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Windows Phone Image Binding
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Closed 10 years ago.
Is it possible to bind a collection of images AND change their Canvas.Left and Canvas.Top properties? I know how to bind them to a ListBox, however, I wish to change their location and have the images scattered about.
The following code sends the data to a ListBox and renders the images one after the other in a list effect - of course.
I am unable to use Canvas.Left/Top properties as obviously the images are in a List Box.
XML
<ListBox x:Name="listBoxItems">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Margin="5">
<Image Source="{Binding ImageUri}" Stretch="None" />
<TextBlock Text="{Binding Room.Items.ImageUri}"></TextBlock>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
C#
_roomView = new RoomViewModel();
_roomView.Room = new Room
{
Items = new List<Item> {
new Item {ImageUri = "/Escape;component/Images/Items/a.jpg"},
new Item {ImageUri = "/Escape;component/Images/Items/b.png"},
new Item {ImageUri = "/Escape;component/Images/Items/b.png"}}
};
listBoxItems.ItemsSource = _roomView.Room.Items;
Does anyone know how I can achieve this?
If you use in the ItemTemplate Canvas insteed of the StackPanel you can use the AttachedProperty: Canvas.Top/Canvas.Left on the Image and on the TextBlock too. With that you can set the positions of the items as you wish. I hope it could help you.
Related
I was solving Windows Phone 8.1 ListView wobbling problem and had code like below, however, once I add the ItemTemplate, the contents of the List cannot be seen, I'm wondering why and how to fix the problem.
<ListView
Grid.Row="1"
x:Name="ListViewEvents"
Loaded="OnListViewEventsLoaded"
ItemsSource="{Binding xx}"
ItemTemplateSelector="{StaticResource xx}"
ItemContainerStyle="{StaticResource xx}"
IsItemClickEnabled="True">
<ListView.ItemTemplate >
<DataTemplate >
<Grid Width="{Binding ActualWidth, ElementName=EventsListGrid}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Your Width binding is trying to read the ActualWidth property of an element in your XAML named EventsListGrid, but there's no such element in the sample code you've provided. As such, the binding engine is unable to set the Width property on your grid, most likely setting it to some unset/NaN value. At least I can confirm this when setting up a similar case as the one you provided and inspecting in Snoop the ListViewItem containers generated for each item in the test collection bound to the ListView. Perhaps you want to set the element name to ListViewEvents in this case or some other parent element not shown in the example?
I need to format the text in each textblock, which is an item of my ListBox. I have managed to make something but it doesnt look the same as if I would call the Console.WriteLine-Method.
private void addNewGameItem(string gamename, string lastChangedDate)
{
ListBoxItem lbi = new ListBoxItem();
StackPanel stpl = new StackPanel();
TextBlock tbl = new TextBlock();
tbl.Text = String.Format("{0,-100} {1,30}", gamename, lastChangedDate);
tbl.FontSize = textBlockFontsize;
stpl.Orientation = Orientation.Horizontal;
stpl.Children.Add(tbl);
lbi.Content = stpl;
savedGamesList.Items.Add(lbi);//Add the ListBoxItem to the ListBox
}
The problem is that if the gamename is longer than for example the previous one, the date will appear futher right. How can I format this, that it doesnt matter how long the gamename is, so the date-string will start on the same position, in each textblock?
This might be easier done in XAML rather than the code behind as you can more easily define the DataTemplate to be used to display your list items that way. Make your list of games an ObservableCollection and bind the ItemsSource of your list box to that. This will mean it auto-updates when you add a new item to the list.
Then you can split the string into two parts, one for the game name the other for the date:
<ListBoxItem ...>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding GameName}"/>
<TextBlock Text="{Binding LastChangedDate}"
HorizontalAlignment="Right"/>
</StackPanel>
</DataTemplate>
</ListBoxItem>
Then in the ListBox style definition include the line:
HorizontalContentAlignment="Stretch"
This will make each list box item fill the entire width of the list box and (as long as the dates are formatted so that they all come out the same length) align them correctly.
