I have a subclassed ListBox with a SelectedItemChanging dependency property that is set to a Storyboard. When the selected item is changed, I want to run this Storyboard on each item in the ListBox.
How is this possible with a single instance of Storyboard?
Storyboards can be keyed and run from multiple triggers, and it works great as long as it's set up properly. If I am understanding you correctly, you're hoping to apply the storyboard to each individual ListBoxItem. In which case, why not make a style, and on that style's triggers, fire the storyboard.
Excuse my pseudocode.
<Storyboard x:Key="MyEnterStoryboard">
<!-- Do Enter Work -->
</Storyboard>
<Storyboard x:Key="MyExitStoryboard">
<!-- Do Exit Work -->
</Storyboard>
<Style TargetType="{x:Type ListBoxItem}">
<Style.Triggers>
<Trigger Property="SelectedItemChanging" Value="True">
<Trigger.EnterActions>
<BeginStoryboard Storyboard="{StaticResource MyEnterStoryboard}"/>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard Storyboard="{StaticResource MyExitStoryboard}"/>
</Trigger.ExitActions>
</Trigger>
</Style.Triggers>
</Style>
WPF Storyboards have a Clone method. Silverlight doesn't have this but thought I'd post it just in case someone stumbles across this post looking for a WPF solution.
Related
I have created a boolean attached property in my WPF project, and I want elements with this property set to true to display a certain way, regardless of any local local values that have been set in the XAML.
From the documentation, I understand that by default, local values take precedence over both style setters and style triggers. Is it possible to create a style trigger that takes precedence over local values?
Using the technique mentioned by Erti-Chris Eelmaa in his comment on my question, I ended up creating an animation which did the trick:
<Style TargetType="{x:Type Button}">
<Style.Triggers>
<Trigger Property="my:Ext.IsReadOnly" Value="True">
<Trigger.EnterActions>
<BeginStoryboard Name="IsReadOnly">
<Storyboard>
<BooleanAnimationUsingKeyFrames Storyboard.TargetProperty="(Button.IsEnabled)" Duration="0:0:0">
<DiscreteBooleanKeyFrame Value="False" KeyTime="0:0:0" />
</BooleanAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<RemoveStoryboard BeginStoryboardName="IsReadOnly" />
</Trigger.ExitActions>
</Trigger>
</Style.Triggers>
</Style>
This takes precedence over any local value for Button.IsEnabled.
I wish to attach a time delay to a mouseover event on a WPF expander I have on my form (xaml supported by VB.NET code behind). This mouseover event essentially triggers the expansion as oppose to clicking - but I'd like a short wait before the content is expanded. So far I have not managed to find anything to solve this via the wider internet.
The current xaml code to enable the trigger is:
<Style x:Key="HoverExpander" TargetType="{x:Type Expander}">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="IsExpanded" Value="True" />
</Trigger>
</Style.Triggers>
</Style>
This style is then applied to:
<Expander Style="{StaticResource HoverExpander}"
HorizontalAlignment="Right"
ExpandDirection="Left"
Height="Auto"
Width="Auto">
<!-- Content here -->
</Expander>
Note that I've stripped out other aesthetics (such as borders, gridrefs etc for readability).
I think there should be some way to set a delay on the MouseOver Trigger but haven't had much luck finding it. This could either be set in xaml or perhaps as an event in the code behind.
I'm working on this currently, so when I find a solution I shall post it here. Grateful for any ideas meantime. Thanks!
Use an EventTrigger on the MouseOver event and a Storyboard with a BooleanAnimationUsingKeyFrames instead. In the Timeline of the Storyboard, you could have KeyFrames, so that the animation waits for some time before it affects the properties you want to change.
