Combobox "Select Item" binding - c#

I'm working on a few ComboBoxes that need a "select" property as the top option in WPF (c#)
At the moment I have the combobox's named and then populated in the code behind from a array string.
<ComboBox Width="150" x:Name="cmbTitle" Margin="3" SelectedIndex="0" />
.
cmbTitle.Items.Add("Select");
foreach (var title in Constants.Title)
cmbTitle.Items.Add(title);
My Issue is that the selectd Index will always be off by 1 of the index in the string.
After doing my research I see that this is a very prehistoric way of populating a combo box (WinFrom background). Constants seem to be stored in Enums in every example I have looked at so would like to move away from multiple string[]s.
What is my best way of binding an enum to a combobox while accommodating for a "select" option in WPF?
I've looked at half a dozen options today and I'm not too sure what other code examples to list.
It's quite a open question, but I'm quite lost.
Thanks in advance,
Oli

Values of an enumeration can be retrieved from Enum.GetValues(), and binding to a method is typically done using ObjectDataProvider. Here's an example of getting all BindingMode values:
<ObjectDataProvider x:Key="BindingModes" ObjectType="{x:Type sys:Enum}" MethodName="GetValues">
<ObjectDataProvider.MethodParameters>
<x:Type TypeName="BindingMode" />
</ObjectDataProvider.MethodParameters>
</ObjectDataProvider>
Now, we can bind ItemsSource of our ComboBox:
<ComboBox ItemsSource="{Binding Source={StaticResource BindingModes}}" />
Our control needs a new property for the prompt:
public class ExtendedComboBox : ComboBox
{
public static readonly DependencyProperty PromptProperty =
DependencyProperty.Register("Prompt", typeof(string), typeof(ExtendedComboBox), new PropertyMetadata(string.Empty));
public string Prompt
{
get { return (string)GetValue(PromptTextProperty); }
set { SetValue(PromptTextProperty, value); }
}
}
We can cheat a bit and place a TextBlock with the prompt inside our control, and hide it when there's an item selected. For this we rewrite ControlTemplate of the control with a new one containing the TextBlock. I modified template from there:
<Style x:Key="PromptTextBlock" TargetType="{x:Type TextBlock}" >
<Setter Property="Visibility" Value="Hidden" />
<Style.Triggers>
<DataTrigger Binding="{Binding SelectedItem, RelativeSource={RelativeSource TemplatedParent}}" Value="{x:Null}">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
<Style x:Key="PromptedComboBox" TargetType="{x:Type local:ExtendedComboBox}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:ExtendedComboBox}">
<Grid>
<ToggleButton x:Name="DropDownToggle"
HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
Margin="-1" HorizontalContentAlignment="Right"
IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}">
<Path x:Name="BtnArrow" Height="4" Width="8"
Stretch="Uniform" Margin="0,0,4,0" Fill="Black"
Data="F1 M 300,-190L 310,-190L 305,-183L 301,-190 Z " />
</ToggleButton>
<ContentPresenter x:Name="ContentPresenter" Margin="6,2,25,2"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}">
</ContentPresenter>
<TextBox x:Name="PART_EditableTextBox"
Style="{x:Null}"
Focusable="False"
Background="{TemplateBinding Background}"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Margin="3,3,23,3"
Visibility="Hidden"
IsReadOnly="{TemplateBinding IsReadOnly}"/>
<Popup x:Name="PART_Popup" IsOpen="{TemplateBinding IsDropDownOpen}">
<Border x:Name="PopupBorder"
HorizontalAlignment="Stretch" Height="Auto"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}"
BorderThickness="{TemplateBinding BorderThickness}"
BorderBrush="Black" Background="White" CornerRadius="3">
<ScrollViewer x:Name="ScrollViewer" BorderThickness="0" Padding="1">
<ItemsPresenter/>
</ScrollViewer>
</Border>
</Popup>
<TextBlock Margin="4,3,20,3" Text="{Binding PromptText, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource PromptTextBlock}"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Combining, we have:
<local:ExtendedComboBox Style="{StaticResource PromptedComboBox}" Prompt="Select an item" ItemsSource="{Binding Source={StaticResource BindingModes}}" />

