I have a Listbox done like this
<ListBox x:Name="lbAlbumSelect">
<ListBox.ItemTemplate>
<DataTemplate>
<Button>
<Button.Content>
<StackPanel>
<Image />
<TextBlock TextWrapping="Wrap"
Text="{Binding album_name}" />
</StackPanel>
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I want to access every Image programmatically and set its Source. I tried to navigate the listbox like this
foreach (Button btn in lbAlbumSelect.Items)
{
StackPanel stack=btn.Content;
Image image=stack.Children.ElementAt(0) as Image;
//every ListBoxItem is binded to a clsAlbums object that contains various data,
//also the name of the image file, but not the path.
string pathImg = #"/Assets/Images/" + (btn.DataContext as clsAlbums).album_img;
LoadImage(pathImg, image); //function that sets image source to path img
}
But gives me a Invalid Cast Exception on the foreach clause.
Is there a faster and more correct way to do this?
You should ideally be binding the image source to the control. Add an additional property to your class clsAlbums which can be bound to the Image source.
public class clsAlbum
{
public string album_name { get; set; }
public string album_img { get; set; }
public string album_img_src
{
get
{
return #"/Assets/Images/" + album_img;
}
}
}
Now bind this additional property album_img_src to your xaml.
<ListBox x:Name="lbAlbumSelect">
<ListBox.ItemTemplate>
<DataTemplate>
<Button>
<Button.Content>
<StackPanel>
<Image Source="{Binding album_img_src}"/>
<TextBlock TextWrapping="Wrap"
Text="{Binding album_name}" />
</StackPanel>
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The item is actually ListBoxItem. In your case Button is content of ListBoxItem and Content of Button is StackPanel and Image is child of StackPanel. So you need to traverse visual tree somehow and you can do so using Linq to visual tree, for example. http://www.codeproject.com/Articles/63157/LINQ-to-Visual-Tree
Probably easiest way of accessing elements inside datatemplate is from it's loaded or initialized event:
here:
<Image Loaded="Image_Loaded" />
void Image_Loaded(object sender, EventArgs e){
var image =(Image)sender;
Try to avoid acessing elements inside datatemplates. 90% times you achieve your goal better, using ViewModel, converters, using behaviours, datatriggers or extracting datatemplate to separate UserControl
Related
I have an ObservableCollectiong<StringWrapper> (StringWrapper per this post) named Paragraphs bound to an ItemsControl whose ItemTemplate is just a TextBox bound to StringWrapper.Text.
XAML
<ItemsControl Name="icParagraphs" Grid.Column="1" Grid.Row="7" ItemsSource="{Binding Path=Paragraphs, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}}">
<ItemsControl.Template>
<ControlTemplate TargetType="ItemsControl">
<StackPanel Orientation="Vertical">
<ItemsPresenter />
</StackPanel>
</ControlTemplate>
</ItemsControl.Template>
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBox Name="tbParagraph" TextWrapping="Wrap" AcceptsReturn="False" Text="{Binding Path=Text}" Grid.Column="0" KeyUp="tbParagraph_KeyUp" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
C#
public class StringWrapper
{
public string Text { get; set; }
public StringWrapper()
{
Text = string.Empty;
}
public StringWrapper(string text)
{
Text = text;
}
}
I'm trying to make it so when I press enter in a TextBox, I insert a StringWrapper in my ObservableCollection after the StringWrapper bound to the TextBox that's currently focused, which generates a new TextBox. So far, my code does this, though there are a couple glitches to work out.
My question is, how do I then set the focus to the newly generated TextBox? As far as I can tell, the control generation happens after the function that inserts the string returns.
I looked for something like an ItemsControl.ItemsSourceChanged event, but, at least, that name doesn't exist. I also tried attaching a handler to ObservableCollection.CollectionChanged, but that too seemed to fire before the TextBox was generated. Last, since the ItemsControl.Template is a StackPanel, I looked for a StackPanel.ControlAdded event, but couldn't find that either.
Ideas? Thanks!
You may have to handle CollectionChanged and then schedule the focus action to occur in the future using Dispatcher.BeginInvoke with a priority of Loaded. That should give the ItemsControl an opportunity to generate a container and perform layout.
