WPF: Button ControlTemplate + space = exception?
I put together a template in Expression Blend for a button and it works fine - until I navigate to it and hit the spacebar. I am getting the following error:
InvalidOperationException Property [Unknown] 'does not point to a DependencyObject in path' (0). (1). [0]. (2) '.
The code looks like this:
<ControlTemplate x:Key="EmailButton" TargetType="{x:Type Button}">
<ControlTemplate.Resources>
<Storyboard x:Key="MouseOverStoryboard">
<ColorAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="border" Storyboard.TargetProperty="(Panel.Background).(GradientBrush.GradientStops)[0].(GradientStop.Color)">
<SplineColorKeyFrame KeyTime="00:00:00.4000000" Value="#FF55679E"/>
</ColorAnimationUsingKeyFrames>
</Storyboard>
<Storyboard x:Key="UnMouseOverStoryboard">
<ColorAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="border" Storyboard.TargetProperty="(Panel.Background).(GradientBrush.GradientStops)[0].(GradientStop.Color)">
<SplineColorKeyFrame KeyTime="00:00:00.4000000" Value="#FF92A2D3"/>
</ColorAnimationUsingKeyFrames>
</Storyboard>
</ControlTemplate.Resources>
<Border x:Name="border" BorderBrush="#FF000000" BorderThickness="2,2,2,2" CornerRadius="4,4,4,4">
<Border.Background>
<LinearGradientBrush EndPoint="0.47,-0.01" StartPoint="0.47,0.808">
<GradientStop Color="#FF92A2D3" Offset="0"/>
<GradientStop Color="#FFFFFFFF" Offset="1"/>
</LinearGradientBrush>
</Border.Background>
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" Margin="{TemplateBinding Padding}"/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsPressed" Value="True">
<Setter Property="Background" TargetName="border" Value="#FF92A2D3"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Trigger.EnterActions>
<BeginStoryboard x:Name="MouseOverStoryboard_BeginStoryboard" Storyboard="{StaticResource MouseOverStoryboard}"/>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard x:Name="UnMouseOverStoryboard_BeginStoryboard" Storyboard="{StaticResource UnMouseOverStoryboard}"/>
</Trigger.ExitActions>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
It seems that either MouseOverStoryboard or UnMouseOverStoryboard is fired (the path mentioned in the error seems to match the TargetProperty). I'm not sure why I either fired when I hit the spacebar though ... Any suggestions?
EDIT: Thanks to Ryan Versaw, I tried the following, which now prevents the spacebar from being pressed when throwing an exception:
<Trigger Property="IsPressed" Value="True">
<Setter Property="Background" TargetName="border">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FF92A2D3" Offset="0"/>
<GradientStop Color="#FF92A2D3" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
</Trigger>
The brush type now remains consistent (LinearGradientBrush), and there is always 0 available GradientStop.
I am still interested in knowing one more thing: what is the best to solve this problem, given that this sorta is like a hack (eg: added / animated third gradient stop, then a third GradientStop must be added when IsPressed == True) ...
Thanks for the suggestions! Hope this helps someone else too.
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I'm not sure what the optimal solution would be, but I found one that works.
Create LinearGradientBrush
in your resources:
<LinearGradientBrush x:Key="solidBrush">
<GradientStop Color="#FF92A2D3"/>
</LinearGradientBrush>
Modify the trigger IsPressed
as follows (changes only Value
):
<Trigger Property="IsPressed" Value="True">
<Setter Property="Background" TargetName="border" Value="{StaticResource solidBrush}"/>
</Trigger>
This should change the entire background to a new one (which it also is LinearGradientBrush
).
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It looks like your IsPressed Trigger Setter trigger is trying to assign a color value (# FF92A2D3) to the Background property of your border. However, the background property of your border contains a linear gradient brush, not a solid color brush. However, this is only a glance.
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