I am working on my first Windows 8 RT application and started with the sample grid application. My goal is to change the style of one of these grid items.
I have been able to 'find' this item by using this:
if (dataItem.UniqueId.StartsWith("Group-1-Item-1"))
Then I created this style in C# (just as an example);
Style style = new Style (typeof(SampleDataItem));
Thickness thick = new Thickness(4,4,4,4);
style.Setters.Add(new Setter(Border.BorderThicknessProperty, new Thickness(100)));
However, now I have to apply this style to the specific data item - I have tried a lot of things, but I don't take they make much sense now that I look at them.
The data template for the dataItems for the Grid App project template is found in StandardStyles.xaml, and is referred to by the key "Standard250x250ItemTemplate".
If the idea is to vary the styling based on the content of the item, one approach might be to use a Binding.Converter, as shown here, to convert the value of the content in question to the desired style or style property.
For example, If I wanted to make any items in the default Grid App template have a green background if the item number was less than or equal to 3, and red if it was higher than 3, I would create the following converter class (in my case, I just added the class to the GroupedItemsPage.xaml.cs, just before the GroupedItemsPage partial class):
// Custom class implements the IValueConverter interface.
public class StyleConverter : IValueConverter
{
#region IValueConverter Members
// Define the Convert method to change a title ending with > 3
// to a red background, otherwise, green.
public object Convert(object value, Type targetType,
object parameter, string language)
{
// The value parameter is the data from the source object.
string title = (string)value;
int lastNum = (int.Parse(title.Substring(title.Length - 1)));
if (lastNum > 3)
{
return "Red";
}
else
{
return "Green";
}
}
// ConvertBack is not implemented for a OneWay binding.
public object ConvertBack(object value, Type targetType,
object parameter, string language)
{
throw new NotImplementedException();
}
#endregion
}
Once the class is defined, along with the desired Convert method, I add an instance to it in my App.xaml file, so it will be available to the item template in StandardStyles.xaml:
<!-- Application-specific resources -->
<local:StyleConverter x:Key="StyleConverter"/>
In StandardStyles.xaml, I made a copy of the Standard250x250ItemTemplate that binds from the Title property of the item, to my converter class, like so:
<DataTemplate x:Key="Standard250x250ItemTemplate_Convert">
<Grid HorizontalAlignment="Left" Width="250" Height="250">
<Border Background="{Binding Title,
Converter={StaticResource StyleConverter}}">
</Border>
<StackPanel VerticalAlignment="Bottom"
Background="{StaticResource ListViewItemOverlayBackgroundThemeBrush}">
<TextBlock Text="{Binding Title}" Foreground="{StaticResource ListViewItemOverlayForegroundThemeBrush}" Style="{StaticResource TitleTextStyle}" Height="60" Margin="15,0,15,0"/>
<TextBlock Text="{Binding Subtitle}" Foreground="{StaticResource ListViewItemOverlaySecondaryForegroundThemeBrush}" Style="{StaticResource CaptionTextStyle}" TextWrapping="NoWrap" Margin="15,0,15,10"/>
</StackPanel>
</Grid>
</DataTemplate>
the key piece being the binding of the Border element's Background property to the Title, with the Converter={StaticResource StyleConverter}, which wires the item template up to my converter. Note that in addition to binding the Background property, I also removed the nested Image element from the original version of the item template.
Finally, in GroupedItemsPage.xaml, I change the item template to my customized version:
<!-- Horizontal scrolling grid used in most view states -->
<GridView
x:Name="itemGridView"
...
Padding="116,137,40,46"
ItemsSource="{Binding Source={StaticResource groupedItemsViewSource}}"
ItemTemplate="{StaticResource Standard250x250ItemTemplate_Convert}"
...
ItemClick="ItemView_ItemClick">
Once that's done, I can run the project, and here's what I see:
Hope that helps!
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Related
I have the following property in my ViewModel
public IEquipment Equipment
{
get
{
return equipment;
}
set
{
if (equipment != value)
{
equipment = value;
InvokePropertyChanged("Equipment");
}
}
}
This item itself has a bool property, which is bound to an Ellipse in my View, which I want to use as a indicator item:
<Ellipse Width="10" Height="10" Fill="{Binding Equipment.IsAvailable, Converter={StaticResource BoolToColorConverter}, FallbackValue=DarkGray}" Margin="1"/>
The BoolToColorConverter simply converts the color to either green (true) or red (false). During runtime Equipment can be an instance of one of two class types which inherit from IEquipment. Only one of them has the IsAvailable property. In practice this works fine, I get eighter my red or green color...or a gray one, in case the other type of equipment is active.