I've ran into a bit of a wall with being able to bind data of my custom object list to a ListBox in WPF.
This is the custom object:
public class FileItem
{
public string Name { get; set; }
public string Path { get; set; }
}
And this is the list:
private List<FileItem> folder = new List<FileItem>();
public List<FileItem> Folder { get { return folder; } }
The list gets populated and maintained by a FileSystemWatcher as files get moved around, deleted, renamed, etc. All the list does is keeps tracks of names and paths.
Here's what I have in the MainWindow code-behind file (it's hard coded for testing purposes for now):
FolderWatcher folder1 = new FolderWatcher();
folder1.Run(#"E:\MyApp\test", "*.txt");
listboxFolder1.ItemsSource = folder1.Folder;
Here's my XAML portion:
<ListBox x:Name="listboxFolder1" Grid.Row="1" BorderThickness="0"
ItemsSource="{Binding}"/>
Unfortunately, the only thing that gets displayed is MyApp.FileItem for every entry. How do I display the specific property such as name?
You will need to define the ItemTemplate for your ListBox
<ListBox x:Name="listboxFolder1" Grid.Row="1" BorderThickness="0"
ItemsSource="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The easiest way is to override ToString on your FileItem, (The listbox uses this to populate each entry)
public override string ToString()
{
return Name;
}
Each item in the list that ListBox shows automatically calls the ToString method to display it, and since you didn't override it, it displays the name of the type.
So, there are two things you can do here.
Override the ToString method like Sayse suggested.
Use DataTemplate and bind each of your properties seperatly
In your resource add the template with a key
<DataTemplate x:Key="fileItemTemplate">
<StackPanel>
<TextBlock Text="{Binding Name}"/>
<TextBlock Text="{Binding Path}"/>
</StackPanel>
</DataTemplate>
and give it as your listbox ItemTemplate
<ListBox x:Name="listboxFolder1" Grid.Row="1" BorderThickness="0" ItemsSource="{Binding}" ItemTemplate="{StaticResource fileItemTemplate}">
In case anyone comes across this now via search, I just encountered pretty much the same issue in a C# UWP app.
While the XAML bits in Nitin's answer above were necessary, they didn't fix the issue alone -- I also had to change my equivalent of Folder to be an ObservableCollection, rather than a List, to get the ListBox to show the property I needed.
OK, here's my issue :
I've got a custom class, with a list of items - each of which has an image path associated with it
I've added a folder WITH the images inside the project (so I suppose there are being added in the XAP too, huh?)
When I'm trying to bind the Source of an image item in XAML, it's not working.
<ListBox Margin="0,0,-12,0" ItemsSource="{Binding Items}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Margin="0,0,0,17">
<Image Height="100" Width="100" Margin="12,0,9,0" Source="/AlbumArt/{Binding AlbumArt}"/>
<StackPanel Width="311">
<TextBlock Text="{Binding Title}" TextWrapping="Wrap" Style="{StaticResource PhoneTextLargeStyle}"/>
<TextBlock Text="{Binding Author}" TextWrapping="Wrap" Margin="12,-6,12,0" Style="{StaticResource PhoneTextSubtleStyle}"/>
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
What am I doing wrong? Any ideas?
P.S.
I've also tried Source="{Binding AlbumArt}" but it's still not displaying anything.
The craziest thing is that, if I set the Source to a specific image (e.g. /AlbumArt/someImage.jpg), the image seem to work fine in Visual Studio & the Emulator.
I don't think Binding works that way. If it is not possible to prepend the string "/AlbumArt/" to your image path property (which is AlbumArt), I would suggest using a converter to do so.
Also, formatting strings only works when the target property is a string so StringFormat is out. Someone correct me if I'm wrong about StringFormat
If you have binding issues always check the output window for details. That is where information about binding errors is displayed.
This Source="/AlbumArt/{Binding AlbumArt}" won't work because it will just be treated as a string.
Without seeing your class it's hard to be certain but the property you're binding to ("AlbumArt") should be a Uri and not a string and it should be populated with a relative Uri to the image. That image should also be set to having the build action of Content.
what you have to is this..
