I have defined the names and color in the backend using C# so I want to select the item cat and change it's other elements.
You don't show the XAML you are using to set up the ComboBox but best approach is to use a data template to set up the ComboBox items however you wish them to look. If you want the color box to not be shown if the Color brush is null, you could then add a trigger to the template to make it Hidden. Note that if you make it collapsed it will realign the layout of the other controls.
<DataTemplate x:Key="cbDataTemplate">
<StackPanel Orientation="Horizontal">
<Rectangle x:Name="clrBox" Fill="{Binding Color, TargetNullValue=Transparent}"
Stroke="Black" StrokeThickness="2" Width="16"/>
<TextBlock Text="{Binding Name}" Margin="10,0,0,0"/>
</StackPanel>
<DataTemplate.Triggers>
<DataTrigger Binding="{Binding Color}" Value="{x:Null}">
<Setter TargetName="clrBox" Property="Visibility" Value="Hidden"/>
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
then to use this DataTemplate simply add it to the ComboBox like this:
<ComboBox ItemTemplate="{StaticResource cbDataTemplate}" Width="150"/>
hope that's helpful...
Related
Is there a quick and easy way to implement a color picker button like the one in MS Word?
I want the user to choose from a number of predefined colors in a dropdown. The selected color should be displayed when the button is closed. When the user clicks the button, an event or command should be triggered. I want to use one button instance to set the text color in a RichTextBox, and another one to set the background color (similar to MS Word).
My first approach was to use a ComboBox with a DataTemplate which contains a button.
This does not work: The button's command is not triggered when the user clicks it. Instead, the dropdown of the ComboBox opens. I don't know the exact reason, but maybe the IsHitTestVisible=false attributes in the ComboBox default template? See: http://msdn.microsoft.com/en-us/library/dd334408%28v=vs.95%29.aspx
<UserControl x:Class="MyBrushPicker"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
Height="Auto" Width="Auto" MinWidth="50">
<UserControl.Resources>
<!--
Provide two different DataTemplates:
- SelectionBoxTemplate is used to display the selected color when the ComboBox is closed.
It contains a button which should be clickable (does not work).
- NormalItemTemplate is used to display a color in the opened ComboBox popup.
See:
http://stackoverflow.com/questions/2214696/wpf-how-to-customize-selectionboxitem-in-combobox
-->
<DataTemplate x:Key="NormalItemTemplate">
<Border Height="44" Width="44" Margin="3,3,3,3" BorderThickness="1" BorderBrush="Black" Background="{Binding Mode=OneWay}"/>
</DataTemplate>
<DataTemplate x:Key="SelectionBoxTemplate">
<!-- This button cannot be clicked: PreviewMouseDown and Button_Click events are never triggered. -->
<Button Click="Button_Click" PreviewMouseDown="Button_PreviewMouseDown">
<Border Height="44" Width="44" Margin="3,3,3,3" BorderThickness="1" BorderBrush="Black" Background="{Binding Mode=OneWay}"/>
</Button>
</DataTemplate>
<DataTemplate x:Key="CombinedTemplate">
<ContentPresenter x:Name="Presenter"
Content="{Binding}"
ContentTemplate="{StaticResource NormalItemTemplate}" />
<DataTemplate.Triggers>
<DataTrigger
Binding="{Binding RelativeSource={RelativeSource FindAncestor,ComboBoxItem,1}}"
Value="{x:Null}">
<Setter TargetName="Presenter" Property="ContentTemplate"
Value="{StaticResource SelectionBoxTemplate}" />
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
</UserControl.Resources>
<ComboBox IsReadOnly="True" IsEditable="False"
ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=SelectableBrushes, Mode=OneWay}"
SelectedItem="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=SelectedBrush, Mode=TwoWay}"
ScrollViewer.VerticalScrollBarVisibility="Auto"
MinHeight="50"
MaxDropDownHeight="200"
ItemTemplate="{StaticResource CombinedTemplate}"
>
<ComboBox.Resources>
<Style TargetType="ComboBox">
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<WrapPanel IsItemsHost="True" Orientation="Horizontal" Width="200" />
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="ComboBoxItem">
<Setter Property="Width" Value="50" />
<Setter Property="Height" Value="50" />
</Style>
</ComboBox.Resources>
</ComboBox>
</UserControl>
Is there a way to make the button work correctly?
Are there any better approaches?
EDIT: Using the Snoop tool revealed that the IsHitTestVisible attribute of the unnamed ContentPresenter inside the ComboBox is actually set to false (ValueSource: ParentTemplate). If I set this property to true using Snoop, the button becomes clickable.
Can I change this property from a style?
At least, the following doesn't work:
<ComboBox.Resources>
<Style TargetType="ContentPresenter">
<Setter Property="IsHitTestVisible" Value="True" />
</Style>
</ComboBox.Resources>
Assuming you are not just doing this as a learning exercise (which make using a library pointless)...