I think the best way to populate your ComboBox will be using IDictionary.
As an example, your code-behind:
public YourEnum SelectedOption { get; set; }
public IDictionary<string, YourEnum> Options = new Dictionary<string, YourEnum?>();
Options.Add("Select", null);
Options.Add("Option 1", YourEnum.Option1);
...
Options.Add("Option N", YourEnum.OptionN);
Your xaml file:
<ComboBox ItemsSource="{Binding Options, ...}" SelectedValue="{Binding SelectedOption, ...}" DisplayMemberPath="Key" SelectedValuePath="Value" />

Related

Using three different ComboBoxItem styles in one WPF ComboBox

So I'm trying to create a user control for an application I'm working on. It's basically a ToggleButton next to a ComboBox. I was able to pretty much mock the ComboBox portion of the user control up in VS2015 the way the designers want it, but I feel like the way I'm going about it is not exactly the best way.
First, here is a link to a screenshot of what it looks like:
https://www.dropbox.com/s/019f4xqgu8r4i0e/DropDown.png
To do this, I ended up creating 3 different ComboBoxItem styles. The first puts together a CheckBox, a TextBlock with the ContentPresenter, and a Rectangle. The second just has a Separator, and the last just has the TextBlock with the ContentPresenter. Here is my XAML, which is declared in the UserControl.Resources section:
<Style x:Key="cbTestStyle" TargetType="{x:Type ComboBoxItem}">
<Setter Property="SnapsToDevicePixels" Value="True"/>
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="VerticalAlignment" Value="Stretch"/>
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBoxItem">
<Border Name="Border"
Padding="5"
Margin="2"
BorderThickness="2"
CornerRadius="0"
BorderBrush="Transparent">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="20"/>
<ColumnDefinition Width="75"/>
<ColumnDefinition Width="15"/>
</Grid.ColumnDefinitions>
<CheckBox Grid.Column="0"
IsChecked="{Binding Path=IsSelected, RelativeSource={RelativeSource TemplatedParent}}"/>
<TextBlock Grid.Column="1"
TextAlignment="Left"
Foreground="Black">
<ContentPresenter/>
</TextBlock>
<Rectangle Grid.Column="2"
Stroke="Black"
Width="15"
Height="15"
Fill="{TemplateBinding Foreground}"/>
</Grid>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsHighlighted" Value="True">
<Setter TargetName="Border" Property="BorderBrush" Value="Gray"/>
<Setter TargetName="Border" Property="Background" Value="LightGray"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="cbSeparatorStyle" TargetType="ComboBoxItem">
<Setter Property="SnapsToDevicePixels" Value="True"/>
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="VerticalAlignment" Value="Stretch"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<Separator/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="cbResetStyle" TargetType="{x:Type ComboBoxItem}">
<Setter Property="SnapsToDevicePixels" Value="True"/>
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="VerticalAlignment" Value="Stretch"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBoxItem">
<Border x:Name="Border"
Padding="5"
Margin="2"
BorderThickness="2"
CornerRadius="0"
BorderBrush="Transparent">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="20"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="1">
<ContentPresenter/>
</TextBlock>
</Grid>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsHighlighted" Value="True">
<Setter TargetName="Border" Property="BorderBrush" Value="Gray"/>
<Setter TargetName="Border" Property="Background" Value="LightGray"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
I guess my first question would be, is this the best way to make my ComboBox look like the screenshot I have presented?
Of course, there are deeper issues that I have yet to address. Firstly, the cbTestStyle of ComboBoxItem I want to be able to populate dynamically. Databinding would be my obvious go-to, but with the separator and "Reset" styles at the end, I'm not sure how to do this. I currently have the ComboBoxItems "hard-coded" in XAML:
<ComboBox x:Name="cbTestSelect"
Height="34"
Width="18"
IsEnabled="False">
<ComboBoxItem Style="{StaticResource cbTestStyle}" Content="Test 1" Foreground="#7FFF0000" Selected="ComboBoxItem_Selected"/>
<ComboBoxItem Style="{StaticResource cbTestStyle}" Content="Test 2" Foreground="#7F00FF00" Selected="ComboBoxItem_Selected"/>
<ComboBoxItem Style="{StaticResource cbTestStyle}" Content="Test 3" Foreground="#7F0000FF" Selected="ComboBoxItem_Selected"/>
<ComboBoxItem Style="{StaticResource cbSeparatorStyle}"/>
<ComboBoxItem Style="{StaticResource cbResetStyle}" Content="Reset all"/>
</ComboBox>