Problem is, that each time the GUI updates, the following warning gets output:
System.Windows.Data Warning: 40 : BindingExpression path error: 'IsAvailable' property not found on 'object'
How can I avoid this issue? Basically I want to bind to this property only if it is of the correct type.
I can think of two solutions, which I'm not particularly fond of:
Simply add the IsAvailable property to the other type and set it to null (BoolToColorConverter can handle null values and returns dark grey): This might be ok for a simple bool, but in my actual case there are other items, which are quite class specific.
Do the databinding in the code-behind: This might work. Using an event like Loaded on startup to set the binding manually at runtime based on the type. However, this might be troublesome for debugging later, because all other Bindings in the project happen directly in the xaml file. Additionally, Equipment might change during the lifetime of the ViewModel, so I would have to somehow track it.
Xaml doesn't bind to interfaces, it binds to concrete types.
If your types have different properties, then you need different xaml to bind them.
Use DataTemplates to specify different xaml for displaying each type.
If the properties on your derivatives of IEquipment (here Equipment and OtherEquipment as examples) differ a lot and do not share a common interface, they most likely differ in their appearance. In this case you would need different DataTemplates for each type. This is an example for a ContentControl, but it works the same fot ItemsContols with implicit data templates (no x:Key, but a DataType) that are applied automatically.
<ContentControl Content="{Binding Equipment}">
<ContentControl.Resources>
<DataTemplate DataType="{x:Type local:Equipment}">
<Ellipse Width="10" Height="10" Fill="{Binding IsAvailable, Converter={StaticResource BoolToColorConverter}, FallbackValue=DarkGray}" Margin="1"/>
</DataTemplate>
<DataTemplate DataType="{x:Type local:OtherEquipment}">
<Ellipse Width="10" Height="10" Fill="DarkGray" Margin="1"/>
</DataTemplate>
</ContentControl.Resources>
</ContentControl>
A workaround for your specific issue could be writing a custom, specialized value converter.
public class EquipmentAvailabilityToColorConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is Equipment equipment)
return equipment.IsAvailable ? Brushes.Green : Brushes.Red;
return (Brush)parameter;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new InvalidOperationException();
}
}
<Ellipse Width="10" Height="10" Fill="{Binding Equipment, Converter={StaticResource EquipmentAvailabilityToColorConverter}, ConverterParameter={x:Static Brushes.DarkGray}}" Margin="1"/>
I need to create a WPF ListBox that supports two features:
Content Converter Binding:
The items in the ListBox need to be passed to a converter that converts the items to a text format.
Display items in a way that lets users select and copy text from ListBox items
I need the text of each ListBox item to be selectable. Users want to use their mouse to drag-to-select parts of the elements so they can copy the text to their clipboard.
I implemented [this copy/paste solution][1] but it does not let a user select parts of the ListBox item text, rather it supports copying the entire text.
I'm able to create a ListBox using the converter, but I can not figure out how to put the converted text into a control that lets users select the displayed text. Here is what I have:
<ListBox Name="FinishedTestErrorsListBox"
FontSize="12"
ItemsSource="{Binding Path=SelectedComparisonResult.TestFailItems}">
<ListBox.ItemTemplate>
<DataTemplate>
<ContentControl Content="{Binding Converter={StaticResource testFailItemConverter}}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I've tried adding a TextBox to the DataTemplate as shown below...
<TextBlock Text="{Binding Converter={StaticResource testFailItemConverter}}"/>
... but this creates a runtime error caused by sending the wrong type of object to the converter. I know here I'm not setting up the converter binding properly, though I don't have a good grasp on how I should setup the binding here or why this causes errors.
So, my question is:
What content container can I use to let users select text from the individual ListBox items?
Thank you for any help,
Charlie
EDIT
Here's the converter code...
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
ITestFailItem i = (ITestFailItem)value;
return i.Itemize();
}
EDIT 2
The following runtime error is throw when the ListBox is first initialized:
An unhandled exception of type 'System.Windows.Markup.XamlParseException' occurred in PresentationFramework.dll
Additional information: Provide value on 'System.Windows.Baml2006.TypeConverterMarkupExtension' threw an exception
EDIT 3
The culprit is a line of code I'd omitted from the original snippet as I thought it was irrelevant - I've learned a good lesson along the way!
Extension Question
Why does the following snippet cause an error? How can I achieve the desired affect of making the textbox span the entire containing grid?