<Image Height="100" Width="100" Margin="12,0,9,0" Source="{Binding ImagePath}"/>
as you said you have list of items( i think it would be class that also having paths of images ) so make this property in this class and for every item put the path in this property for coresponding item.
private string _ImagePath;
public string ImagePath
{
get
{
return _ImagePath;
}
set
{
_imagePath = value;
}
}
it would be better if you implement INotifyPropertyChanged in your item class.
How about getting more nesty.
private string _AlbumArt;
public string AlbumArt
{
get
{
return _AlbumArt;
}
set
{
if(_AlbumArt!=null)
_AlbumArt=#"/AlbumArt/"+ value;
}
}
and Binding
<Image Height="100" Width="100" Margin="12,0,9,0" Source="{Binding AlbumArt}"/>
I'm pretty sure you've just used the wrong path, try this one....
"/ApplicationName;component/AlbumArt/{Binding AlbumArt}"
Replace the ApplicationName section with your applications name of course. MAKE SURE TO REPLACE SPACES IN IT WITH %20
I have an app for windows 8 that needs to take a Json string and deseriaizes it into DATACONTRACTS and it will display the information I wish in a Listbox that will have a max height and will scroll if greater than the max height.
The problem that im having it not so much as not being able to do it but rather not knowing how to do it.
So far I can deserialize the Json and I can specify where I want each item to go into the UI but what im trying to do is basically a for each item in the array I want it to make a new Stackpanel formatted with Textblocks that will have the information from the Json. I don't know how to this unfortunately and I don't really know what im searching for to get tutorials on how to do it
This is the code I have that takes the items from the json with a helper class and puts them in the Text of the TextBlocks.
var _FilterSaleList = new FilterSalesList();
var _Sales = await _FilterSaleList.FindSalesbyFilters();
string _SaleName = _Sales.sales[0].name.ToString();
string _SaleDescription = _Sales.sales[0].description.ToString();
string _SaleName1 = _Sales.sales[1].name.ToString();
string _SaleDescription1 = _Sales.sales[1].description.ToString();
int _TotalResults = _Sales.sales.Length;
SaleTitle.Text = _SaleName;
SaleDescription.Text = _SaleDescription;
SaleTitle1.Text = _SaleName1;
SaleDescription1.Text = _SaleDescription1;
This is the XAML code for the Listbox with 2 Stack panels already in it.
<ListBox Grid.Row="1">
<StackPanel Margin="0,0,0,5">
<TextBlock x:Name="SaleTitle" Text="" HorizontalAlignment="Center" Margin="0,0,0,5"/>
<TextBlock x:Name="SaleDescription" Text="" HorizontalAlignment="Center" MaxHeight="40" Margin="0,0,0,5" TextWrapping="Wrap"/>
</StackPanel>
<StackPanel Margin="0,0,0,5">
<TextBlock x:Name="SaleTitle1" Text="" HorizontalAlignment="Center" Margin="0,0,0,5"/>
<TextBlock x:Name="SaleDescription1" Text="" HorizontalAlignment="Center" MaxHeight="40" Margin="0,0,0,5" TextWrapping="Wrap"/>
</StackPanel>
</ListBox>
Below is an image of how I would like it to look.
even though everything works this way like I said I would like it so that each item from the json will make a new stackpanel and display the information as in the image. I don't know what its called when this is done so even a simple hint as to where to look would be great!
http://puu.sh/2biMZ
In XAML there is a very nice feature called Binding, which allows you to simply bind an object or a list of objects to visual element. This way, you don't have to "build" the graphical user interface manually in C# code.
This is a very large topic, so you should probably have a look at what is MVVM, it will help you leverage the power of Binding : http://channel9.msdn.com/Series/Building-Apps-for-Both-Windows-8-and-Windows-Phone-8-Jump-Start/Building-Apps-for-Both-Windows-8-and-Windows-Phone-8-03-Model-View-ViewModel
But for now, what you could is :
1/ Define your ListBox as following, with a DataTemplate for the ItemTemplate property :
<ListBox Grid.Row="1" x:Name="SalesListbox">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Margin="0,0,0,5">
<TextBlock x:Name="SaleTitle" Text="{Binding name}" HorizontalAlignment="Center" Margin="0,0,0,5"/>
<TextBlock x:Name="SaleDescription" Text="{Binding description}" HorizontalAlignment="Center" MaxHeight="40" Margin="0,0,0,5" TextWrapping="Wrap"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The DataTemplate will tell how each item of the list should be rendered. You should also notice how we used Binding for the Text properties in each textblock. It's bound to name and description which are the name of the properties in your model.
