一个用户控件对另一用户控件的可见性

Question

private void Button_Click(object sender, RoutedEventArgs e)
        {
            int selectedValue = (int)comboSelection.SelectedValue;
            if (selectedValue == 8)
            {
                EightTiles et = new EightTiles();
                this.Visibility = Visibility.Collapsed;
                et.Visibility = Visibility.Visible;
            }
        }

My target is when the combo box selection is equal to 8 then click the button, current usercontrol get collapsed and next usercontrol(EightTiles) get visible. But my problem is when i click the button it shows a blank page, next user control page doesn't showed, what is the problem and how i do to solve it.. Thanks

Answer 1

your problem is that et goes out of scope, so after the function is doesn't exist anymore. you need to create it "outside" in a scope where it will still exist before and after that function.

So for example if there's a class called Application and that class holds the current control that your Button_click is attached to, you need to create the other control there too. Or at least the et variable if you don't want to create the EightTiles until you need it.

Answer 2

Plase both these controls as content of a main content control to xaml, and manage the second control visibility based on trigger of the first control. Here what I can suggest you: 1. XAML:

<Window x:Class="SoDataGridProjectsHelpAttempt.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:soDataGridProjectsHelpAttempt="clr-namespace:SoDataGridProjectsHelpAttempt"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <ContentControl >
        <ContentControl.ContentTemplate>
            <DataTemplate>
                <Grid>
                    <soDataGridProjectsHelpAttempt:MainSubControl x:Name="MainSubControl" Visibility="Visible"/>
                    <soDataGridProjectsHelpAttempt:SubSubControl x:Name="SubSubControl" Visibility="Collapsed"/>
                </Grid>
                <DataTemplate.Triggers>
                    <Trigger Property="Control.Visibility" Value="Collapsed" SourceName="MainSubControl">
                        <Setter TargetName="SubSubControl" Property="Visibility" Value="Visible"></Setter>
                    </Trigger>
                </DataTemplate.Triggers>
            </DataTemplate>
        </ContentControl.ContentTemplate>
    </ContentControl>
</Grid>

2. MainSubControl:

<UserControl x:Class="SoDataGridProjectsHelpAttempt.MainSubControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:soDataGridProjectsHelpAttempt="clr-namespace:SoDataGridProjectsHelpAttempt"
         xmlns:collections="clr-namespace:System.Collections;assembly=mscorlib"
         xmlns:system="clr-namespace:System;assembly=mscorlib"
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300" Visibility="{Binding IsControlVisible, Converter={StaticResource Bol2VisibilityConverter}, UpdateSourceTrigger=PropertyChanged}">
<UserControl.Resources>
    <x:Array Type="system:Int32" x:Key="DecimalsArray">
        <system:Int32>7</system:Int32>
        <system:Int32>5</system:Int32>
        <system:Int32>3</system:Int32>
        <system:Int32>8</system:Int32>
    </x:Array>
</UserControl.Resources>
<UserControl.DataContext>
    <soDataGridProjectsHelpAttempt:MainSubViewModel/>
</UserControl.DataContext>
<StackPanel>
    <ComboBox ItemsSource="{StaticResource DecimalsArray}" 
              Width="Auto" 
              SelectedItem="{Binding SelectedComboItem}"/>
    <Button Command="{Binding Command}">Press me!!!</Button>
</StackPanel>

3. MainSubControl ViewModel:

    public class MainSubViewModel : BaseObservableObject
{
    private int _selectedComboItem;
    private ICommand _command;
    private bool _isControlVisible;

    public MainSubViewModel()
    {
        IsControlVisible = true;
    }

    public ICommand Command
    {
        get { return _command ?? (_command = new RelayCommand(CommandMethod)); }
    }

    private void CommandMethod()
    {
        if (SelectedComboItem == 8)
            IsControlVisible = false;
    }

    public bool IsControlVisible
    {
        get { return _isControlVisible; }
        set
        {
            _isControlVisible = value;
            OnPropertyChanged();
        }
    }

    public int SelectedComboItem
    {
        get { return _selectedComboItem; }
        set
        {
            _selectedComboItem = value;
            OnPropertyChanged();
        }
    }
}

4. SecondSubControl:

<UserControl x:Class="SoDataGridProjectsHelpAttempt.SubSubControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300">
<Grid>
    <Image Source="2014_8_27_Bing_en-AU.jpg" Margin="50"></Image>
</Grid>

5. App.xaml (put into Application.Resources):

<BooleanToVisibilityConverter x:Key="Bol2VisibilityConverter" />

regards,