<TextBox Width="*"
Text="{Binding Path=., Converter={StaticResource testFailItemConverter}}"/>
Try this. TextBlocks don't support text selection, but TextBoxes do. You just have to make it read-only so the user can't modify the text, and change its border thickness and background so they look like labels:
<ListBox Name="FinishedTestErrorsListBox"
FontSize="12"
ItemsSource="{Binding Path=SelectedComparisonResult.TestFailItems}">
<ListBox.Resources>
<converter:TestFailItemConverter x:Key="testFailItemConverter" />
</ListBox.Resources>
<ListBox.ItemTemplate>
<DataTemplate>
<TextBox Text="{Binding Path=.,
Converter={StaticResource testFailItemConverter},
Mode=OneWay}"
BorderThickness="0"
Background="Transparent"
IsReadOnly="True"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Have You tried TextBox? You can select text inside textbox. Path have to be changed to Path=.
<TextBox Text="{Binding Path=., Converter={StaticResource testFailItemConverter}}" />
There is not much code to work with, but this code works for me:
xaml:
<Window x:Class="StackOverflowTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:s="clr-namespace:StackOverflowTest"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<s:TestFailItemConverter x:Key="testFailItemConverter" />
</Window.Resources>
<Grid>
<ListBox Name="FinishedTestErrorsListBox"
FontSize="12"
ItemsSource="{Binding Path=SelectedComparisonResult.TestFailItems}">
<ListBox.ItemTemplate>
<DataTemplate>
<!--<ContentControl Content="{Binding Converter={StaticResource testFailItemConverter}}"/>-->
<TextBox Text="{Binding Path=., Converter={StaticResource testFailItemConverter}}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Window>
Model's code:
public class Dummy
{
public ObservableCollection<string> TestFailItems { get; set; }
public Dummy()
{
TestFailItems = new ObservableCollection<string>(new List<string> { "a", "b" });
}
}
public class Model
{
public Dummy SelectedComparisonResult { get; set; }
public Model()
{
SelectedComparisonResult = new Dummy();
}
}
Converter's code:
public class TestFailItemConverter: IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return "aa";
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return value;
}
}
We're in the process of updating our gallery WPF application which contains our custom styled controls. The design is to have a toggle to show the XAML behind those custom controls, for easy reference and a guide for new colleagues.
The way I've currently implemented this is by creating two .xaml files, one containing just the controls, one with the controls and a textblock with the XAML coded used to implement those controls.
This is not something that's easily maintainable, since the quotes, >,< and other characters are not escaped in XAML strings. For reference this is what I have now in one of the 'Show code' views:
<TextBlock Visibility="Collapsed" Margin="5" Text="<controls:AutoCompleteTagBox
Name="AutoCompleteTagBoxWithStrings"
Margin="5"
ItemsSource="{Binding Names}"
FilterMode="Contains" />
<ListBox
ItemsSource="{Binding ElementName=AutoCompleteTagBoxWithStrings, Path=SelectedItems}"
Grid.Column="1"
BorderBrush="{StaticResource Blue}" BorderThickness="1" />"/>
As you can see, it doesn't look nice and once you update one of the controls you now have three places you need to change the XAML.
The next step is just to bind the TextBlock visibility and toggle it from 'Collapsed' to 'Visible'. But I want to know if there is a way to show the XAML in a textblock without having to hand write the string.
Thanks in advance for your advice!
Following from XAMIMAX's comment you could use an easy converter to save the xaml to a string using XamlWriter and strip the xmlns namespaces for brevity.
public class XamlConverter : IValueConverter
{
public readonly Regex xmlnsRegex = new Regex("xmlns=\".+\"");
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
var source = value as FrameworkElement;
if (source != null)
{
//Save xaml and strip xmlns namespaces
var xaml = xmlnsRegex.Replace(System.Windows.Markup.XamlWriter.Save(source), "");
return xaml;
}
return null;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
Example usage
<StackPanel>
<StackPanel.Resources>
<converters:XamlConverter x:Key="Converter_Xaml"/>
</StackPanel.Resources>
<Button x:Name="SourceButton" Content="Click Me" Margin="10"/>
<TextBlock Text="{Binding ElementName=SourceButton, Converter={StaticResource Converter_Xaml}}" TextWrapping="Wrap"/>
</StackPanel>
I have a longlistselector for my windows phone 8 app:
<phone:LongListSelector x:Name="AppMenuList" Background="Transparent"
ItemTemplate="{StaticResource AppMenuListTemplate}"
IsGroupingEnabled="true" HideEmptyGroups="true"
LayoutMode="List" SelectionChanged="OnMenuItemTapped"
Margin="5,50,0,0"/>
With the following DataTemplate:
<phone:PhoneApplicationPage.Resources>
<DataTemplate x:Key="AppMenuListTemplate">
<Grid>
<StackPanel Orientation="Horizontal" Margin="0,5,0,0" Height="80" Width="800" Tap="vTapFeedback">
<TextBlock HorizontalAlignment="Left" Margin="0,20,0,20" Height="50"
Width="800" TextWrapping="NoWrap"
Text="{Binding MenuItemName}" VerticalAlignment="Center"
FontSize="32" Foreground="#115445" />
</StackPanel>
</Grid>
</DataTemplate>
</phone:PhoneApplicationPage.Resources>
From my C# code, I am setting the ItemsSource property for the longlistselector to display the list of items to the user. However all the items are of same color as specified in the TextBlock property Foreground.