Take a look at: Extended WPF Toolkit - Color Picker
I've used it before for simple a plug-and-play WPF color-picker and it should solve your problem nicely.
I have an image control on which the user can drag and drop pictures. When no image has been dropped in there and the control is empty, I'd like to show an alternative text such as "Drop a picture here" to better indicate what is expected from him/her.
I can't figure out how to use triggers with this, this shows nothing at all and I can no longer drop pictures on my image control:
<StackPanel Grid.Column="1" Grid.Row="2" FlowDirection="LeftToRight" Orientation="Horizontal" Margin="0px 4px">
<StackPanel.Resources>
<DataTemplate x:Key="tmpTemplate">
<Border BorderThickness="2" BorderBrush="#FF969DFF" CornerRadius="2" VerticalAlignment="Top">
<DockPanel>
<Image Name="imgSelectedViewImage" Source="{Binding Image}" MinWidth="32" MinHeight="32" MaxWidth="48" MaxHeight="48"
HorizontalAlignment="Left" Stretch="None"
IsEnabled="{Binding EditMode}" Margin="2px"/>
<Label Content="Drag here" Name="AltText" Visibility="Collapsed"></Label>
</DockPanel>
</Border>
<DataTemplate.Triggers>
<DataTrigger Binding="{Binding Path=Image}" Value="{x:Null}">
<Setter TargetName="AltText" Property="Visibility" Value="Visible" />
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
</StackPanel.Resources>
I can't tell you what you've done to break your previously working drag and drop functionality and all I can do is to suggest you undo your changes to remedy that. However, if you want to display something when a collection is empty, then there's an easy way to do that. Using the collection's Count property is no good because it won't update when items are added or removed.
You can simply add an int property next to your item collection for this, but you have to make sure that you notify the INotifyPropertyChanged interface for it also when the collection property changes:
public ObservableCollection<YourItem> YourItems
{
get { return yourItems; }
set
{
yourItems = value;
NotifyPropertyChanged("YourItems");
NotifyPropertyChanged("YourItemsCount");
}
}
public int YourItemsCount
{
get { return YourItems.Count; }
}
Then you can use it in a simple DataTrigger like this:
<Grid>
<!-- Put your normal content here -->
<TextBlock FontSize="16" HorizontalAlignment="Center" VerticalAlignment="Center"
Text="Drop images here">
<TextBlock.Style>
<Style>
<Setter Property="TextBlock.Visibility" Value="Collapsed" />
<Style.Triggers>
<DataTrigger Binding="{Binding YourItemsCount}" Value="0">
<Setter Property="TextBlock.Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
</Grid>
I did it by setting the TargetNullValue and the FallbackValue to a static resource. See the code snippet below. You can of course set it to everything else you want.
<Image Stretch="Uniform"
Grid.Row="0"
Grid.Column="1"
MaxHeight="250"
MaxWidth="250"
Margin="10"
Source="{Binding Path=Character.Portrait, TargetNullValue={StaticResource FallbackImage}, FallbackValue={StaticResource FallbackImage}}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="MouseDoubleClick">
<cal:ActionMessage MethodName="ChangePicture">
</cal:ActionMessage>
</i:EventTrigger>
</i:Interaction.Triggers>
</image>
Another approach, which could be more to your liking, as it uses triggers could be this solution: Handling null when binding to an Image in XAML (look at the accepted answer). However in my opinion setting TargetNullValue and the FallbackValue is the best way to go.
I am using a Combobox whose ItemSource is ObservableCollection(i.e. ConversationList) of type .
<ComboBox x:Name="ConvId"
Grid.Row="2"
Width="75"
Height="23"
Margin="6,94,0,0"
HorizontalAlignment="Left"
VerticalAlignment="Top"
ItemsSource="{Binding ConversationList,
UpdateSourceTrigger=PropertyChanged}"
SelectedItem="{Binding SelectedId,
Mode=TwoWay}">
My requirement is : when there is no int value in Collection then Combobox Left side should display 'ConvId' which is a string. Fig. is shown below
I have workaround i.e to Convert collection from int to string and put 'ConvId' on 0th location and mark SelectedIndex= 0. but its not we want.
Do I have to use some Custom control for this. Is there any to acheive this in XAML.
This Stack thread seems to do what you want cleanly with a Converter.
How to display default text "--Select Team --" in combo box on pageload in WPF?