I've got a Grid which contains a TextBlock. The Grid's DataContext is of type List<MyClass>, and I'd like to bind the TextBlock.Text property to the MyClass.MyProperty property of first element in the List. I tried something like:
<Grid x:Name="RootLayout">
<TextBlock Text="{Binding [0].MyProperty}" />
</Grid>
But of course, that did not work. What's the right way of doing this?
Edit:
I'm going to try and make my explanation more clear. I've got multiple elements in the grid, each of which binds to a different item in the list. The items are laid out in a customized manner which cannot be accomplished by a GridView or ListBox. One of the items in the Grid is the TextBlock, and I'd like to bind its Text property to a property of the first element in the list. Once I know how to do that, I can extend that knowledge to add bindings to the rest of the elements in the grid.
Edit 2:
Turns out, my code works just fine in Silverlight. My project is actually a WinRT project, but I figured I'd get quicker answers if I tagged it as Silverlight, since databinding is supposed to work the same. I'm assuming this is a bug in WinRT, so I'll just have to find a workaround for it :(
I'm not sure I get why you want to do this, but you could create a property that returns what you want from the item in the list like so:
public string MyBindingProperty
{
get { return MyList != null && MyList.Count > 0 ? MyList[0].MyProperty : "Error Text"; }
}
Then you'd bind to MyBindingProperty:
<TextBlock Text="{Binding MyBindingProperty}" />
EDIT
I was wrong in saying you can't get at the items in the List - my bad. Your binding should look like this:
<TextBlock Text="{Binding [0].MyProperty}" />
If you need me I'll be in the corner enjoying my humble pie.
I am not an expert of SL but I think your are using the wrong Grid object; try with DataGrid in this way:
<data:DataGrid x:Name="targetDataGrid">
<data:DataGrid.Columns>
<data:DataGridTextColumn Header="MyProperty"
Binding="{Binding MyProperty}" />
</data:DataGrid.Columns>
</data:DataGrid>
also see here for more details: Defining Silverlight DataGrid Columns at Runtime
Edit: then go this way:
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0" Text="{Binding MyProperty}" />
</Grid>
found here: http://msdn.microsoft.com/en-us/library/cc278072%28v=VS.95%29.aspx scroll donw the article...
[Edit #3] - to anyone reading this question: do not under any circumstance use the approach outlined in this question. It is a Coding Horror. I freely admit this, knowing that all programmers have worked themselves into a corner in the past, and (especially when learning a new technology) we all have been led astray by other, well-meaning developers on the interweb. Read the answer by Robert first, then read this question. Please.
[Edit #2b]
I apologize for the length of this question - there is a question in here (at the end!), but I wanted to make sure the source code was explicit. Anyway.
[Edit #2] - question title changed to more accurately reflect the... question.
[Edit] - I've updated some more of the history as to how I ended up at the design / code that I did here: Obligatory Blog Post. If it helps clarify the question below, feel free to read it...
