I'm using XAML for a windows phone apps, and I'm binding a collection to graph control within the listbox Itemtemplate. Everything shows correctly except that the Horizontal axis is scaled per the data in the grid and I want them all scaled the same.
I've worked out the Maximum value - which need to establish the data binding - as its in a listbox itemtemplate I can't simply set the value in code. And for the data binding I only seem to see the elements in the collection but the value I have is not an element of the collection.
Is it possible to bind to a property/field of the page - that way I can set the value and all the grids can just bind to this property/fields.
One possible way to bind element inside ListBox item template to property of the page is by using ElementName binding. Simply name the page, then you can set binding source by page name, for example :
<phone:PhoneApplicationPage
..........
..........
x:Name="myPage">
<Grid x:Name="LayoutRoot" Background="Transparent">
<TextBlock Text="{Binding ElementName=myPage, Path=Name}" />
</Grid>
</phone:PhoneApplicationPage>
Above sample will display text "myPage" in the TextBlock. That way of binding also works for elements inside DataTemplate for ListBox item.
Related
This question is related to MVVM project structure.
For displaying data in a ListView I use a DataTemplate. The ItemsSource for the ListView is an ObservableCollection(of Person). Nothing special so far.
But in the DataTemplate I want to display a the State property of each Person in a ComboBox, where the actual value is displayed, and the user can choose another State.
The State comes from States, that is an ObservableCollection(of State).
In order to show all the States, I need to Bind the DataContext to the "toplevel" of the ViewModel. But how do I come down to the individual person again, that is shown in the DataTemplate? Or do I need another approach for this problem?
In XAML I have this:
<ComboBox DataContext="{Binding DataContext, ElementName=pageRoot}" ItemsSource="{Binding States}" DisplayMemberPath="Description" SelectedValue="{Binding ??????}" SelectedValuePath="ID" />
My question is: what do I need to set in order to Bind the SelectedValue correctly so that it shows the actual State per Person in the text-field of the Combobox?
Got it!
For the ItemsSource of the ComboBox I need the "higher" level of the DataContext hierarchy. Instead of Binding the entire ComboBox to that DataContext, I only needed to Bind the ItemsSource to that level.
The corrected code now looks like so:
<ComboBox
ItemsSource="{Binding DataContext.States, ElementName=pageRoot}"
DisplayMemberPath="Description"
SelectedValue="{Binding State.ID, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
SelectedValuePath="ID"
Trial and error works out! :-)
I have a Silverlight application and I use MVVM.
I would like to display or hide a TextBlock, based on another element current width (or window width at least...). The problem is that I currently have 2 texts on each other if I reduce the width of my window so I need want to hide the second textblock in that case...
I'm a beginner and I know how to use a VisibilityConverter with a boolean from my ViewModel, but not like this...
To bind to a property of another element, you would do something like this:
Visibility="{Binding ActualWidth,
ElementName=TheThingWhoseWidthYouAreBindingTo,
Converter={StaticResource WidthToVisibilityConverter}}"
And then create yourself a WidthToVisibilityConverter that takes the width value and returns a Visibility value.
I am developing a windows 8 app. And I want to display a GridView inside of another GridView item template. And I have added a visibility binding to the inner GridView, but the binding doesn't work when wrapping the GridViewItems in the outer GridView. It works when i use a simple ListView or GridView without any wrapping.
This is the main GridView with wrapping
<GridView
Name="feedGridView"
Background="Transparent"
SelectionMode="None"
ItemTemplate="{StaticResource MyFeedGridView}">
<GridView.ItemsPanel>
<ItemsPanelTemplate>
<VariableSizedWrapGrid Height="600" Orientation="Vertical" />
</ItemsPanelTemplate>
</GridView.ItemsPanel>
</GridView>
The style for "MyFeedGridView" which contains another GridView
<DataTemplate x:Key="MyFeedGridView">
<Grid HorizontalAlignment="Left" Width="500">
<StackPanel x:Name="gridViewStackPanel" Orientation="Horizontal" >
<GridView
HorizontalAlignment="Right"
x:Name="myFeedGridViewInListView"
ItemTemplate="{StaticResource MyFeedGridViewInListView}"
ItemsSource="{Binding listContent}"
Height="100"
Visibility="{Binding listContent,Converter={StaticResource FeedListToVisibilityConverter}}"
SelectionMode="None"
Width="400" />
</StackPanel>
</Grid>
</DataTemplate>
I am using a converter to hide or show the inner GridView. The below is the converter that i am using
public object Convert(object value, Type targetType, object parameter, string language)
{
List<ContentList> contents = value as List<ContentList>;
return (contents != null && contents.Count > 0) ? Visibility.Visible : Visibility.Collapsed;
}
My problem is that the inner GridView gets hidden for all the items or gets visible for all the items irrespective of the listcontent that I have bound.