And then you can populate your ListBox with your data :
var filterSaleList = new FilterSalesList();
var salesByFilters = await filterSaleList.FindSalesbyFilters();
SalesListbox.ItemsSource = salesByFilters.sales;
I need to display hierarchical data like:
public class Element
{
public string Name { get; private set; }
public Element[] Elements { get; private set; }
}
It would be just vertical panel with rectangle (with Name) for each element. If element is clicked, its child elements are displayed below it (element is expanded). If one of them is clicked, its elements appear and so on.
I already googled this and found out that there is no HierarchicalDataTemplate and no treeview in WinRT.
So I started to do it by myself.
I created ItemsControl and DataTemplate DataTemplate1 for it. In DataTemplate1 I also create ItemsControl and set DataTemplate2 as ItemTemplate. In DataTemplate2, ItemTemplate is DataTemplate3 and so on. The last DataTemplate is without ItemsControl.
In buttons Click event I change Elements IsVisible property for any elements in DataModel (that is Element[]), so it is easy to perform any custom logic to expand/collapse elements.
<DataTemplate x:Key="DataTemplate2">
<StackPanel Visibility="{Binding IsVisible, Converter={StaticResource BooleanToVisibilityConverter}}">
<Button Style="{StaticResource ItemButtonStyle}"
Click="MenuElement_Click">
<TextBlock Style="{StaticResource ItemTextBlockStyle}" Text="{Binding Name}"/>
</Button>
<ItemsControl ItemsSource="{Binding Elements}" ItemTemplate="{StaticResource DataTemplate3}"/>
</StackPanel>
</DataTemplate>
<DataTemplate x:Key="DataTemplate1">
<StackPanel Visibility="{Binding IsVisible, Converter={StaticResource BooleanToVisibilityConverter}}">
<Button Style="{StaticResource ItemButtonStyle}"
Click="MenuElement_Click">
<TextBlock Style="{StaticResource ItemTextBlockStyle}" Text="{Binding Name}"/>
</Button>
<ItemsControl ItemsSource="{Binding Elements}" ItemTemplate="{StaticResource DataTemplate2}"/>
</StackPanel>
</DataTemplate>
It works fine, but the problem is that if I want to enable 10 levels of hierarchy, I have to copypast 10 datatemplates. And 11 level still will not be available.
I also tried to create DataTemplate in C# and manually apply DataTemplate for its ItemSource and so on, in recursive method.
But I found 2 problems.
I don't know actually how to create DataTemplate in metro (C#), because it has no VisualTree property. I can only make (var dt= new Datatemplate();) and I don't know how to change it.
If I read DataTemplate from XAML (var dateTemplateRoot = (DataTemplate)this.Resources["DataTemplate1"];)
I still can't find ItemsControl in it and change its DataTemplate.
Actually, I can use var content = dateTemplateRoot.LoadContent(); and then find ItemsControl by VisualTreeHelper, but I can't use content after that as DataTemplate (content has type DependencyObject).
So, actually I have 2 questions.
Is it a good approach to perform hierarchical dropdown list by "binding" all items and only switch Visibility property?
The second is - how to enable unlimited level of hierarchical nesting?
WinRT XAML Toolkit has a TreeView control now. Check it out: http://winrtxamltoolkit.codeplex.com/SourceControl/changeset/view/b0ee76bd6492#WinRTXamlToolkit/Controls/TreeView/TreeView.cs
Take care though - this is just a rough port from Silverlight Toolkit and might not work so well. Also if you are planning on releasing it as part of a Windows Store application - you would need to heavily restyle it unless your app is desktop-only since it is not very touch-friendly.