This was the code I settled on - based on the ideas already given:
<Style x:Key="HoverExpander" TargetType="{x:Type Expander}">
<Style.Setters>
<Setter Property="IsExpanded" Value="False"/><!-- Initially collapsed -->
</Style.Setters>
<Style.Triggers>
<!-- Impose a short delay (500ms) before expanding control -->
<EventTrigger RoutedEvent="Expander.MouseEnter">
<BeginStoryboard>
<Storyboard>
<BooleanAnimationUsingKeyFrames
Storyboard.TargetProperty="IsExpanded"
Duration="0:0:0.5">
<DiscreteBooleanKeyFrame Value="True" KeyTime="100%"/><!-- I.E. after 500ms -->
</BooleanAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
<!-- Collapse when mouse leaves control-->
<EventTrigger RoutedEvent="Expander.MouseLeave">
<BeginStoryboard>
<Storyboard>
<BooleanAnimationUsingKeyFrames
Storyboard.TargetProperty="IsExpanded"
Duration="0:0:0.1">
<DiscreteBooleanKeyFrame Value="False" KeyTime="0%"/><!-- I.E. Immediately -->
</BooleanAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Style.Triggers>
</Style>
Then apply as before. This was tested and works in .NET 4.0. Other neat tricks could be applied if you do so wish, I found the following to be quite helpful in getting ideas:
Animation Overview (MSDN)
Storyboards Overview (MSDN)
What I want to achieve is that when the mouse is hovering over the main window, all the UI elements should freeze, which I think can be done by setting Window.IsEnabled to false, and after the mouse leaves the main window, everything should be back to normal.
I've tried to define a property trigger in a style targetting Window, but it doesn't work. The code is as lollow,
<Style.Triggers>
<Trigger Property="Window.IsMouseOver" Value="True">
<Setter Property="Window.IsEnabled" Value="false"/>
</Trigger>
</Style.Triggers>
In fact this kind of property trigger wouldn't work on Grid either. Can anyone make some explanations?
I also tried to explicitly use the MouseEnter and MouseLeave events on Window, and set the disable/enable logic in the handlers. This works. I wonder if it's possible to do this in XAML?
Well to be honest I don't know why your code doesn't work, I think it goes in some kind of conflict but I don't know why
Anyway you can do it in XAML using eventsetter, It's not so elegant but it works
<Window.Triggers>
<EventTrigger RoutedEvent="Window.MouseEnter">
<BeginStoryboard>
<Storyboard Name="sb">
<BooleanAnimationUsingKeyFrames Storyboard.TargetProperty="IsEnabled" >
<BooleanKeyFrameCollection>
<DiscreteBooleanKeyFrame Value="False" KeyTime="0:0:0:1"></DiscreteBooleanKeyFrame>
</BooleanKeyFrameCollection>
</BooleanAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Window.Triggers>
I have a boolean property called IsLoginWrong, I want to then play a storyboard animation if the IsLoginWrong is true. (IsLoginWrong does an OnPropertyChanged event, so I know the binding is ok) But I'm having a hard time with the syntax. This might not even be right, but I think datatriggers can only live in Styles...
<UserControl.Style>
<Style>
<Style.Triggers>
<DataTrigger Binding="{Binding Path=IsLoginWrong}" Value="True">
<DataTrigger.EnterActions>
<BeginStoryboard Storyboard="{StaticResource LoginWrong}"/>
</DataTrigger.EnterActions>
</DataTrigger>
</Style.Triggers>
</Style>
</UserControl.Style>
But this throws an exception "A storyboard tree in a Style cannot specify a TargetName"... beause styles canno refer to items specifically.. awesome. so how do I do what I'm trying to do? (play animation if a boolean changes in mvvm)
Thanks
Within a style you cannot refer to a storyboard name. So the way I got it to work is to shove your storyboard within the actual style:
<UserControl.Style>
<Style>
<Style.Triggers>
<DataTrigger Binding="{Binding Path=IsLoginWrong}" Value="True">
<DataTrigger.EnterActions>
<BeginStoryboard>
<Storyboard>
.... PUT YOUR ACTUAL STORY BOARD IN HERE ...
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
</DataTrigger>
</Style.Triggers>
</Style>
</UserControl.Style>
Now DataTriggers can either be put into styles or control templates, so there might be a nicer way to do this with control templates. but this is what I came up with for the time being.
One option would be to start the storyboard using the VisualStateManager. The article at http://blogs.infosupport.com/blogs/alexb/archive/2010/04/02/silverlight-4-using-the-visualstatemanager-for-state-animations-with-mvvm.aspx explains how to control the current state of the VisualStateManager from the view model using an attached property.
I am trying to create a simple (I think) animation effect based on a property change in my ViewModel. I would like the target to be a specific textblock in the control template of a custom control, which inherits from Window.