The answer I am referring to starts with this:
<Grid>
<ComboBox
x:Name="comboBox1"
ItemsSource="{Binding MyItemSource}" />
<TextBlock
Visibility="{Binding SelectedItem, ElementName=comboBox1, Converter={StaticResource NullToVisibilityConverter}}"
IsHitTestVisible="False"
Text="... Select Team ..." />
</Grid>
Have below textblock below your combobox and make sure that both combobox and textblock are overlapping each other(i.e. they should be in same grid row)
<TextBlock Text="ConvID"
IsHitTestVisible="False">
<TextBlock.Style>
<Style
TargetType="TextBlock">
<Setter
Property="Visibility"
Value="Collapsed" />
<Style.Triggers>
<DataTrigger
Binding="{Binding ConversationList.Count}"
Value="0">
<Setter
Property="Visibility"
Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
Hope this helps.
Have a look at the WatermarkService by John Myczek. You can have it display a default string if no item is selected in the ComboBox. There's some issues with ComboBox in the answer I linked to, but if you look further down there's a fix for that.
In WPF, MVVC applicaiton I have quite normal listbox:
<ListBox ItemsSource="{Binding Friends}">
</ListBox>
Then each item of list uses following datatemplate:
<DataTemplate DataType="{x:Type model:Friend}">
<Border BorderThickness="1" BorderBrush="Gray" Padding="3" Name="border" Margin="3">
<StackPanel Grid.Row="1" Grid.Column="2" Orientation="Horizontal">
<TextBlock Name="DescriptionDTDataType" Text="{Binding Path=ConnectedUserID}" />
<TextBlock Name="StatusTitle" Margin="8,0,4,0">Status:</TextBlock>
<TextBlock Name="Status" Text="{Binding Path=Approved}" />
<Button Content="Approve" Command="{x:Static inf:Commands.ApproveUserConnection}" CommandParameter="{Binding}"></Button>
<Button Content="Disapprove" Command="{x:Static inf:Commands.DisapproveUserConnection}" CommandParameter="{Binding}"></Button>
</StackPanel>
</Border>
</DataTemplate>
The question is... I want to hide one of the buttons on the basic of Friend.Approved property. For example if Friend.Approved has value "approved" I want to hide button Approved and show only button Dissaprove. On the other hand if Friend.Approved has value "disapproved" then I want opposite. How to achieve this?
Thank you.
Beside creating a IValueConverter there is a pure XAML solution using DataTriggers
Just add this to your DataTemplate:
<DataTemplate.Triggers>
<DataTrigger Binding="{Binding Approved}" Value="approved" >
<Setter TargetName="Approve" Property="Visibility" Value="Collapsed"/>
</DataTrigger>
<DataTrigger Binding="{Binding Approved}" Value="disapproved" >
<Setter TargetName="Disapprove" Property="Visibility" Value="Collapsed"/>
</DataTrigger>
</DataTemplate.Triggers>
And name your buttons:
<Button Name="Approve" Content="Approve" ...></Button>
<Button Name="Disapprove" Content="Disapprove" ...></Button>
However if you want to reuse this hiding logic in multiple places in multiple DataTemplates its better to write the Approved text to Visibility converter.
Bind the Buttons Visibility property to Approved and use a value converter to convert Approved to a Visibility value.
i need to remove red rectangle around combobox. I have setup combobox in xaml like (below) this and i`m trying to override of the Validation.ErrorTemplate.
<ComboBox x:Name="comboPodkategoria"
Margin="0,3,0,0"
IsSynchronizedWithCurrentItem="False"
IsEditable="False"
ItemsSource="{Binding Source={StaticResource PodKategoriaLookup}, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}"
SelectedValue="{Binding IDPodKategoria}"
DisplayMemberPath="kat_popis" SelectedValuePath="IDPodkat" TabIndex="5" Style="{StaticResource combostyle}">
<Validation.ErrorTemplate>
<ControlTemplate>
</ControlTemplate>
</Validation.ErrorTemplate>
</ComboBox>
And style for removing red rectangle, but a have some error in xaml saying that Visibility property is not recognized or is not accessible. Style definition is below.
<Style x:Key="combostyle">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="True">
<Setter Property="Visibility" TargetName="NotValid" Value="Visible"/>
</Trigger>
</Style.Triggers>
Any idea? :(
Use this to modify the Validation.ErrorTemplate
<ControlTemplate x:Key="ComboBoxValidationErrorTemplate">
<DockPanel>
<Border BorderBrush="Blue" BorderThickness="4">
<AdornedElementPlaceholder />
</Border>
</DockPanel>
</ControlTemplate>
And then use it in your ComboBox like
<ComboBox Validation.ErrorTemplate="{StaticResource ComboBoxValidationErrorTemplate}"
...>
To have no indication of a Validation Error, remove the DockPanel, set Visibility to Collapsed or any other way you like.
Almost forgot, probably the easiest way to remove the "Red Border"
<ComboBox Validation.ErrorTemplate="{x:Null}"
...>
Add your Combobox, Validation.ErrorTemplate="{x:Null}" ; this code is ignore errors.
The setter in your trigger is setting the Visibility property of an element named "NotValid". That is not defined in the XAML you posted. If there is no element named "NotValid", that is your problem.