Usage of VisualStateManager to Define User Interface in Silverlight 3
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by Sergey Zwezdin
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Definition of states on the basis of VisualStateManager

Let us consider an implementation of a described above approach based on a Button control template creation. First, it is necessary to redefine a control element template. It can be done in a style or directly with help of a property setting. We will define a template through the direct setting of a Template property.

Listing 1 - Simple button definition

<Button Content="Button">
      <Button.Template>
            <ControlTemplate TargetType="Button">
                  <Grid />
            </ControlTemplate>
      </Button.Template>
</Button>

As a result of this definition, we get an empty button. So it is necessary to fill it with content.

Listing 2 - Simple button definition with contents

<Button Content="Button">
      <Button.Template>
            <ControlTemplate TargetType="Button">
                  <Grid>
                        <Border CornerRadius="3" BorderBrush="Black" BorderThickness="1" 
Background="Silver" />
                        
                        <ContentPresenter VerticalAlignment="Center" HorizontalAlignment="Center" />
                  </Grid>
            </ControlTemplate>
      </Button.Template>
</Button>   

Thanks to this definition the button has gotten borders and begun to display its content. However, in the given template there is no dynamics. If we hover the mouse cursor to the button or press it, nothing will change. It is easy to be changed. For example, in the simplest case it is possible to change a button background. For that end, if adding some control elements, it will be displayed in various states.

Listing 3 - The button definition with contents and additional layout

<Button Content="Button">
      <Button.Template>
            <ControlTemplate TargetType="Button">
                  <Grid>
                        <Border Name="NormalBackground" CornerRadius="3" 
BorderBrush="Black" BorderThickness="1" Background="Silver" />
                        <Border Name="HoverBackground" Opacity="0" 
CornerRadius="3" BorderBrush="Black" BorderThickness="3" Background="Gray" />
                        
                        <ContentPresenter VerticalAlignment="Center"
HorizontalAlignment="Center" />
                  </Grid>
            </ControlTemplate>
      </Button.Template>
</Button>   

Pay attention to the fact "HoverBackground" control element is hidden in this case (property Opacity equals 0). Our goal is to display it at the moment of the mouse cursor hovering over the button and to hide in the opposite situation. For this purpose it is necessary to define VisualStateManager object which will execute all work.

Listing 4 - The button definition with VisualStateManager

<Button Content="Button">
      <Button.Template>
            <ControlTemplate TargetType="Button">
                  <Grid>
                        <VisualStateManager.VisualStateGroups>
                              <VisualStateGroup x:Name="CommonStates">
                                    <VisualState x:Name="Normal">
                                          <Storyboard>
                                                <DoubleAnimation To="1" 
Duration="0:00:00.5" Storyboard.TargetName="NormalBackground" Storyboard.TargetProperty="Opacity"/>
                                                <DoubleAnimation To="0" 
Duration="0:00:00.5" Storyboard.TargetName="HoverBackground" Storyboard.TargetProperty="Opacity"/>
                                          </Storyboard>
                                    </VisualState>
                                    <VisualState x:Name="MouseOver">
                                          <Storyboard>
                                                <DoubleAnimation To="0" 
Duration="0:00:00.5" Storyboard.TargetName="NormalBackground" Storyboard.TargetProperty="Opacity"/>
                                                <DoubleAnimation To="1" 
Duration="0:00:00.5" Storyboard.TargetName="HoverBackground" Storyboard.TargetProperty="Opacity"/>
                                          </Storyboard>
                                    </VisualState>
                              </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>
                        
                        <Border Name="NormalBackground" CornerRadius="3" 
BorderBrush="Black" BorderThickness="1" Background="Silver" />
                        <Border Name="HoverBackground" Opacity="0"
CornerRadius="3" BorderBrush="Black" BorderThickness="3" Background="Gray" />
                        
                        <ContentPresenter VerticalAlignment="Center" 
HorizontalAlignment="Center" />
                  </Grid>
            </ControlTemplate>
      </Button.Template>
</Button>   

There is a similar way to manage a control element appearance for several states. For example, it is possible to add to the button a representation of state "pressed."

Listing 5 - The button definition with VisualStateManager which describes three states

<Button Content="Button">
      <Button.Template>
            <ControlTemplate TargetType="Button">
                  <Grid>
                        <VisualStateManager.VisualStateGroups>
                              <VisualStateGroup x:Name="CommonStates">
                                    <VisualState x:Name="Normal">
                                          <Storyboard>
                                                <DoubleAnimation To="1" 
Duration="0:00:00.5" Storyboard.TargetName="NormalBackground" Storyboard.TargetProperty="Opacity"/>
                                                <DoubleAnimation To="0" 
Duration="0:00:00.5" Storyboard.TargetName="HoverBackground" Storyboard.TargetProperty="Opacity"/>
                                                <DoubleAnimation To="0" 
Duration="0:00:00.5" Storyboard.TargetName="PressedBackground" Storyboard.TargetProperty="Opacity"/>
                                          </Storyboard>
                                    </VisualState>
                                    <VisualState x:Name="MouseOver">
                                          <Storyboard>
                                                <DoubleAnimation To="0"
Duration="0:00:00.5" Storyboard.TargetName="NormalBackground" Storyboard.TargetProperty="Opacity"/>
                                                <DoubleAnimation To="1" Duration="0:00:00.5" 
Storyboard.TargetName="HoverBackground" 
Storyboard.TargetProperty="Opacity"/>
                                                <DoubleAnimation To="0" Duration="0:00:00.5" 
Storyboard.TargetName="PressedBackground"
Storyboard.TargetProperty="Opacity"/>
                                          </Storyboard>
                                    </VisualState>
                                    <VisualState x:Name="Pressed">
                                          <Storyboard>
                                                <DoubleAnimation To="0"
Duration="0:00:00.5" Storyboard.TargetName="NormalBackground" Storyboard.TargetProperty="Opacity"/>
                                                <DoubleAnimation To="0"
Duration="0:00:00.5" Storyboard.TargetName="HoverBackground" Storyboard.TargetProperty="Opacity"/>
                                                <DoubleAnimation To="1"
Duration="0:00:00.5" Storyboard.TargetName="PressedBackground"
Storyboard.TargetProperty="Opacity"/>
                                          </Storyboard>
                                    </VisualState>
                              </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>
                        
                        <Border Name="NormalBackground" CornerRadius="3"
BorderBrush="Black" BorderThickness="1" Background="Silver" />
                        <Border Name="HoverBackground" Opacity="0"
CornerRadius="3" BorderBrush="Black" BorderThickness="3" Background="Gray" />
                        <Border Name="PressedBackground" Opacity="0"
CornerRadius="8" BorderBrush="Black" BorderThickness="1" Background="Red" />
                        
                        <ContentPresenter VerticalAlignment="Center" HorizontalAlignment="Center" />
                  </Grid>
            </ControlTemplate>
      </Button.Template>
</Button>

As a result, the given button will look differently in three various states - normal, pressed and hovered.


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User Comments

Title: Nice article   
Name: bala
Date: 2010-12-31 3:19:59 AM
Comment:
nice article, inspired to do






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