CODEWITHSUNDEEP
c#wpfbuttonstyles
el-nino
el-nino

Reputation: 399

WPF Button Style Template IsEnabled

i based my application on this example

i need my own button-style (without mouseover animations etc.), so i made this in the app.xaml:

<Style TargetType="Button" BasedOn="{StaticResource {x:Type Button}}">
        <Setter Property="SnapsToDevicePixels" Value="true"/>
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Button">
                    <Border x:Name="Border"
                        CornerRadius="2" BorderThickness="1"
                        Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}">
                        <ContentPresenter Margin="2" HorizontalAlignment="Center" VerticalAlignment="Center" RecognizesAccessKey="True"/>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}" />
                            <Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource DisabledBorderBrush}" />
                            <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

my button: <Button IsEnabled="true"/>

now if i change the button to <Button IsEnabled="false"/> my app crashes at the start with an error like: "{DependencyProperty.UnsetValue}" is not a valid value for property "BorderBrush".

what am i doing wrong?

Upvotes: 1

Views: 3059

Answers (1)

David E
David E

Reputation: 1444

It has to do with your static reference.

In particular, XAML parsing is very touchy on order - you have to make sure that a brush with x:Key="DisabledForegroundBrush" is referenced before the parser gets to the line in the above style - even if your style above is in the same file as the DisabledForegroundBrush.

If you don't have a brush yet for the DisabledForegroundBrush, you can either remove the line referencing it in the above code if you don't require it, or, if you want it, you can create one as follows:

<SolidColorBrush x:Key="DisabledForegroundBrush" Color="Red" />

Where you can choose the color as appropriate. Alternatively, you can choose some other kind of brush here: http://msdn.microsoft.com/en-us/library/aa970904(v=vs.110).aspx

If you have a brush you'd like to use already, then if you could provide a little more information as to where the brush is in the code base (eg is it in a resource dictionary?) and where the DisabledForegroundBrush brush is, this might help me pinpoint an actual solution / best way of ensuring the brush is referenced.

Note: an alternative if you can't ensure that DisabledForegroundBrush is parsed first is to change the StaticResource to a DynamicResource, but this isn't recommended unless the resource's link might actually change at run time (see What's the difference between StaticResource and DynamicResource in WPF? )

An easier solution:

If you just want to hard-code the style in, instead of reference the foreground brush externally, then you could change the line:

<Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>

to:

<Setter Property="Foreground" Value="[SOME COLOR]"/>

To get rid of the need to create a separate brush object for your font.

Upvotes: 1

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