How to change WPF Rectangle Style Programatically

c#, datatrigger, mvvm, wpf, xaml

Solution

define two visual brushes in your resource and create a style of rectangle with data trigger like

  <VisualBrush x:Key="FailBrush">Black</VisualBrush>
    <VisualBrush x:Key="PassBrush">Red</VisualBrush>

    <Style x:Key="ColorRectangleStyle" TargetType="Rectangle">
        <Setter Property="Fill" Value="{StaticResource FailBrush}"/>
        <Style.Triggers>
            <DataTrigger Binding="{Binding Passed}" Value="False">
                <Setter Property="Fill" Value="{StaticResource PassBrush}"/>
            </DataTrigger>
        </Style.Triggers>
    </Style>

and use it in rectangle like

<Rectangle Name="rectStatusImg" Width="120" Height="120" Grid.Row="2" Style="{StaticResource ColorRectangleStyle}" />

Hope it helps.

Problem

[EDIT] *I had forgotten to include the Exception returned `'System.Windows.Style' is not a valid value for property 'Fill'`* This is my first post, I've already done lots of searching for questions where this might have already been answered to no success. I'm a complete noob when it comes to MVVM, Prism, and WPF and I have been thrown in the deep end on this one. I wish to change the contents of 2 rectangles depending on a boolean in the Model (Binding Passed). if a test returns Pass (bool True) then we display colour Green for first rectangle, and the second rectangle will display the UserControl.Resource Style x:Key="RectanglePass". If test fails, then first rectangle is red, and second displays UserControl.Resource Style x:Key="RectangleFail" I have the following xaml code: ``` <UserControl x:Class="Integration.Memjet.Aoqc.Views.ProcessResultView" 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" d:DesignHeight="300" d:DesignWidth="300"> <UserControl.Resources> <Style x:Key="RectangleFail" TargetType="Rectangle"> <Setter Property="Fill"> <Setter.Value> <VisualBrush> .... </VisualBrush> </Setter.Value> </Setter> </Style> <Style x:Key="RectanglePass" TargetType="Rectangle"> <Setter Property="Fill"> <Setter.Value> <VisualBrush> .... </VisualBrush> </Setter.Value> </Setter> </Style> </UserControl.Resources> <Grid> <Grid.RowDefinitions> <RowDefinition Height="60"></RowDefinition> <RowDefinition Height="60"></RowDefinition> <RowDefinition></RowDefinition> </Grid.RowDefinitions> <Label VerticalAlignment="Center" HorizontalAlignment="Center" FontSize="20">PASS</Label> <Rectangle Name="rectStatus" Grid.Row="1"> <Rectangle.Style> <Style TargetType="{x:Type Rectangle}"> <Style.Triggers> <DataTrigger Binding="{Binding Passed}" Value="True"> <Setter Property="Fill" Value="Green" /> </DataTrigger> <DataTrigger Binding="{Binding Passed}" Value="False"> <Setter Property="Fill" Value="Red" /> </DataTrigger> </Style.Triggers> </Style> </Rectangle.Style> </Rectangle> <Rectangle Name="rectStatusImg" Width="120" Height="120" Grid.Row="2" > <Rectangle.Style> <Style TargetType="{x:Type Rectangle}"> <Style.Triggers> <DataTrigger Binding="{Binding Passed}" Value="True"> <Setter Property="Fill" Value="{StaticResource RectanglePass}" /> </DataTrigger> <DataTrigger Binding="{Binding Passed}" Value="False"> <Setter Property="Fill" Value="{StaticResource RectangleFail}" /> </DataTrigger> </Style.Triggers> </Style> </Rectangle.Style> </Rectangle> </Grid> </UserControl> ``` The above doesn't work and returns an exception. If I was to replace the second Rectangle tag (rectStatusImg) with this line; ``` <Rectangle Name="rectStatusImg" Style="{StaticResource RectanglePass}" Width="120" Height="120" Grid.Row="2" ></Rectangle> ``` the xaml works and produces the expected result! But I wish to bind it to the Boolean Passed so I can change it programmatically. I really hope I was able to explain my problem here. Thank you for your help in advance, this site has always been a treasure and a great help. Cheers, Simon

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