I have a requirement in which I want the user to be able to tap every item of the list and perform some operation except the one. I want that it should be shown as disabled to the user by using a Gray color for it.
I am not able to accomplish this. Can anyone suggest how I can do this ?
There are three solutions that come to my mind:
you can use VisualTreeHelper to find your textbox and then change its Foreground Color
I've bound Foreground color to a property of Item Class, then when I change this property, Foreground changes automatically. I assume than you were able to bind your Text, then there should be no problem with binding Foreground. One thing you will probably need is a Converter.
you can define VisualStates in Style of your TextBlock.
EDIT - code sample after request
I've definded my Converter like this:
namespace myApp.Converters
{
public class BoolToBrush : IValueConverter
{
private Brush FalseValue = (Application.Current.Resources["TransparentBrush"] as Brush);
private Brush TrueValue = (Application.Current.Resources["PhoneAccentBrush"] as Brush);
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value == null)
return FalseValue;
else
return (bool)value ? TrueValue : FalseValue;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return value != null ? value.Equals(TrueValue) : false;
}
}
In my Item class I've a property Selected (bool in this case) to which Foreground (or Background) is bound. I use it in XAML (item or control) like this:
<UserControl.Resources xmlns:local="clr-namespace:myApp.Converters">
<local:BoolToBrush x:Key="boolToBrush"/>
</UserControl.Resources>
<Grid Name="myElement" Background="{Binding Path=Selected, Converter={StaticResource boolToBrush}}">
Of course you can define more coplex convertes - if you need more Brushes and so on.
On the other hand I would also consider using VisualStates.
Hope this helps a little.
I have a ListBox on a WPF User Control that is defined as
<ListBox Grid.Row="1" ScrollViewer.CanContentScroll="False" Background="#00000000" BorderThickness="0" ItemsSource="{Binding BuyItNowOptions}"
ItemTemplate="{DynamicResource BuyItNowDataTemplate}" IsSynchronizedWithCurrentItem="True"
Style="{DynamicResource InheritEmptyListStyle}" SelectedItem="{Binding SelectedResearch}" ItemContainerStyle="{DynamicResource ListBoxItemStyle}"/>
BuyItNowOptions is a public property on the ViewModel that is of type ObservableCollection
In the BuyItNowDataTemplate I have a label that needs to have some logic performed before displaying a price.
<Label Padding="1" HorizontalContentAlignment="Stretch" Grid.Column="2" Grid.Row="2" Margin="1">
<TextBlock Text="{Binding ExchangePrice, StringFormat=C}"
Visibility="{Binding ReturnRequired, Converter={StaticResource BooleanToVisibilityConverter}}"/>
</Label>
The binding here indicates that it will use the ExchangePrice property of the instance of AutoResearchProxy that it is on like BuyItNowOptions[CurrentIndex].ExchangePrice.
What I would like to know is it possible to create the binding in such a way that it references the whole instance of the AutoResearchProxy so that I can pass it to a converter and manipulate several properties of the AutoResearchProxy and return a calculated price?
I would envision my converter looking like this.
public class PriceConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value is AutoResearchProxy)
{
var research = value as AutoResearchProxy;
//Some logic to figure out actual price
}
else
return String.Empty;
}
Hopefully this makes sense.
You can pass the whole datacontext-object to a Binding by not specifying a Path or by setting it to ., that however will result in the binding not updating if any of the relevant properties of that object change.
I would recommend you use a MultiBinding instead, that way you can target the necessary properties and the binding will update if any of those change. (For usage examples see the respective section on MSDN)
MyProperty="{Binding Converter={StaticResource ObjectToDerivedValueConverter}
That should do it.