ContentControl switch between two buttons

Question

I've been banging my head over this all night. All I want to do is have a content control that can switch between showing two different buttons according to a boolean in the ViewModel.

Basically I have a task running in the background with a cancel button. Once you hit cancel and the task stops, the cancel button should change to a back button. These are two separate button elements, not just changing a single button's properties. I'm using MahApps TransitioningContentControl so I want to be able to use the transitions.

I would be amazing if this could mostly be done all in XAML. I really don't want to have to add a bunch of boilerplate code for what should be a simple thing.

Edit: Here's the snippet of code. There isn't much because I just deleted everything that wasn't working.

<Controls:TransitioningContentControl x:Name="CancelBackButtonControl" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80">
    <Canvas>
        <Button x:Name="CancelButton" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Style="{DynamicResource MetroCircleButtonStyle}" Height="80" IsCancel="True" Content="{StaticResource appbar_close}" BorderBrush="Black" Command="{Binding CancelCommand}"/>
        <Button x:Name="GoBackButton" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Style="{DynamicResource MetroCircleButtonStyle}" Height="80" IsCancel="True" Content="{StaticResource appbar_arrow_left}" BorderBrush="Black" Command="{Binding GoBackCommand}"/>
    </Canvas>
</Controls:TransitioningContentControl>

Answer 1

You can implement such functionality with just one Button (e.g. declared in XAML as Name="btnCancel") and simple code snippet in C# code-behind using Lambda-style event subscription like:

    btnCancel.Click+=(s,e)=>{
    if (btnCancel.Text=="Cancel")
    {
      // SOME CODE CORRESPONDING TO "CANCEL" CLICK EVENT
      btnCancel.Text ="GoBack"
    }
    else 
    {
      // CORRESPONDING TO "GoBack" CLICK EVENT
      btnCancel.Text ="Cancel"
    }
}

In case you want to use some graphic content (images) on the Button, then use Tag property of that Button instead of Text and also programmatically switch between images.

Couple other considerations: the business logic you have described could be implemented in XAML using DataTriggers (as other folks did), but instead of writing megaton of XAML for 2-Buttons solutions it would be reasonable to implement a single-button solution, either like this one, or using .NET ToggleButton Class (re: https://msdn.microsoft.com/en-us/library/system.windows.controls.primitives.togglebutton%28v=vs.110%29.aspx); also, it could be a CheckBox control just properly styled.

In any way, you most likely will need the event handlers to do some actual job in addition to just changing the visual state of the Button, so that compact Lambda-style event subscription would be handy.

Hope this may help. Best regards,

Answer 2

Since you're asking for a XAML only way to switch the button in a content control based on a ViewModel property, how about this:

First define button style to route both buttons to the same event:

<Style x:Key="buttonClickButton" TargetType="Button">
    <EventSetter Event="Click"  Handler="Button_Click"/>
</Style>

Then define your content control style with a data trigger switching the content based on a ViewModel property called "IsCancelButton" (bool):

<Style x:Key="ButtonSwitchContentCtrl" TargetType="ContentControl">
    <Style.Triggers>
        <DataTrigger Binding="{Binding IsCancelButton}" Value="True">
            <Setter Property="Content">
                <Setter.Value>
                    <Button x:Name="CancelButton" Style="{StaticResource buttonClickButton}" 
                            HorizontalAlignment="Left" VerticalAlignment="Top" 
                            Width="80"  Height="80" IsCancel="True" Content="Cancel Button" BorderBrush="Black" />
                </Setter.Value>
            </Setter>
        </DataTrigger>
        <DataTrigger Binding="{Binding IsCancelButton}" Value="False">
            <Setter Property="Content">
                <Setter.Value>
                    <Button x:Name="GoBackButton" Style="{StaticResource buttonClickButton}" 
                            HorizontalAlignment="Left" VerticalAlignment="Top" 
                            Width="80"  Height="80" IsCancel="True" Content="Go Back Button" BorderBrush="Black" />
                </Setter.Value>
            </Setter>
        </DataTrigger>
    </Style.Triggers>
</Style>

Then make your button(s) appear like so:

<ContentControl Style="{StaticResource ButtonSwitchContentCtrl}"/>

Answer 3

There are a staggering amount of ways to accomplish this (that's the beauty of WPF); however, in my personal opinion, you would be working less "against the grain" if you simply use a control that derives from the ToggleButton, such as RadioButton, especially since you want it to be done all in XAML. An important thing is not to think of any of the controls by their visuals, but by how they function. I've done some incredible things with RadioButton before, so that's the first thing I'll demonstrate; however, the regular button approach is included in the second half of this answer.

