Develop Reference

How to control a storyboard animation from C# and XAML

There's a lot of questions around this on the net, but after reading them, and the MS docs on animation control, I'm unable to mimic storyboard control from XAML event triggers in C# code.
In this XAML file, I have a canvas that I am rotating. I'd like to add interactivity to the rotation,
<Window x:Class="GraphicsBook.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:k="clr-namespace:GraphicsBook;assembly=Testbed2D"
Title="2D Testbed"
KeyDown="KeyDownHandler"
Height="600"
Width="600" >
<DockPanel LastChildFill="True">
<StackPanel x:Name="stack" DockPanel.Dock ="Top" Orientation="Vertical" Background="#ECE9D8">
<Button Name="StartAnimationClick">Start animation</Button>
<Button Name="StopAnimationClick" Click="stopAnimationClick">Stop animation</Button>
<Canvas x:Name="Grid">
<Canvas.RenderTransform>
<TransformGroup>
<RotateTransform x:Name="CanvasRotation" CenterX="300" CenterY="300" Angle="0"/>
</TransformGroup>
</Canvas.RenderTransform>
</Canvas>
<StackPanel.Triggers>
<EventTrigger RoutedEvent="Button.Click" SourceName="StartAnimationClick">
<BeginStoryboard Name="GridRotationStoryboard">
<Storyboard>
<DoubleAnimation
Storyboard.TargetName="CanvasRotation"
Storyboard.TargetProperty="Angle"
From="0.0" To="360.0"
Duration="00:00:10.00" RepeatBehavior="Forever"/>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
<!--<EventTrigger RoutedEvent="Button.Click" SourceName="StopAnimationClick">
<StopStoryboard BeginStoryboardName="GridRotationStoryboard"/>
</EventTrigger>-->
</StackPanel.Triggers>
</StackPanel>
</DockPanel>
</Window>
The commented event trigger,
<!--<EventTrigger RoutedEvent="Button.Click" SourceName="StopAnimationClick">
<StopStoryboard BeginStoryboardName="GridRotationStoryboard"/>
</EventTrigger>-->
Does indeed work as expected, that is, if I click the button, the animation stops. However, the version of the XAML above tries to replicate this functionality in C#, but this doesn't work. The click handler looks like this,
private void stopAnimationClick(object sender, RoutedEventArgs e)
{
Debug.Print("Stop animation");
// ???
}
I'm unable to control the animation object in ???, not matter what technique I try to get a handle on it. I must be plumbing the pieces incorrectly somehow, but I can't see what is wrong.

You can mimic what the EventTrigger does by calling BeginAnimation with a second argument of null:
private void stopAnimationClick(object sender, RoutedEventArgs e)
{
CanvasRotation.BeginAnimation(RotateTransform.AngleProperty, null);
}

MVVM and toggling buttons' visibility

I am using Material Design in XAML and I'm trying to create a navigation drawer. I want the drawer to slide in and out on opening/closing button click. For this purpose I've created two buttons for opening and closing, keeping one of them invisible. On top of that I have animations declared in window's resources which are used in EventTriggers section.
But apart from starting animations, I also have to hide the clicked button and show the another one.
For now I've created an event handler for both buttons and I'm keeping the code for managing visibility in code-behind as it seemed to be the easiest solution. However I'm afraid it is breaking the MVVM pattern, but on the other hand, I shouldn't bind this event to a command in a view model because the code is messing with UI-related things.
Animations and Window Triggers:
<Window.Resources>
<Storyboard x:Key="OpenMenu">
<DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="Width" Storyboard.TargetName="Menu">
<EasingDoubleKeyFrame Value="70" KeyTime="0:0:0"/>
<EasingDoubleKeyFrame Value="200" KeyTime="0:0:0.5"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
<Storyboard x:Key="CloseMenu">
<DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="Width" Storyboard.TargetName="Menu">
<EasingDoubleKeyFrame Value="200" KeyTime="0:0:0"/>
<EasingDoubleKeyFrame Value="70" KeyTime="0:0:0.5"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</Window.Resources>
<Window.Triggers>
<EventTrigger RoutedEvent="ButtonBase.Click" SourceName="OpenMenuButton">
<BeginStoryboard Storyboard="{StaticResource OpenMenu}"/>
</EventTrigger>
<EventTrigger RoutedEvent="ButtonBase.Click" SourceName="CloseMenuButton">
<BeginStoryboard Storyboard="{StaticResource CloseMenu}"/>
</EventTrigger>
</Window.Triggers>
The navigation part with buttons:
<Grid Grid.Row="1" HorizontalAlignment="Left" Width="70" Background="CornflowerBlue" x:Name="Menu">
<StackPanel>
<Grid>
<Button Style="{DynamicResource MaterialDesignFloatingActionButton}"
Background="{x:Null}" BorderBrush="{x:Null}" x:Name="OpenMenuButton" Click="ToggleMenu"
HorizontalAlignment="Right" Width="70">
<md:PackIcon Kind="Menu" Width="35" Height="35"/>
</Button>
<Button Style="{DynamicResource MaterialDesignFloatingActionButton}"
Background="{x:Null}" BorderBrush="{x:Null}" Visibility="Collapsed"
x:Name="CloseMenuButton" Click="ToggleMenu" HorizontalAlignment="Right">
<md:PackIcon Kind="ArrowLeft" Width="35" Height="35"/>
</Button>
</Grid>
</StackPanel>
</Grid>
And code-behind for managing visibility:
private void ToggleMenu(object sender, RoutedEventArgs e)
{
ToggleButtonVisibility(OpenMenuButton);
ToggleButtonVisibility(CloseMenuButton);
}
private void ToggleButtonVisibility(Button b)
{
if (b.Visibility == Visibility.Collapsed || b.Visibility == Visibility.Hidden)
b.Visibility = Visibility.Visible;
else
b.Visibility = Visibility.Collapsed;
}
Is there a way to implement this in respect to MVVM pattern (no code-behind) and to keep click actions in one place (because right now they are split in 2 parts: animation + visibility toggle)?

