fix CheckBox animation throwing NullReferenceException on ObservableCollection changes

[Muniwedesu]

Use DependencyProperty for getting/setting the Tag property value to avoid it having the default value of 'null'

Pull request type

Please check the type of change your PR introduces:

• Update
• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes

What is the current behavior?

Issue Number: #1140

What is the new behavior?

• I didn't try to think about a proper solution/what's causing that issue and just used the code added in fix #1140 "System.ArgumentNullException: 'Value cannot be null. Parameter name: defaultDestinationValue'" #1398, it stopped throwing this exception in my use cases and animations seem to work properly.

Other information

[chucker]

Can you expand on what this fixes? You say #1140, but that one was closed (and thus presumably fixed) last year? Do you have a repro?

[Muniwedesu]

Can you expand on what this fixes? You say #1140, but that one was closed (and thus presumably fixed) last year? Do you have a repro?

That particular issue was with CardExpander and it was fixed, yes, this one does the same thing with CheckBox, maybe there are other controls like that.
And I should add that this only happens when resources are defined in the Window class (or anywhere else besides Application), I didn't notice that initially, sorry.

To reproduce just click on Remove/Clear button when checkbox is checked or was interacted with
wpfui-checkbox.zip

[Nuklon]

This is not complete, I don't have write access to the PR, but the Tag needs to be replaced as well:

                                        <controls:SymbolIcon.Clip>
                                            <MultiBinding Converter="{StaticResource ClipConverter}">
                                                <MultiBinding.Bindings>
                                                    <Binding Path="ActualWidth" RelativeSource="{RelativeSource Self}" />
                                                    <Binding Path="ActualHeight" RelativeSource="{RelativeSource Self}" />
                                                    <Binding Path="(animations:AnimationProperties.AnimationTagValue)" RelativeSource="{RelativeSource Self}" />
                                                </MultiBinding.Bindings>
                                            </MultiBinding>
                                        </controls:SymbolIcon.Clip>
                                        <animations:AnimationProperties.AnimationTagValue>
                                            <system:Double>1</system:Double>
                                        </animations:AnimationProperties.AnimationTagValue>

[Muniwedesu]

@Nuklon would you like to make a proper PR and I'll just close/delete mine then? (don't know how this works on github)

[Nuklon]

You should be able to fix the issue yourself with another commit on this branch :)

[chucker]

Somewhat minimal repro:

App.xaml:

<Application
    x:Class="wpfui1512bug.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    StartupUri="MainWindow.xaml"/>

MainWindow.xaml:

<Window
    x:Class="wpfui1512bug.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
    Title="MainWindow"
    Width="800"
    Height="450"
    AllowsTransparency="True"
    Loaded="MainWindow_OnLoaded"
    WindowStyle="None"
    mc:Ignorable="d">

    <Window.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ui:ThemesDictionary Theme="Light"/>
                <ui:ControlsDictionary/>
                <!-- <ResourceDictionary Source="FixedCheckBox.xaml"/> -->
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Window.Resources>

    <Grid x:Name="Root">
        <Grid x:Name="OuterContainer">
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="*"/>
            </Grid.RowDefinitions>

            <ui:TitleBar Title="Hello"/>

            <ContentControl x:Name="Host" Grid.Row="1">
                <CheckBox x:Name="OldCheckBox" Width="100">Is fancy</CheckBox>
            </ContentControl>
        </Grid>
    </Grid>
</Window>

MainWindow.xaml.cs:

using System.Windows;
using System.Windows.Controls;

namespace wpfui1512bug;

public partial class MainWindow 
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private async void MainWindow_OnLoaded(object sender, RoutedEventArgs e)
    {
        OldCheckBox.IsChecked = true;

        // force some of the checkbox animation to play
        await Task.Delay(500);

        Host.Content = new CheckBox
        {
            Content = "got here"
        };
    }
}

Merely launching that will crash:

Unhandled Exception: System.ArgumentNullException: Value cannot be null.
Parameter name: defaultDestinationValue
   at System.Windows.Media.Animation.DoubleAnimationBase.GetCurrentValue(Object defaultOriginValue, Object defaultDestinationValue, AnimationClock animationClock)
   at System.Windows.Media.Animation.AnimationLayer.GetCurrentValue(Object defaultDestinationValue)
…

Uncomment <!-- <ResourceDictionary Source="FixedCheckBox.xaml"/> --> with the implementation from this PR, and that crash is resolved.

I can't get it to reproduce when WPF UI is part of the application style, but regardless, there's a bug in the animation here, introduced between 4.0.3 and 4.1, so #1512 would be my guess.