In this example, I would ideally like to dynamically create the first three items and have the separator and "reset" items remain static. I'm still relatively new to WPF. I felt like trying to create this control in WinForms (which the application this user control would be used in is) would be a lot more complicated. Plus I'm trying to steer us towards using WPF more anyway.
Any help or links to other questions or tutorials online would be greatly appreciated.
Solution 1:
Use a CompositeCollection so that you can bring up your data items with DataBinding, and use regular XAML to define the hard-coded items:
<Window x:Class="WpfApplication31.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication31"
Title="MainWindow" Height="350" Width="525"
x:Name="view">
<Window.Resources>
<DataTemplate DataType="{x:Type local:DataItem}">
<StackPanel Orientation="Horizontal">
<CheckBox IsChecked="{Binding IsChecked}"/>
<TextBlock Text="{Binding Text}"/>
<Rectangle Stroke="Black" StrokeThickness="1"
Fill="{Binding Color}" Width="20"/>
</StackPanel>
</DataTemplate>
</Window.Resources>
<Grid>
<ComboBox VerticalAlignment="Center"
HorizontalAlignment="Center"
Width="100" x:Name="Combo">
<ComboBox.Resources>
<CompositeCollection x:Key="ItemsSource">
<CollectionContainer Collection="{Binding DataContext,Source={x:Reference view}}"/>
<Separator Height="10"/>
<Button Content="Clear All"/>
</CompositeCollection>
</ComboBox.Resources>
<ComboBox.ItemsSource>
<StaticResource ResourceKey="ItemsSource"/>
</ComboBox.ItemsSource>
</ComboBox>
</Grid>
</Window>
Code Behind:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
var colors = new[] {"Red", "Green", "Blue", "Brown", "Cyan", "Magenta"};
this.DataContext =
Enumerable.Range(0, 5)
.Select(x => new DataItem
{
Text = "Test" + x.ToString(),
Color = colors[x],
IsChecked = x%2 == 0
});
}
}
Data Item:
public class DataItem
{
public bool IsChecked { get; set; }
public string Text { get; set; }
public string Color { get; set; }
}
Result:
Solution 2:
Using Expression Blend, you can get the XAML for the default Template for the ComboBox control, and modify this XAML to accomodate your extra visuals.
The XAML you get is rather long, and I'm not going to post it here. You will have to put that in a ResourceDictionary and reference that in the XAML where you define this ComboBox.
The relevant part you need to edit is the Popup:
<Popup x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
<Themes:SystemDropShadowChrome x:Name="shadow" Color="Transparent" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}">
<Border x:Name="dropDownBorder" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}">
<DockPanel>
<Button Content="Clear All" DockPanel.Dock="Bottom"/>
<Separator Height="2" DockPanel.Dock="Bottom"/>
<ScrollViewer x:Name="DropDownScrollViewer">
<Grid x:Name="grid" RenderOptions.ClearTypeHint="Enabled">
<Canvas x:Name="canvas" HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
</Canvas>
<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
</Grid>
</ScrollViewer>
</DockPanel>
</Border>
</Themes:SystemDropShadowChrome>
</Popup>
Notice that I added a DockPanel, the Button and a Separator.
Then you can bind your ItemsSource to the DataItem collection normally:
<ComboBox ItemsSource="{Binding}"
VerticalAlignment="Center"
HorizontalAlignment="Center"
Width="100"/>
Result:
Notice that this approach is a lot better than my previous solution, and other answers posted here, because it does not wrap the extra visuals in ComboBoxItems, and therefore you don't get the selection highlight for them, which is rather weird.
You could use a DataTemplateSelector with the DataTemplates defined in the XAML and some item type variable it the data you're binding to.
public class StyleSelector : DataTemplateSelector
{
public DataTemplate DefaultTemplate
{ get; set; }
public DataTemplate SeparatorTemplate
{ get; set; }
public DataTemplate ResetTemplate
{ get; set; }
public override DataTemplate SelectTemplate(object item, DependencyObject container)
{
var type = item as SomeType;
if (type != null)
{
switch (type.SomeItemTypeField)
{
case TypeENum.Separator: return SeparatorTemplate;
case TypeENum.Reset: return ResetTemplate;
default:
return DefaultTemplate;
}
}
return base.SelectTemplate(item, container);
}
}
Check out this more detailed example.
I think your best bet is to learn about DataTemplate and DataTemplateSelector.
Here is an blog post that will show you a simple example of using a DataTemplate.
The ComboBox Control
Essentially, you could bind your ComboBox to a collection of objects, and use a DataTemplateSelector to pick which template to use based on the type of object.