Original question
The application I'm working on uses Prism and WPF, with a number of modules (currently 3), one of which hosts the application menu. Originally, the menu was static with hooks into CompositeCommand / DelegateCommands, which worked great for routing button presses to the appropriate presenter. Each MenuItem used a StackPanel in its header to display the content as a combination of an image and a text label - which was the look I was going for:
<Menu Height="48" Margin="5,0,5,0" Name="MainMenu" VerticalAlignment="Top" Background="Transparent">
<MenuItem Name="MenuFile" AutomationProperties.AutomationId="File">
<MenuItem.Header>
<StackPanel>
<Image Height="24" VerticalAlignment="Center" Source="../Resources/066.png"/>
<ContentPresenter Content="Main"/>
</StackPanel>
</MenuItem.Header>
<MenuItem AutomationProperties.AutomationId="FileExit" Command="{x:Static local:ToolBarCommands.FileExit}">
<MenuItem.Header>
<StackPanel>
<Image Height="24" VerticalAlignment="Center" Source="../Resources/002.png"/>
<ContentPresenter Content="Exit"/>
</StackPanel>
</MenuItem.Header>
</MenuItem>
</MenuItem>
<MenuItem Name="MenuHelp" AutomationProperties.AutomationId="Help" Command="{x:Static local:ToolBarCommands.Help}">
<MenuItem.Header>
<StackPanel>
<Image Height="24" VerticalAlignment="Center" Source="../Resources/152.png"/>
<ContentPresenter Content="Help"/>
</StackPanel>
</MenuItem.Header>
</MenuItem>
</Menu>
Unfortunately, the application has gotten a bit more complex and it is desireable to have other modules register themselves with the menu - hence, I've been looking at making the menu dynamic. The goal is to have other modules (through a service) be able to add commands to the menu at will - for example, Module A will add a menu item in the Toolbar module that calls a handler in Module A. There's a few excellent articles out there on this subject - the two I've looked at are Building a Databound WPF Menu Using a HierarchicalDataTemplate and WPF Sample Series - Databound HierarchicalDataTemplate Menu Sample. Following the advice in the article, I have managed to make a dynamically constructed menu with no obvious data binding problems - it can create a menu with items linked backed to my presentation model, reflecting the structure of an ObservableCollection in the presentation model
Currently, my XAML looks like the following:
<UserControl x:Class="Modules.ToolBar.Views.ToolBarView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:model="clr-namespace:Modules.ToolBar.PresentationModels"
xmlns:local="clr-namespace:Modules.ToolBar">
<UserControl.Resources>
<model:ToolBarPresentationModel x:Key="modelData" />
<HierarchicalDataTemplate DataType="{x:Type model:ToolbarObject}"
ItemsSource="{Binding Path=Children}">
<ContentPresenter Content="{Binding Path=Name}"
Loaded="ContentPresenter_Loaded"
RecognizesAccessKey="True"/>
</HierarchicalDataTemplate>
</UserControl.Resources>
<UserControl.DataContext>
<Binding Source="{StaticResource modelData}"/>
</UserControl.DataContext>
<Menu Height="48" Margin="5,0,5,0" Name="MainMenu" VerticalAlignment="Top" Background="Transparent"
ItemsSource="{Binding}">
</Menu>
</Grid>
</UserControl>
The code behind for the view does the heavy lifting in the ContentPresenter_Loaded method:
private void ContentPresenter_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
ContentPresenter presenter = sender as ContentPresenter;
if (sender != null)
{
DependencyObject parentObject = VisualTreeHelper.GetParent(presenter);
bool bContinue = true;
while (bContinue
|| parentObject == null)
{
if (parentObject is MenuItem)
bContinue = false;
else
parentObject = VisualTreeHelper.GetParent(parentObject);
}
var menuItem = parentObject as MenuItem;
if (menuItem != null)
{
ToolbarObject toolbarObject = menuItem.DataContext as ToolbarObject;
StackPanel panel = new StackPanel();
if (!String.IsNullOrEmpty(toolbarObject.ImageLocation))
{
Image image = new Image();
image.Height = 24;
image.VerticalAlignment = System.Windows.VerticalAlignment.Center;
Binding sourceBinding = new Binding("ImageLocation");
sourceBinding.Mode = BindingMode.TwoWay;
sourceBinding.Source = toolbarObject;
image.SetBinding(Image.SourceProperty, sourceBinding);
panel.Children.Add(image);
}
ContentPresenter contentPresenter = new ContentPresenter();
Binding contentBinding = new Binding("Name");
contentBinding.Mode = BindingMode.TwoWay;
contentBinding.Source = toolbarObject;
contentPresenter.SetBinding(ContentPresenter.ContentProperty, contentBinding);
panel.Children.Add(contentPresenter);
menuItem.Header = panel;
Binding commandBinding = new Binding("Command");
commandBinding.Mode = BindingMode.TwoWay;
commandBinding.Source = toolbarObject;
menuItem.SetBinding(MenuItem.CommandProperty, commandBinding);
}
}
}
As you can see, I'm attempting to recreate the StackPanel / Image / Name combination of the original menu, just doing so in the code behind. Attempting to do this has not worked out so well - while the menu objects are certainly being created, they don't "appear" as anything other than blank, clickable objects - the StackPanel, Image, Name, etc. aren't being rendered. Interestingly enough, it also is causing the original text in the ContentPresent in the HierarchicalDataTemplate to be erased.
