WPF Animation dependency issue

Question

I just started to learn WPF and XAML and I tried to gete an animation sample to work on my machine. Basically, a label background should change when a specific value is set in the corresponding textbox. Issue is I get the following error: Background' property does not point to a DependencyObject in path '(0).(1)

This is the XAML:

<Window x:Class="WpfDataBinding.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:loc="clr-namespace:WpfDataBinding"
    Title="MainWindow" Height="350" Width="264.828">
<Window.Resources>
    <DataTemplate DataType="{x:Type loc:Person}">
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="210"/>
            </Grid.ColumnDefinitions>
            <TextBlock Name="nameLabel" Grid.Row="0" Grid.Column="0" Text="Name:" FontSize="14" Margin="3,3,0,0"/>
            <TextBox Name="nameTextBox" Grid.Row="0" Grid.Column="1" Width="200" Text="{Binding Name}" FontSize="14" Margin="3" />
            <TextBlock Name="ageLabel" Grid.Row="1" Grid.Column="0" Text="Age:" FontSize="14" Margin="3,3,0,0"/>
            <TextBox Name="ageTextBox" Grid.Row="1" Grid.Column="1" Width="200" Text="{Binding Age}" FontSize="14" Margin="3"/>
        </Grid>
        <DataTemplate.Triggers>
            <DataTrigger Binding="{Binding Age}" Value="21">
                <DataTrigger.EnterActions>
                    <BeginStoryboard>
                        <Storyboard>
                            <ColorAnimation Storyboard.TargetName="ageLabel"
                                            Storyboard.TargetProperty="(Label.Background).(SolidColorBrush.Color)"
                                            To="Red" Duration="0:0:1"/>
                        </Storyboard>
                    </BeginStoryboard>
                </DataTrigger.EnterActions>
            </DataTrigger>
        </DataTemplate.Triggers>
    </DataTemplate>
</Window.Resources>
<Grid Margin="0,0,0,-0.2" HorizontalAlignment="Left" Width="248">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <ListBox ItemsSource="{Binding}" />
    <StackPanel Grid.Row="2" Grid.ColumnSpan="2">
        <Button Content="_Show.." Click="Button_Click"/>
        <Button Content="_Age" Click="Button_Click_1"/>
    </StackPanel>
</Grid>

Thank you

Clemens · Answer 1 · 2016-01-15T14:55:06.130

In order to animate the Color property of a SolidColorBrush in the Background property of a UI Element, you need to first set the Background. The default value of the Background property of a TextBlock is null, so there is nothing to animate.

So, first set a Background before animating it:

<TextBlock ...>
    <TextBlock.Background>
        </SolidColorBrush Color="Transparent"/>
    </TextBlock.Background>
</TextBlock>

Now your could write the TargetProperty path like

Storyboard.TargetProperty="Background.Color"

or

Storyboard.TargetProperty="(TextBlock.Background).Color"

or

Storyboard.TargetProperty="(TextBlock.Background).(SolidColorBrush.Color)"

or even

Storyboard.TargetProperty="Background.(SolidColorBrush.Color)"

All expressions are equivalent. The details are explained in the PropertyPath XAML Syntax article on MSDN.

score 1 · Answer 2 · edited May 23 '17 at 12:23

1

As per this question you need to use:

ColorAnimation Storyboard.TargetName="ageLabel"
Storyboard.TargetProperty="(TextBlock.Background).Color"
To="Red" Duration="0:0:1"/>

rather than (TextBlock.Background).(SolidColorBrush.Color) as apparently Background and SolidColorBrush are the same object.

edited May 23 '17 at 12:23

Community

1
1

answered Jan 15 '16 at 12:52

spaceplane

607
1
12
27

I used it and now I get this error: Cannot resolve all property references in the property path '(0).Color'. Verify that applicable objects support the properties. – Octavian Epure Jan 15 '16 at 13:12
This is not true. Both expressions `(TextBlock.Background).Color` and `(TextBlock.Background).(SolidColorBrush.Color)` are equivalent. – Clemens Jan 15 '16 at 14:39
@Clement - Well, how do you explain the error, then ? – Octavian Epure Jan 15 '16 at 14:47
@OctavianEpure See my answer. – Clemens Jan 15 '16 at 14:47
@spaceplane. It's always a good idea to validate solutions before copying and pasting from other answers. – Clemens Jan 15 '16 at 14:57
Thanks for the advice. Ill remove my answer. – spaceplane Jan 15 '16 at 16:27

Radin Gospodinov · Answer 3 · 2016-01-15T12:42:10.493

0

(Label.Background).(SolidColorBrush.Color) line is the problem. It needs to be <ColorAnimation Duration="0" To="Red" Storyboard.TargetProperty="(TextBlock.Background).(SolidColorBrush.Color)" Storyboard.TargetName="ageLabel" />

edited Jan 15 '16 at 12:42

answered Jan 15 '16 at 12:27

Radin Gospodinov

2,313
13
14

I did this and I got a different error: 'System.Windows.Media.Animation.ColorAnimation' animation object cannot be used to animate property 'Background' because it is of incompatible type 'System.Windows.Media.Brush'. – Octavian Epure Jan 15 '16 at 12:36
I edited my answer ageLabel is of type TextBlock so you should use (TextBlock.Background).(SolidColorBrush.Color) – Radin Gospodinov Jan 15 '16 at 12:43
I used TextBlock.Background, and I get the first error showing up again. Strange thing is, I get this error when I raise an notification event for the textbox value change. If I comment the event raise, just to test, I no longer get the error but the animation does'nt work anyway. – Octavian Epure Jan 15 '16 at 12:51

WPF Animation dependency issue

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