedItems) and get their corresponding UIElement for animation, is that possible?

like for example

class PhoneBookEntry {
    public String Name { get;set }
    public String Phone { get;set }
    public PhoneBookEntry(String name, String phone) {
        Name = name; Phone = phone;
    }
};

myListView.Add(new PhoneBookEntry("Schwarzeneger", "123412341234");
myListView.Add(new PhoneBookEntry("Stallone", "432143214321");
myListView.Add(new PhoneBookEntry("Statham", "567856785678");
myListView.Add(new PhoneBookEntry("Norris", "666666666666");

And in XAML (just an example so i can explain what I mean)

<ListView.ItemTemplate>
     <DataTemplate>
         <Grid>
              <TextBlock Text="{Binding Name}"/>
              <TextBlock Text="{Binding Phone}"/>
         </Grid>
     </DataTemplate>
</ListView.ItemTemplate>

So, my point and objective here is to

foreach(PhoneBookEntry pbe in myListView.Items) // or SelectedItems 
{
    UIElement el; // How can I get the UIElement associated to this PhoneBookEntry pbe?
    if(el.Projection == null)
        el.Projection = new PlaneProjection;
    PlaneProjection pp = el.Projection as PlaneProjection;
    // Animation code goes here.
    if(myListView.SelectedItems.Contains(pbe)
        //something for selected
    else
        //something for not selected
}

I just need a way to get an UIElement which is being used to represent this logical data class PhoneBookEntry in the templated listview. Also, this necessity comes with a very big problem I'm having where, selected items doesn't differ visually on Windows Phone -_- any ideas?

Answer 1

Ok I may look like a fool answering my own question but i've figured a way out.

First things first: ListViews only create UIElements for determinate items in the list (the ones cached and the ones being shown). So if you do add 2000 items to myListView.Items, the effective ammount of UIElements representing these items will be 56 or close number. Because, the ItemListView simulates the UIElements even if they're not there, just to give size and position to the scrollbar (hence why scrolling down on very large lists cause some lag, WinRT is unloading UIElements and loading new ones)

From that, I figured out I could simply iterate through the current list of loaded UIElements through

// For each of the cached elements
foreach(LIstViewItem lvi in myListView.ItemsPanelRoot.Children) 
{
    // Inside here I can get the base object used to fill the data template using:
    PhoneBookEntry pbe = lvi.Content as PhoneBookEntry;
    if(pbe.Name == "Norris")
        BeAfraid();
    // Or check if this ListViewItem is or not selected:
    bool isLviSelected = lvi.IsSelected;
    // Or, like I wanted to, get an UIElement to animate projection
    UIElement el = lvi as UIElement;
    if(el.Projection == null)
        el.Projection = new PlaneProjection();
    PlaneProjection pp = el.Projection as PlaneProjection;
    // Now I can use pp to rotate, move and whatever with this UIElement.
}

So, this is it. Right beneath my nose...

Answer 2

您还可以使用ListView.ContainerFromItem或ListView.ContainerFromIndex方法，这将返回列表视图中给定项目的容器UI元素（当然，仅当生成容器时）