ItemContainerGenerator.ContainerFromItem() returns null while VirtualizingStackPanel.IsVirtualizing="False"

I'm facing a similar problem with this question however VirtualizingStackPanel.IsVirtualizing="False" didn't solve my problem. Is there anyone facing the same issue?
The thing is I have a custom combobox,
<Style TargetType="{x:Type MultiSelectionComboBox}" >
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<StackPanel Orientation="Vertical"
VerticalAlignment="Center"
HorizontalAlignment="Center"
VirtualizingStackPanel.IsVirtualizing="False"/>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate>
<StackPanel Orientation="Horizontal" x:Name="ItemStack" VirtualizingStackPanel.IsVirtualizing="False">
<CheckBox x:Name="CheckBoxItem"
Command="{Binding SelectItem, RelativeSource={RelativeSource AncestorType={x:Type MultiSelectionComboBox}}}"
CommandParameter="{Binding Key}"
>
</CheckBox>
<TextBlock Text="{Binding DisplayText}"></TextBlock>
</StackPanel>
</DataTemplate>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid x:Name="Placement" SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Border BorderThickness="1" BorderBrush="Black">
<TextBox IsReadOnly="True" Grid.Column="0"
Text="{Binding Text, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType={x:Type MultiSelectionComboBox}}}">
</TextBox>
</Border>
<Popup x:Name="PART_Popup"
Grid.Column="0"
Focusable="False"
Grid.ColumnSpan="2"
IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}, Mode=TwoWay}"
Placement="Bottom"
VerticalOffset="-1"
PlacementTarget="{Binding ElementName=LayoutRoot}">
<Popup.Resources>
<Style TargetType="{x:Type ScrollBar}" BasedOn="{StaticResource {x:Type ScrollBar}}">
<Style.Triggers>
<Trigger Property="Orientation" Value="Vertical">
<Setter Property="BorderThickness" Value="0"/>
</Trigger>
</Style.Triggers>
</Style>
</Popup.Resources>
<ScrollViewer x:Name="DropDownScrollViewer"
Background="{StaticResource Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
MinWidth="{Binding ActualWidth, ElementName=LayoutRoot}"
MaxHeight="{TemplateBinding MaxDropDownHeight}">
<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained"/>
</ScrollViewer>
</Popup>
<ToggleButton IsEnabled="{Binding IsEnabled, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType={x:Type MultiSelectionComboBox}}}" Grid.Column="1" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxToggleButton}"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>
and yet I can't get a reference to the checkbox inside via,
this.ItemContainerGenerator.ContainerFromItem(this.Items[0]) as ComboBoxItem;
Is there any suggestions?
What i actually want to achieve is,
i want to change checkboxes ischecked property which is depending on an other object which can change on runtime. I can't do it with using bindings due to the current state of the overall project which i can not change at this point. So basically once the new MultiSelectionComboBox is created i want to do something like this,
foreach (object item in this.Items)
{
ComboBoxItem comboBoxItem = this.ItemContainerGenerator.ContainerFromItem(item) as ComboBoxItem;
if (comboBoxItem == null)
continue;
FrameworkElement element = comboBoxItem.ContentTemplate.LoadContent() as FrameworkElement;
CheckBox checkBox = element.FindName("CheckBoxItem") as CheckBox;
checkBox.IsChecked = this.SelectedItem.Contains(item);
}
try execute UpdateLayout() before this.ItemContainerGenerator.ContainerFromItem(item)
Use ItemContainerGenerator.StatusChanged event from you ComboBox like this:
myComboBox.ItemContainerGenerator.StatusChanged += ItemContainerGenerator_StatusChanged;
void ItemContainerGenerator_StatusChanged(object sender, System.EventArgs e)
{
if (myComboBox.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated)
{
foreach (var item in myComboBox.Items)
{
var container = (ComboBoxItem)LanguageComboBox.ItemContainerGenerator.ContainerFromItem(item);
}
}
}
As my logic was in the SelectionChanged event, i wondered why the ItemContainerGenerator.ContainerFromItem method always returned null even if the Listbox.SelectedItem was not null and even more strange, Virtualisation was turned off! Looking at the ItemContainerGenerator.Status i saw that it was Primitives.GeneratorStatus.NotStarted then i added a simple test on ItemContainerGenerator.Status == Primitives.GeneratorStatus.ContainersGenerated and finally solved it that way and no need to subsribe to the Status_Changed event.