Add a bool flag to the viewmodel (e.g. IsAnimationStarted)
And then just bind it to buttons visibility with converter
<UserControl.Resources>
..
<local:InvertableBooleanToVisibilityConverter x:Key="bool2visible" />
..
</UserControl.Resources>
..
<Grid>
<Button Style="{DynamicResource MaterialDesignFloatingActionButton}"
Background="{x:Null}" BorderBrush="{x:Null}" x:Name="OpenMenuButton"
Visibility="{Binding IsAnimationStarted, Converter={StaticResource bool2visible}, ConverterParameter=Inverted}"
HorizontalAlignment="Right" Width="70">
<md:PackIcon Kind="Menu" Width="35" Height="35"/>
</Button>
<Button Style="{DynamicResource MaterialDesignFloatingActionButton}"
Background="{x:Null}" BorderBrush="{x:Null}" Visibility="Collapsed"
x:Name="CloseMenuButton"
Visibility="{Binding IsAnimationStarted, Converter={StaticResource bool2visible}, ConverterParameter=Normal}"
HorizontalAlignment="Right">
<md:PackIcon Kind="ArrowLeft" Width="35" Height="35"/>
</Button>
</Grid>
Visibility converter:
https://stackoverflow.com/a/2427307/6468720

EventTrigger trigger on condition

I have a event trigger.
I want it to be enabled only if condition occures
for example only if Viewmodel.IsEnabled propery is true AND EventTrigger RoutedEvent="Window.Loaded" occured
my problem is that MultiDataTrigger and MultiTriggers cannot combine Event trigger with Data Trigger.
<DataTemplate.Triggers>
<EventTrigger RoutedEvent="Window.Loaded" SourceName="NotificationWindow">
<BeginStoryboard x:Name="FadeInStoryBoard">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="NotificationWindow" From="0.01" To="1" Storyboard.TargetProperty="Opacity" Duration="0:0:2"/>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</DataTemplate.Triggers>
In other words I have a trigger to load a story board when window is loaded.
I want to be able to enable/disable this trigger per item.

You can use Blend Interactivity for WPF for accomplishing you task. I do not know your whole DataTemplate, so in my sample I will use an invented one.
Let's suppose I have a collection of Person objects and I want to start the DoubleAnimation just per Person whose property IsEnabled is true. I bind my collection to an ItemsControl and I create a "conditional" DataTemplate:
<ItemsControl ItemsSource="{Binding Path=People}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border Name="Border" BorderBrush="Gray" BorderThickness="1" CornerRadius="4" Margin="2">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Loaded">
<i:Interaction.Behaviors>
<ei:ConditionBehavior>
<ei:ConditionalExpression>
<ei:ComparisonCondition LeftOperand="{Binding IsEnabled}" RightOperand="True"/>
</ei:ConditionalExpression>
</ei:ConditionBehavior>
</i:Interaction.Behaviors>
<ei:ControlStoryboardAction ControlStoryboardOption="Play">
<ei:ControlStoryboardAction.Storyboard>
<Storyboard>
<DoubleAnimation Storyboard.TargetName="Border" From="0.01" To="1" Storyboard.TargetProperty="Opacity" Duration="0:0:2"/>
</Storyboard>
</ei:ControlStoryboardAction.Storyboard>
</ei:ControlStoryboardAction>
</i:EventTrigger>
</i:Interaction.Triggers>
<TextBlock Text="{Binding Path=Surname, Mode=OneWay}" Margin="2" />
</Border>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
Of course you have to declare those namespaces in your XAML:
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions"
The ConditionBehavior object evaluates the ComparisonCondition: if the former is true, it allows the ControlStoryboardAction to run.
I hope this small sample can give you an hint for solving your issue.