I have noticed is that this is happening only when I set the ItemsPanel. If I remove the VariableSizedWrapGrid property then it's working as expected. But I need to wrap the items after each column so I can't do away with it.
Please let me know if you have any clue why this is happening.
Thanks
EDIT:
Attaching image of how the grid view items should be arranged. If you see the first item of the grid view, it has another grid view inside the grid view item representing songs. So this inner grid view will be empty for some items and populated for some. So I had written a visibility converter to show and hide the inner grid view. And when am using the converter,if the first grid view item has inner grid view items(songs then it will show inner grid view for all the items and if the first grid view item doesnt have any inner grid view items(songs) then it hides inner grid view for all the main grid view items.
Let me know if its not clear.
The problem with a GridView is that it uses the same size for all its GridViewItems by default. You can use a VariableSizedWrapGrid as its ItemsPanel, but that will disable virtualization and so you won't be able to use your GridView with a large number of items (more than a few dozen) without incurring performance cost.
For your scenario you could use a GridView with a non-uniform ItemsSource - one where some items represent the main list item and some that represent lists of songs and use the ItemTemplateSelector to specify which template to use for which type of item. It's not ideal of course, but this is what your easiest option is. One problem is that some of these song lists might end up orphaned in a different column than the item they are associated with, so for the ugly workaround you might need to figure out the number of items per column and in the list also include empty items or rearrange the items so that the empty-end-of-column items are filled with items that don't have any song lists associated with them.
A better option might be to use a VariableSizedWrapGrid as ItemsSource or simply use a manually populated Grid and add a more... item at the end that opens a ListView, since vertical lists IMHO are easier to scroll than horizontal GridViews. You would still need to use a non-uniform ItemsSource and ItemTemplateSelector to get the desired layout and keep virtualization of the list, but that's what you get.
Sorry if title is weird , because the problem itself is kinda weird.
I have a TextBlock and Slider Control on Clientside.
The Slider is {Binding} to Textblock.
This is the code for them -
<TextBlock Text="{Binding Value}" x:Name="Name1Value" FontSize="25"/>
<Slider ValueChanged="slider_ValueChanged_1" x:Name="slidervalve" Value= "{Binding ElementName=Name1Value,Path=Text}" StepFrequency="25" />
Now when Slider Value changes,Slider calls a method slider_ValueChanged_1,which sends its value to server. The server accepts the value and sends the new value back to client and this new value from server is set to the textblock( x:Name="Name1Value") through an observablecollection with inotifypropertychanged implemented. The slider is {Binding} to textblock.
1)Now the first time i change the value on slider on client, the server accepts the new value and returns the new value and i am setting the new value to textblock.
2)Now i am changing the value on server and the value is correctly updated in textblock and then the slider value changes to textblock value.
3) now after this first cycle,if i change the value on server again ,the textblock on client is getting updated but the slider does not change to textblock value.
But the slider is bound to textblock. How can i solve this?
Edit1: FYI , the textblock and the slider are in same page but in different stackpanels
A Slider control's Value property is of type double, while TextBlock.Text is a string. Binding these two together without a converter is asking for trouble. You should bind your Slider.Value to the DataContext/view model and typically make sure the binding Mode=TwoWay.
I am trying to bind a list of objects to a list control for a Windows Phone 8 app which also contains another list within it. I have tried to find out how to set this out so that when selecting an item from the parent list the child list is then loaded into a separate list control but cannot find any details. Any help would be most appreciated as I have hit a dead end with this.
I am trying to use lists as below:
List which then contains a List which also contains a List. I need to setup an initial list of stations which the user will select one, which will then populate another list with the platforms, and then selecting a platform will load the list of trains.
You should bind your outermost list to the outermost listbox (or whatever list control you are using).
After that you can bind the selecteditem of the outerlist to the child listviews.
Here's an example:
<ListBox ItemsSource="{Binding OuterList}" x:Name="OuterList" SelectionMode="Single" />
<ListBox ItemsSource="{Binding ElementName=OuterList, Path=SelectedItem}" x:Name="Innerlist1" />
<ListBox ItemsSource="{Binding ElementName=InnerList1, Path=SelectedItem}" />