Click in TextBox Part of ComboBox

We have a Style for ComboBox like:
<Style x:Key="OurComboBox" TargetType="ComboBox">
<!-- omitted style Properties -->
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBox">
<Grid>
<ToggleButton Name="ToggleButton"
Grid.Column="2"
ClickMode="Press"
Focusable="false"
IsChecked="{Binding Path=IsDropDownOpen,
Mode=TwoWay,
RelativeSource={RelativeSource TemplatedParent}}"
Style="{StaticResource ComboBoxToggleButton}" />
<ContentPresenter Name="ContentSite"
Margin="3,3,23,3"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
IsHitTestVisible="False" />
<TextBox x:Name="PART_EditableTextBox"
Margin="5,3,23,1"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Background="Transparent"
Focusable="False"
FontFamily="Arial Narrow"
FontWeight="DemiBold"
Foreground="#FF404040"
IsReadOnly="True"
PreviewMouseDown=""
Style="{x:Null}"
Template="{StaticResource ComboBoxTextBox}"
Text="{TemplateBinding Text}"
Visibility="Hidden" />
<!-- omitted PopUp and ControlTemplate.Triggers -->
And based on that, we have another more specific style
<Style x:Key="comboBoxSpecialPage"
BasedOn="{StaticResource OurComboBox}"
TargetType="ComboBox">
<Style.Triggers>
<Trigger Property="SelectedIndex" Value="-1">
<Setter Property="Text" Value="Select value" />
</Trigger>
</Style.Triggers>
</Style>
Which leads to the text "Select value" if nothing is selected in the ComboBox, e.g. on start of the application.
But when I click directly on the TextBox text, nothing happens.
So the question is:
How to achieve that the PopUp is opened, as it does when the rest of the
ComboBox (the part without Text) is clicked?
-edit-
If I omited interesting parts, please let me know, I will add them then.
Perhaps IsHitTestVisible property is what you are looking for, more info here:
Textbox tag and IsHitTestVisible property
ComboBox has a property called DropDownStyle.
Set this to DropDownList and the text area is no longer editable, i.e you have to select from the list.