DoubleAnimation for image with Storyboard.TargetProperty="Height"

I have read How can I make an Image grow in size (give the illusion of selection) through a WPF animation? and tried to change the height of an image with a DoubleAnimation but it does not work.
<Image Name="image" Height="100" Source="http://www.online-image-editor.com/styles/2013/images/example_image.png" Stretch="None">
<Image.Resources>
<Storyboard x:Name="show">
<DoubleAnimation
Storyboard.TargetName="image"
Storyboard.TargetProperty="Height"
From="100" To="400" Duration="0:0:1"
/>
</Storyboard>
</Image.Resources>
</Image>
<Button Content="image stretch" Click="button_clicked" />
This is the button_clicked function:
private void button_clicked(object sender, RoutedEventArgs e)
{
show.Begin();
}
[edit]: Because Johan Falk´s answer I tried the above code with the Windows Phone Silverlight toolkit and it works. So the solution is to use Windows Phone Silverlight.

You just have a small error in your code, by setting Stretch="None" you don't allow the image to stretch in any direction, hence Always keeping its original size. Change Stretch to for example Uniform and it should work.
Here is the sample code I used to verify it with:
<StackPanel x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<Image Source="/Assets/ApplicationIcon.png" x:Name="testImage" Stretch="Uniform">
<Image.Resources>
<Storyboard x:Name="Animation">
<DoubleAnimation Storyboard.TargetName="testImage" Storyboard.TargetProperty="Height" From="100" To="200" Duration="0:0:1" />
</Storyboard>
</Image.Resources>
</Image>
<Button Content="Expand image" Grid.Row="1" Click="Button_Click"></Button>
</StackPanel>
private void Button_Click(object sender, RoutedEventArgs e)
{
Animation.Begin();
}

how to move UI element with storyboard?

I've worked with Opacity property in storyboard
but I cant figure it out how to move an UI element like grid stackpanel button ..... in c#?
(I am writing the storyboard in c# not in xaml )

Well, that depends on your actual layout: Do you want to animate a button in a Grid or in a Canvas (could animate the Margin property or the Canvas.Left attached property, respectively)? Do you want to animate the property itself or a transform (the latter would animate a RenderTransform - specifically a TranslateTransform). You would use the RenderTransform if you still want to refer to the "old" position.
One simple way is:
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid>
<Grid.Triggers>
<EventTrigger RoutedEvent="Grid.Loaded">
<BeginStoryboard>
<Storyboard RepeatBehavior="Forever">
<DoubleAnimation Storyboard.TargetName="myButton"
Storyboard.TargetProperty="(Canvas.Left)" From="1" To="350"
Duration="0:0:10" BeginTime="0:0:0"/>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Grid.Triggers>
<Canvas x:Name="myCanvas" Background="Yellow">
<Button x:Name="myButton" Width="100" Height="30" Canvas.Left="100" Canvas.Top="100" />
</Canvas>
</Grid>
</Window>

it would be better if you use blend for storyboard ..i have genrated a code for stackpanel movement towards right ..just check it..
you can go through this video aslo it's very good it will perfectly work in your case
<Page.Resources>
<Storyboard x:Name="Storyboard1">
<DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateX)" Storyboard.TargetName="hello">
<EasingDoubleKeyFrame KeyTime="0" Value="0"/>
<EasingDoubleKeyFrame KeyTime="0:0:0.5" Value="100"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</Page.Resources>
<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
<StackPanel Name="hello" Orientation="Vertical" HorizontalAlignment="Left" VerticalAlignment="Top" RenderTransformOrigin="0.5,0.5" >
<StackPanel.RenderTransform>
<CompositeTransform/>
</StackPanel.RenderTransform>
<TextBlock Text="hello1" FontSize="50" />
<Button Content="Button" FontSize="50" Click="Button_Click_1" />
</StackPanel>
</Grid>
and to start do this on button click..
private void Button_Click_1(object sender, RoutedEventArgs e)
{
Storyboard1.Begin();
}
for better understand just read about how to use blend..