From the article examples I've seen, a DataTrigger is the easiest way to accomplish this. It appears that Window.Triggers doesn't support DataTriggers, which led me to try to apply the trigger in the style. The problem I am currently having is that I can't seem to target the TextBlock (or any other child control)--what happens is which the code below is that the animation is applied to the background of the whole window.
If I leave off StoryBoard.Target completely, the effect is exactly the same.
Is this the right approach with the wrong syntax, or is there an easier way to accomplish this?
<Style x:Key="MyWindowStyle" TargetType="{x:Type Window}">
<Setter Property="Template" Value="{StaticResource MyWindowTemplate}"/>
<Style.Triggers>
<DataTrigger Binding="{Binding ChangeOccurred}" Value="True">
<DataTrigger.EnterActions>
<BeginStoryboard>
<Storyboard BeginTime="00:00:00" Duration="0:0:2" Storyboard.Target="{Binding RelativeSource={RelativeSource AncestorType=TextBlock}}"
Storyboard.TargetProperty="(Background).(SolidColorBrush.Color)">
<ColorAnimation FillBehavior="Stop" From="Black" To="Red" Duration="0:0:0.5" AutoReverse="True"/>
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
</DataTrigger>
</Style.Triggers>
</Style>
Update
Should have also mentioned that I tried to name the TextBlock and reference it via StoryBoard.TargetName (as Timores suggested), and got the error "TargetName property cannot be set on a Style Setter."
EDIT: I have overseen the fact that the TextBlock is in the ControlTemplate of your custom Window/Control. I do not think that it is possible to target a control within the ControlTemplate from a Storyboard outside of this ControlTemplate. You could however define a property on your custom Window which you then databind to your ChangeOccurred property, and then add the trigger to your ControlTemplate which will now get triggered by the custom Control's property rather than the Window's ViewModel's property (of course, indirectly it is triggered by the ViewModel because ChangeOccurred is bound to the property of the custom Window which in turn triggers the animation - uh, complex sentence, hope you understand). Is this an option? Could you follow? ;-)
Maybe some code helps:
public class MyCustomWindow : Window
{
public static readonly DependencyProperty ChangeOccurred2 = DependencyProperty.Register(...);
public bool ChangeOccurred2 { ... }
// ...
}
And some XAML:
<local:MyCustomWindow ChangeOccurred2="{Binding ChangeOccurred}" ... >
<!-- Your content here... -->
</local:MyCustomWindow>
<!-- Somewhere else (whereever your ControlTemplate is defined) -->
<ControlTemplate TargetType="{x:Type local:MyCustomWindow}">
<!-- your template here -->
<ControlTemplate.Triggers>
<Trigger Property="ChangeOccurred2" Value="True">
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard BeginTime="00:00:00" Duration="0:0:2"
Storyboard.TargetName="txtWhatever"
Storyboard.TargetProperty="(Background).(SolidColorBrush.Color)">
<ColorAnimation FillBehavior="Stop"
From="Black" To="Red"
Duration="0:0:0.5"
AutoReverse="True"/>
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
Note: I named the Window's property ChangeOccurred2 because I wanted it to be distinguishable from the ViewModel's ChangeOccurred property. Of course, you should choose a better name for this property. However, I am missing the background for such a decision.
My old answer:
So, you want to animate a TextBlock which is in the content of a (custom) Window?!
Why do you want to set the style on the Window, and not on the TextBlock itself? Maybe you should try something like this (did not test this!):
<local:MyCustomWindow ... >
<!-- ... -->
<TextBlock x:Name="textBlockAnimated" ... >
<TextBlock.Style>
<Style TargetType="{x:Type TextBlock}">
<Style.Triggers>
<DataTrigger Binding="{Binding ChangeOccurred}" Value="True">
<DataTrigger.EnterActions>
<BeginStoryboard>
<Storyboard BeginTime="00:00:00" Duration="0:0:2"
Storyboard.TargetProperty="(Background).(SolidColorBrush.Color)">
<ColorAnimation FillBehavior="Stop"
From="Black" To="Red"
Duration="0:0:0.5"
AutoReverse="True"/>
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
<!-- ... -->
</local:MyCustomWindow>
The {Binding ChangeOccurred} might not be sufficient. You might have to add a DataContext to the TextBlock, or add a RelativeSource or something.
Is the TextBlock in the MyWindowTemplate ?
If so, give the TextBlock a name and use Storyboard.TargetName to reference it.
See another question in SO