The question then, is there a way to set a MenuItem's Header property in the Load event such that it will display on the UserControl properly? Is the fact that the items in the header are not being displayed indicative of a DataBinding problem? If so, what would be the proper way to bind the Header to a transient object (the StackPanel that was created in the load event handler)?
I'm open to changing anything in the code above - this is all sort of prototyping along, trying to figure out the best way to handle dynamic menu creation.
Thanks!
I'll confess that I haven't dug quite as deep into your example as maybe I should, but whenever I see code-behind that's searching the visual tree, I think, could this be handled more explicitly in a view model?
It seems to me in this case that you could come up with a pretty straightforward view model - an object exposing Text, Image, Command, and Children properties, for instance - and then create a simple data template that for presenting it as a MenuItem. Then anything that needs to alter the contents of your menus manipulates this model.
Edit:
Having looked at what you're up to in more detail, and the two examples you've linked to in your blog post, I am banging my head against the desk. Both of those developers appear to be under the misapprehension that the way to set properties on the menu items that are being generated by the template is to search through the visual tree in the ContentPresenter.Load event after they're created. Not so. That's is what the ItemContainerStyle is for.
If you use that, it's quite straightforward to create dynamic menus of the type you're describing. You need a MenuItemViewModel class that has INotifyPropertyChanged implemented and exposes these public properties:
string Text
Uri ImageSource
ICommand Command
ObservableCollection<MenuItemViewModel> Children
Using this:
<Menu DockPanel.Dock="Top" ItemsSource="{DynamicResource Menu}"/>
where the ItemsSource is an ObservableCollection<MenuItemViewModel>, and using this template:
<HierarchicalDataTemplate DataType="{x:Type local:MenuItemViewModel}"
ItemsSource="{Binding Path=Children}">
<HierarchicalDataTemplate.ItemContainerStyle>
<Style TargetType="MenuItem">
<Setter Property="Command"
Value="{Binding Command}" />
</Style>
</HierarchicalDataTemplate.ItemContainerStyle>
<StackPanel Orientation="Horizontal">
<Image Source="{Binding ImageSource}" />
<Label Content="{Binding Text}" />
</StackPanel>
</HierarchicalDataTemplate>
the menus in the window exactly represent what's in the collection, and are dynamically updated as items are added and removed, both to the top-level items and to the descendants.
There's no clambering about in the visual tree, no manual creation of objects, no code-behind (other than in the view model, and in whatever populates the collection in the first place).
I've built a pretty thoroughly worked example of this; you can download the project here.
Another possible approach could be having the Menu be a region and agree on a convention so all views added to that region have a ViewModel with a property named MenuHeader. That way, the region adapter can simply get the menu header from the View's Data Context, and set it to the item when adding it.
Something similar is done in Prism with views added to a Tab Region. You can read more here.
I hope this provides some useful guidance.
Thanks,
Damian
I want to populate a TreeView with UserControls, but I only want the Name property to show up, not the entire UserControl. The following code gives me weird crashes as soon as I add something to myUCs:
C#:
var myUCs = new ObservableCollection<UserControl>();
MyTreeView.ItemsSource = myUCs;
XAML:
<controls:TreeView x:Name="MyTreeView">
<controls:TreeView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</controls:TreeView.ItemTemplate>
</controls:TreeView>
Does anyone know how to use a list of UserControls as an ItemSource for TreeViews?
I found one not so convenient workaround: instead of a List of UserControls, use a Dictionary, and change the XAML to:
<controls:TreeView x:Name="MyTreeView">
<controls:TreeView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Key.Name}"/>
</DataTemplate>
</controls:TreeView.ItemTemplate>
</controls:TreeView>
The same bug(?) exists in ListBox, a solution is provided here:
Use UIElements as ItemsSource of ListBox in Silverlight
That particular fix does not work for TreeView
You may have to create your own class that extends UserControl and override the ToString() method so that it returns the name property.