Using VisualStateManager to start and stop Storyboards

问题

I have an animation that animates a Canvas by turning it 360 degrees indefinitely (it basically spins). What I want is for this animation to start when the control is shown and then stop when the control is hidden. I figured I could tie this in, somehow, to the VisualStateManager. I have seen an example of fading in and out controls here which could work but I just dont know how to use VSM to start and stop the storyboard

<Canvas.Resources>
    <Storyboard x:Name="spinnerBoard">
        <DoubleAnimation
            Storyboard.TargetName="SpinnerRotate"
            Storyboard.TargetProperty="Angle"
            From="0" To="360" Duration="0:0:01.3"
            RepeatBehavior="Forever" />
    </Storyboard>
</Canvas.Resources>

<Canvas.RenderTransform>
    <RotateTransform x:Name="SpinnerRotate" Angle="0" />
</Canvas.RenderTransform>

Example VSM

<VisualState x:Name="Show">
    <Storyboard>
        <!-- Start the story board here -->
    </Storyboard>
</VisualState>
<VisualState x:Name="Hide">
    <Storyboard>
        <!-- Stop the story board here -->
    </Storyboard>
</VisualState>

回答1:

A global answer of your different questions :
ExtendedVisualStateManager.GoToElementState returns false in Silverlight
Default binding to UserControl for custom DP

You can do something like this :

Use a template control that extend ContentControl to play with IsEnabled of content (prevent action during waiting) ;
Create a DP IsWaiting that switch your control visual state ;
Create the two states in XAML : Use DoubleAnimation with RepeatBehavior="Forever"

After you can add a overlay and a Waiting message dependency property like the busy indicator control...

I use a picture for the Waiting visual part but you can use a canvas, grid etc...

[TemplateVisualState(GroupName = "WaitGroup", Name = WaitSpinner.IsWaitingStateName)]
[TemplateVisualState(GroupName = "WaitGroup", Name = WaitSpinner.NotWaitingStateName)]
public class WaitSpinner : ContentControl
{
    #region States names
    internal const String IsWaitingStateName = "IsWaitingState";
    internal const String NotWaitingStateName = "NotWaitingState";
    #endregion States names

    public bool IsWaiting
    {
        get { return (bool)GetValue(IsWaitingProperty); }
        set { SetValue(IsWaitingProperty, value); }
    }

    public static readonly DependencyProperty IsWaitingProperty =
        DependencyProperty.Register("IsWaiting", typeof(bool), typeof(WaitSpinner), new PropertyMetadata(false, OnIsWaitingPropertyChanged));

    private static void OnIsWaitingPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        WaitSpinner waitSpinner = (WaitSpinner)sender;
        waitSpinner.ChangeVisualState(true);
    }

    public WaitSpinner()
    {
        DefaultStyleKey = typeof(WaitSpinner);
    }

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();
        ChangeVisualState(false);
    }

    protected virtual void ChangeVisualState(bool useTransitions)
    {
        VisualStateManager.GoToState(this, IsWaiting ? IsWaitingStateName : NotWaitingStateName, useTransitions);
    }
}

Xaml :

<VisualStateGroup x:Name="WaitGroup">
    <VisualState x:Name="NotWaitingState" >
        <Storyboard>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(Control.IsEnabled)" Storyboard.TargetName="content">
                <DiscreteObjectKeyFrame KeyTime="0">
                    <DiscreteObjectKeyFrame.Value>
                        <System:Boolean>True</System:Boolean>
                    </DiscreteObjectKeyFrame.Value>
                </DiscreteObjectKeyFrame>
            </ObjectAnimationUsingKeyFrames>
        </Storyboard>
    </VisualState>
    <VisualState x:Name="IsWaitingState">
        <Storyboard>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="WaitPart">
                <DiscreteObjectKeyFrame KeyTime="0:0:0.200" Value="Visible"/>
            </ObjectAnimationUsingKeyFrames>
            <DoubleAnimation Storyboard.TargetProperty="(UIElement.RenderTransform).(RotateTransform.Angle)" Storyboard.TargetName="WaitPart" To="360" RepeatBehavior="Forever" Duration="0:0:1" />
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(Control.IsEnabled)" Storyboard.TargetName="content">
                <DiscreteObjectKeyFrame KeyTime="0">
                    <DiscreteObjectKeyFrame.Value>
                        <System:Boolean>False</System:Boolean>
                    </DiscreteObjectKeyFrame.Value>
                </DiscreteObjectKeyFrame>
            </ObjectAnimationUsingKeyFrames>
        </Storyboard>
    </VisualState>
</VisualStateGroup>
<!-- ............. -->
<ContentControl
    IsTabStop="False"
    x:Name="content"
    Content="{TemplateBinding Content}"
    ContentTemplate="{TemplateBinding ContentTemplate}"
    HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
    VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
    Foreground="{TemplateBinding Foreground}"
    ScrollViewer.HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
    ScrollViewer.VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}"/>
<Image Source="CirclePicture.png"
    x:Name="WaitPart"
    RenderTransformOrigin="0.5,0.5"
    Width="16"
    Height="16"
    Visibility="Collapsed"
    IsHitTestVisible="False">
    <Image.RenderTransform>
        <RotateTransform  />
    </Image.RenderTransform>
</Image>

来源：https://stackoverflow.com/questions/17741799/using-visualstatemanager-to-start-and-stop-storyboards

标签

silverlight

xaml

visualstatemanager