Here are the complete examples of both approaches (RadioButton and Button), done completely in XAML:

Preview:

Code:

<Window x:Class="Sample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <Style TargetType="{x:Type RadioButton}" x:Key="FlatRadioButtonStyle">
            <Setter Property="Width" Value="100"/>
            <Setter Property="Background" Value="#FF346FD6"/>
            <Setter Property="Foreground" Value="White"/>
            <Setter Property="Padding" Value="5,2,5,3"/>
            <Setter Property="VerticalAlignment" Value="Center"/>
            <Setter Property="HorizontalAlignment" Value="Center"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type RadioButton}">
                        <Border Background="{TemplateBinding Background}"
                                Width="{TemplateBinding Width}"
                                BorderBrush="{TemplateBinding BorderBrush}"
                                BorderThickness="{TemplateBinding BorderThickness}"
                                VerticalAlignment="{TemplateBinding VerticalAlignment}"
                                HorizontalAlignment="{TemplateBinding HorizontalAlignment}">
                            <ContentPresenter Content="{TemplateBinding Content}"
                                              Margin="{TemplateBinding Padding}"
                                              HorizontalAlignment="Center"
                                              VerticalAlignment="Center"/>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsMouseOver" Value="True">
                                <Setter Property="Background" Value="#FF6696E9"/>
                            </Trigger>
                            <Trigger Property="IsChecked" Value="True">
                                <Setter Property="Visibility" Value="Collapsed"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Window.Resources>

    <Grid>
        <RadioButton x:Name="BackButton" Content="Back">
            <RadioButton.Style>
                <Style TargetType="{x:Type RadioButton}" BasedOn="{StaticResource FlatRadioButtonStyle}">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding IsChecked, ElementName=CancelButton}" Value="True">
                            <Setter Property="Visibility" Value="Visible"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </RadioButton.Style>
        </RadioButton>
        <RadioButton x:Name="CancelButton" Content="Cancel" IsChecked="True">
            <RadioButton.Style>
                <Style TargetType="{x:Type RadioButton}" BasedOn="{StaticResource FlatRadioButtonStyle}">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding IsChecked, ElementName=BackButton}" Value="True">
                            <Setter Property="Visibility" Value="Visible"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </RadioButton.Style>
        </RadioButton>
    </Grid>
</Window>

Most of the resource style code is visual styling and templating, focused on making radio buttons look like regular buttons, so it's not of great importance. The areas we'll focus on are Triggers. You'll notice that in the resource style, I ensure that when a RadioButton gets checked, it collapses. However, in the local style of each button, I ensure that when the other RadioButton gets checked, it makes the current RadioButton visible. This has to be done in the local style, since we need to pass the ElementName into the Binding. So, when a RadioButton gets checked, it collapses and makes the other RadioButton visible. You'll also note that I check the button I wish to hide by default. Obviously, you can wire that up with bindings.

Similar approaches may be applied to regular buttons:

Preview:

Code:

<Window x:Class="Sample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">   
    <Window.Resources>
        <Style TargetType="{x:Type Button}" x:Key="ToggleButtonStyle">
            <Setter Property="Width" Value="100"/>
            <Setter Property="HorizontalAlignment" Value="Center"/>
            <Setter Property="VerticalAlignment" Value="Center"/>
            <Style.Triggers>
                <Trigger Property="IsFocused" Value="True">
                    <Setter Property="Visibility" Value="Collapsed"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid>
        <Button x:Name="CancelButton" Content="Cancel">
            <Button.Style>
                <Style TargetType="{x:Type Button}" BasedOn="{StaticResource ToggleButtonStyle}">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding IsFocused, ElementName=BackButton}" Value="True">
                            <Setter Property="Visibility" Value="Visible"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </Button.Style>
        </Button>
        <Button x:Name="BackButton" Content="Back">
            <Button.Style>
                <Style TargetType="{x:Type Button}" BasedOn="{StaticResource ToggleButtonStyle}">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding IsFocused, ElementName=CancelButton}" Value="True">
                            <Setter Property="Visibility" Value="Visible"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </Button.Style>
        </Button>
    </Grid>
</Window>

Here, instead of IsChecked, I'm working with IsFocused. You may accomplish a similar thing by working with the EventTrigger and Click event... but, there's more work. IsPressed may appear like a good candidate, but the problem is that once you press the button, the other one will appear almost instantaneously, and that one will have IsPressed set to true almost instantaneously. So, you'll end up with this cyclic behavior where it seems like nothing is happening. Note that I use Grid to place these buttons on top of each other, with the the one I want to be visible by default at the top, that way I don't have to worry about default visibility or focus. However, you may use any other panel, just set the Visibility of the button you want to hide by default to Collapsed.

If you don't want to work with multiple controls (two buttons in this case), you may also set the Content property of a button based on a condition through DataTrigger to display different text. You just have to ensure that you handle the Command appropriately.