I have a Windows 8.1 application with a GridView bound to a custom (sortable, deduplicated) observable collection. In this collection, I do some heavy filtering and setting an IsHidden flag for every item.
In the data template for the item, there is a condition making the item collapsed if IsHidden flag is set to true.
<Grid Width="160" Height="280" Visibility="{Binding IsHidden, Converter={StaticResource InvertedBooleanToVisibilityConverter}}">
This approach works in Windows Phone 8.1 XAML, making the items disappear from the ListView but it does not work in Windows 8.1 GridView. The problem with Windows 8.1 is that when I set an item in the collection to hidden, id disappears from the GridView but leaves an empty place, so there is a gap in the GridView.
Any ideas on how to solve it? Maybe same XAML style editing?
Here is a minimal solution to reproduce the problem: https://dl.dropboxusercontent.com/u/73642/gv.zip
I tried binding width and height of the items to the hidden flag and setting it to 0 when the item is hidden, but it did not help, still a gap in the GridView.
Update: One workaround would be filtering the actual bound collection, but this is not possible, because of some business requirements.
The problem is in the GridView's ItemsPanel.
Both ItemsWrapGrid and WrapGrid are uniform grids. All their child elements will be sharing the same height and width. That's why even if you collapse the ItemTemplate, the space is still reserved.
What you really need here is a WrapPanel. WINRT doesn't have a built-in WrapPanel but Jerry Nixon has built one and you can grab it from here.
After you updated your GridViews ItemsPanel, you still have one more thing to do. You need to also get the GridViewItem that hosts your Itemtemplate and set its Visibility to Collapsed.
private async void Button_Click(object sender, RoutedEventArgs e)
{
ds[5].IsHidden = true;
await Task.Delay(1000);
var gridViewItem =(GridViewItem)this.gv.ContainerFromIndex(5);
gridViewItem.Visibility = Visibility.Collapsed;
}
I put a little delay above to make the collapsing more obvious.
I tried your sample solution and changed it to a ListView instead. It exhibits the same behavior when the grid itself is hidden. I don't have XAML Spy to verify, but it appears that any List based control will allocate a rendered item for each item in the list.
I changed your click handlder to instead ds.RemoveAt(5); instead of hiding the item, and the element is removed from view with a nice animation. This appears to be as expected, and an interesting find.
It takes me a lot of time to understand the problem, and the solution right in front of my eyes. You trying to hide the item itself but the container still there, When you add an item to an GridView, the item is wrapped in an item container. from msdn :
" When you add an item to an ItemsControl, the item is wrapped in an
item container. For example, an item added to a ListView is wrapped in
a ListViewItem. Without UI virtualization, the entire data set is kept
in memory and an item container is also created for each item in the
data set. A ListView that's bound to a collection of 1000 items will
also create 1000 ListViewItem containers that are stored in memory."
You need to disable the container and create two DataTemplate and using DataTemplateSelector you can choose which DataTemplate for disable and active items. Check this useful article .
Related
I'm not being able to update a single item's DataTemplate on a list during runtime. In detail, here is what I'm trying to accomplish.
I have a Listbox where the items can have different states (Collapsed, expanded, disabled, etc), each with a different layout. I'm using a TemplateSelector to choose the correct DataTemplate according to a property on my class and that's working all great when I first create the list, the items are shown properly. However, when I change the property that sets the DataTemplate in runtime, the NotifyPropertyChanged is called and the information of the item is updated on the list, but not the DataTemplate. For example: I have a collapsed item with a label X that i want to expand. I click on the item and the label changes to Y but the DataTemplate doesn't update.
Any idea on how I can do this? Can't the DataTemplate be updated during runtime unless it is for the whole list?
I'll appreciate any help.
Make UserControl and use it inside your data template. Now, to change the state you can call methods on this UserControl and it will update. You can use animations via storyboard too.
I'm developing windows metro app. In my application, I've one Listview with wrapgrid in itemspanel to display list of items on vertical rows with specific height. I want to display one item on top of the first column of list view, which shows result/stats of list items.
I would like to know if it is possible without adding custom item to datasource of listview?
ListView has a Header property in which you can Place content before the ListViews Items.
As commented, I've implemented following solution which is not elegant but worked for me.
Use Datasource converter to add dummy item in main list. So, my original list remains as is.
Use Template Selector to bind different template for first item.
Handle Selection and clicked event of dummy item.
I have a simple combobox bound to a List where A has a property Key and a property Value.
The combobox binds fine and works except for one flaw. It has a large empty space at the bottom where there are no items (i.e they don't get highlighted on hover or any such thing, there are no extra items, it is just that there is an empty space). How can I get rid of it?
http://i.stack.imgur.com/2yN9r.jpg
This is most-probably because of the template of the ComboBox under your current theme. Try changing Windows theme to Aero or Luna (seems like now you have it set to Classic).
If that's the issue, then there's a way to "fix" it by using a custom template, but then you break consistency from user's point of view. You'd need to take it into consideration.
you need to change the Template of combobox and reset the popup height acordingly. check below.
http://msdn.microsoft.com/en-in/library/ms752094%28v=vs.85%29.aspx
Search for popup under the tempalte and add the minheight=0 into it.
In my ComboBox ItemsSource="{Binding MyItems..., if MyItems is a List, it will leave extra space. if MyItems is an ObservableCollection, the extra space goes away. This may due to a Microsoft bug that ItemsSource was not properly notify by MyItems change when it is a List object.
I am running into an issue where i am using a panorama control and binding it to a datasource. But i still do want other custom items on another panorama items where i need a textblock, a grid and so on. So if i am adding it in the backend it doesnt show up those panorama items. It just shows the datasource binded items. Why is that so? Both of them should work out.
Can anybody help me with a solution for this.
Thank You.
Since you're wanting to manually add PanoramaItems, I can think of two approaches:
Make sure your Panorama.ItemsSource is set to an ObservableCollection that is accessible in the code behind or viewmodel, and then add your new items to that ObservableCollection which should update the Panorama.
Don't databind the Panorama control's Items - just add items manually when you want them.
Either way, the Panorama's ItemTemplate gets evaluated when the items are added to the underlying collection, so using a DataTemplateSelector will allow your code to determine which DataTemplate to apply when the new item is added without affecting the templates for previous items.
/chris
I just built a WPF form that contains a ListBox. The ListBox has bound to it a list of TextBox controls. I need to make each TextBox control a TabStop so that a user can hit tab, type in a number, hit tab again and type in the next number, etc.
Problem is, the ListBox itself catches the tab then the next tab skips to following control after the ListBox.
Is there a way to make each TextBox inside the ListBox be tabbable (or perhaps another type of databound control that would work)?
Thanks
Well we don't really have enough information to answer the question (this depends on what Templates and Style the ListBox is using) but you'll potentially need to play with the KeyboardNavigation.TabNavigation property to change how to cycle through the items and set IsTabStop on the ListBox to false.
Something like:
<ListBox DataSource={Binding} IsTabStop="False" KeyboardNavigation.TabNavigation="Cycle" />