Styling individual cells in a listview

On the internet I found many examples of styling a complete column or complete row in a listview.
I need to be able to dynamically style individual cells in the listview. How can I access the properties of individual items in a row?
If you've got a finite number of properties in your data objects that you want to use to style your items, you can create data templates and styles, and use data triggers to switch between them. I've used something like this to alter the appearance of data objects in a list based on if they are "active/inactive" and to create a collapsed/expanded version of the object based on whether it's selected or not.
You can also use converters (built-in or custom) to get some effects easily. For example, I used a built-in boolean to visibility converter to hide/unhide the combobox/textblock in my TaskSelectedTemplate based on if the object's IsActive member.
<DataTemplate x:Key="TaskSelectedTemplate">
<Grid Margin="4">
...
<Border Grid.Row="0" Grid.Column="0" Grid.RowSpan="4" Margin="0 0 4 0"
BorderThickness="0"
CornerRadius="2">
<Border.Background>
<MultiBinding Converter="{StaticResource ActiveToColor}">
<Binding Path="."/>
<Binding Path="IsActive"/>
<Binding Path="IsPaused"/>
</MultiBinding>
</Border.Background>
</Border>
<StackPanel Grid.Row="0" Grid.Column="1"
Orientation="Horizontal"
Margin="0 2">
<ComboBox ItemsSource="{Binding Source={StaticResource TaskTypes}}"
SelectedItem="{Binding Type}"
Text="{Binding Type}"
Visibility="{Binding IsActive, Converter={StaticResource BoolToVis}}"/>
<TextBlock Text="{Binding Type}"
FontWeight="Bold"
Visibility="{Binding IsActive, Converter={StaticResource InvBoolToVis}}"/>
<TextBlock Text=" task"/>
</StackPanel>
...
</Grid>
</DataTemplate>
<DataTemplate x:Key="TaskNotSelectedTemplate">
<Grid Margin="4">
...
<Border Grid.Row="0" Grid.Column="0" Grid.RowSpan="4" Margin="0 0 4 0"
BorderThickness="0"
CornerRadius="2">
<Border.Background>
<MultiBinding Converter="{StaticResource ActiveToColor}">
<Binding Path="."/>
<Binding Path="IsActive"/>
<Binding Path="IsPaused"/>
</MultiBinding>
</Border.Background>
</Border>
<TextBlock Grid.Row="0" Grid.Column="1"
Text="{Binding Type}"/>
<TextBlock Grid.Row="0" Grid.Column="2"
TextAlignment="Right">
<Run Text="{Binding Length.TotalMinutes, StringFormat='0', Mode=OneWay}"/>
<Run Text=" min"/>
</TextBlock>
<TextBlock Grid.Row="0" Grid.Column="3"
TextAlignment="Right">
<Run Text="{Binding TimesPerformed, Mode=OneWay}"/>
<Run Text=" tasks"/>
</TextBlock>
</Grid>
</DataTemplate>
<Style x:Key="ContainerStyle" TargetType="{x:Type ListBoxItem}">
<!--this part changes the selected item highlight color-->
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListBoxItem}">
<Border Name="Border">
<ContentPresenter />
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSelected" Value="true">
<Setter TargetName="Border"
Property="Background" Value="#2000BFFF">
</Setter>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<!--this part causes selected task to expand-->
<Setter Property="ContentTemplate" Value="{StaticResource TaskNotSelectedTemplate}"/>
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="ContentTemplate" Value="{StaticResource TaskSelectedTemplate}"/>
</Trigger>
</Style.Triggers>
</Style>
For more complex scenarios, you might want to look at DataTemplateSelector. I've never used it, but it seems like it might be ideal if you've got a lot of data templates to juggle.
Generally speaking, you shouldn't need this. Assuming you are using GridView, you should be able to use CellTemplate or CellTemplateSelector of your GridViewColumns.
If you really want to access specific cells, I think there is no clean way, you'd be better using DataGrid (from .Net 4 or WPF toolkit for .Net 3.5). With that, you can do something like this:
((TextBlock)datagrid.Columns[1].GetCellContent(m_specificItem)).Background = Brushes.Red

WPF - Change a style in code behind

I have a list box that displays the results of a TFS Query. I want to change the style of the ListBoxItem in the code behind to have the columns that are included in the query results.
The style for the ListBoxItem is defined in my Windows.Resoruces Section. I have tried this:
public T GetQueryResultsElement<T>(string name) where T : DependencyObject
{
ListBoxItem myListBoxItem =
(ListBoxItem)(lstQueryResults.ItemContainerGenerator.ContainerFromIndex(0));
// Getting the ContentPresenter of myListBoxItem
ContentPresenter myContentPresenter =
myListBoxItem.Template.LoadContent().FindVisualChild<ContentPresenter>();
// Finding textBlock from the DataTemplate that is set on that ContentPresenter
DataTemplate myDataTemplate = myContentPresenter.ContentTemplate; <------+
T myControl = (T)myDataTemplate.FindName(name, myContentPresenter); |
|
return (T)myControl; |
} |
|
ContentTemplate is null ----------------------------------------------+
But the ContentTemplate is null. I got that code from here, then modified it with the LoadContent call (the orginal code gave null for the ContentPresenter).
Anyway. If you know a way to change an existing style in the code behind I would love to see it.
Specifics if you want them:
I am going for WrapPanel in my ListBoxItem Style. This is what I want to add the extra TextBlock items to.
Here is part of my style:
<!--Checkbox ListBox-->
<Style x:Key="CheckBoxListStyle" TargetType="ListBox">
<Style.Resources>
<Style x:Key="ListBoxItemStyle" TargetType="ListBoxItem">
<Setter Property="Tag" Value="{Binding Id}"/>
<Setter Property="Background">
<Setter.Value>
<Binding Path="Type" Converter="{StaticResource WorkItemTypeToColorConverter}" />
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<Border BorderThickness="1" BorderBrush="#D4D4FF">
<Grid Width="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type WrapPanel}}, Path=ActualWidth}" ScrollViewer.CanContentScroll="True" Margin="2">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="20" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="30" />
</Grid.ColumnDefinitions>
<Grid.Background>
<Binding Path="Type" Converter="{StaticResource WorkItemTypeToColorConverter}" />
</Grid.Background>
<CheckBox VerticalAlignment="Center" Grid.Column="0" IsChecked="{Binding IsSelected,
RelativeSource={RelativeSource TemplatedParent},
Mode=TwoWay}" Name="chkIsSelected" />
<WrapPanel Grid.Column="1" Margin="5,0,5,0" Name="QueryColumns">
<TextBlock VerticalAlignment="Center" Text="{Binding Id}" Name="txtID" />
<TextBlock VerticalAlignment="Center" Margin="5,0,5,0" Text="{Binding Title}" Name="txtTitle" />
</WrapPanel>
You're going against the grain here, trying to manipulate visual elements directly in code-behind. There's a much simple solution involving data binding.
I'll provide the general solution because I don't know the specifics of your solution.
Once you get your query results, create an enumeration that returns a column name, and a field value for each iteration.
Example:
class NameValuePair
{
public string Name { get; set; }
public object Value { get; set; }
}
public IEnumerable<IEnumerable<NameValuePair>> EnumerateResultSet(DataTable resultSet)
{
foreach (DataRow row in resultSet.Rows)
yield return EnumerateColumns(resultSet, row);
}
public IEnumerable<NameValuePair> EnumerateColumns(DataTable resultSet, DataRow row)
{
foreach (DataColumn column in resultSet.Columns)
yield return new NameValuePair
{ Name = column.ColumnName, Value = row[column] };
}
And in your code-behind, once you get your DataTable result set, do this:
myResultsList.ItemsSource = EnumerateResultSet(myDataTable);
The XAML might look like this:
<Window.Resources>
<DataTemplate x:Key="ColumnTemplate">
<Border BorderBrush="Black" BorderThickness="1" CornerRadius="2" Padding="2">
<WrapPanel>
<TextBlock Text="{Binding Name}" Margin="0,0,5,0"/>
<TextBlock Text="{Binding Value}" Margin="0,0,10,0"/>
</WrapPanel>
</Border>
</DataTemplate>
<DataTemplate x:Key="RowTemplate">
<Grid>
<ItemsControl
ItemsSource="{Binding}"
ItemTemplate="{StaticResource ColumnTemplate}"
Margin="0,5,0,5"/>
</Grid>
</DataTemplate>
</Window.Resources>
<Grid>
<ListBox Name="myResultsList" ItemTemplate="{StaticResource RowTemplate}"/>
</Grid>
Sample output:

Categories

Resources