WPF Addict

Synchronize items Width in WrapPanel

17/01/2019 admin Aucun commentaire

if you want to have the same width size for each items in WrapPanel (in in ListBox for sample)
you can use Grid.IsSharedSizeScope= »True » like this

<Window.Resources>
        <DataTemplate DataType="{x:Type local:ColorX}">
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"
                                      SharedSizeGroup="ColumnSize" />
                </Grid.ColumnDefinitions>
                <StackPanel Orientation="Horizontal"
                            Margin="2">
                    <Rectangle Width="40"
                               Height="25"
                               Fill="{Binding Brush}"
                               Stroke="Black" />
                    <TextBox Text="{Binding Name}"
                             IsReadOnly="true"
                             Background="Transparent"
                             VerticalAlignment="Center"
                             BorderThickness="0"
                             Margin="4 0 4 0" />
                </StackPanel>
            </Grid>
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <ListBox ItemsSource="{Binding .}"
                 Margin="10"
                 BorderThickness="1"
                 BorderBrush="RoyalBlue"
                 ScrollViewer.HorizontalScrollBarVisibility="Disabled">
            <ListBox.ItemsPanel>
                <ItemsPanelTemplate>
                    <WrapPanel IsItemsHost="True"
                               Grid.IsSharedSizeScope="True" />
                </ItemsPanelTemplate>
            </ListBox.ItemsPanel>
        </ListBox>
    </Grid>

<Window.Resources>

<Grid>

<Grid.ColumnDefinitions>

<ColumnDefinition Width="Auto"

SharedSizeGroup="ColumnSize" />

</Grid.ColumnDefinitions>

<StackPanel Orientation="Horizontal"

Margin="2">

<Rectangle Width="40"

Height="25"

Fill="{Binding Brush}"

Stroke="Black" />

<TextBox Text="{Binding Name}"

IsReadOnly="true"

Background="Transparent"

VerticalAlignment="Center"

BorderThickness="0"

Margin="4 0 4 0" />

</StackPanel>

</Grid>

</DataTemplate>

</Window.Resources>

<Grid>

<ListBox ItemsSource="{Binding .}"

Margin="10"

BorderThickness="1"

BorderBrush="RoyalBlue"

ScrollViewer.HorizontalScrollBarVisibility="Disabled">

<ListBox.ItemsPanel>

<WrapPanel IsItemsHost="True"

Grid.IsSharedSizeScope="True" />

</ItemsPanelTemplate>

</ListBox.ItemsPanel>

</ListBox>

</Grid>

Categories: Non classé Tags:

FallbackValue for Command

10/01/2019 admin Aucun commentaire

When you try to connect an MVVM command, it must be better to have a fallbackvalue if binding not release
a null static command return false is the solution for showed that the binding cannot be set (and not allow command)

for sample if i have the command : CloseCommand in Selected in my MVVM
when selected is set to null the binding not released
the fallbackvalue is set in this case

I use a static command

public class NullCommand : ICommand
{
    private static readonly Lazy<NullCommand> _instance = new Lazy<NullCommand>(() => new NullCommand());

    private NullCommand()
    {
    }

    public event EventHandler CanExecuteChanged;

    public static ICommand Instance
    {
        get { return _instance.Value; }
    }

    public void Execute(object parameter)
    {
        throw new InvalidOperationException("NullCommand cannot be executed");
    }

    public bool CanExecute(object parameter)
    {
        return false;
    }
}

public class NullCommand : ICommand

{

private static readonly Lazy<NullCommand> _instance = new Lazy<NullCommand>(() => new NullCommand());

private NullCommand()

{

}

public event EventHandler CanExecuteChanged;

public static ICommand Instance

{

get { return _instance.Value; }

}

public void Execute(object parameter)

{

throw new InvalidOperationException("NullCommand cannot be executed");

}

public bool CanExecute(object parameter)

{

return false;

}

and i use like this

<MenuItem Header="sample"
          Command="{Binding Selected.CloseCommand, FallbackValue={x:Static NullCommand.Instance}}"/>

1 2	<MenuItem Header="sample" Command="{Binding Selected.CloseCommand, FallbackValue={x:Static NullCommand.Instance}}"/>

Categories: Non classé Tags:

Alternative for ICollectionView (for sorting update)

09/01/2019 admin Aucun commentaire

When you want to sort a collection in MVVM you use

ICollectionView view = CollectionViewSource.GetDefaultView(Items);
view.SortDescriptions.Clear();
view.SortDescriptions.Add(new SortDescription("DirtyName", ListSortDirection.Descending));

ICollectionView view = CollectionViewSource.GetDefaultView(Items);

view.SortDescriptions.Clear();

view.SortDescriptions.Add(new SortDescription("DirtyName", ListSortDirection.Descending));

but if you want to update sorting in treeview for sample you can use

ListCollectionView view = new ListCollectionView(collection);
view.IsLiveSorting = true;
SortDescription sort = new SortDescription("DirtyName", ListSortDirection.Ascending);
view.SortDescriptions.Add(sort);

ListCollectionView view = new ListCollectionView(collection);

view.IsLiveSorting = true;

SortDescription sort = new SortDescription("DirtyName", ListSortDirection.Ascending);

view.SortDescriptions.Add(sort);

and set IsLiveSorting to true

for sample see converter using in TreeView for update sorting hierarchical

public class TreeViewSortConverter : IValueConverter
{
    public string SortName { get; set; } = null;

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        System.Collections.IList collection = value as System.Collections.IList;
        ListCollectionView view = new ListCollectionView(collection);
        view.IsLiveSorting = true;
        SortDescription sort = new SortDescription(parameter.ToString(), ListSortDirection.Ascending);
        view.SortDescriptions.Add(sort);

        return view;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return null;
    }
}

public class TreeViewSortConverter : IValueConverter

{

public string SortName { get; set; } = null;

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)

{

System.Collections.IList collection = value as System.Collections.IList;

ListCollectionView view = new ListCollectionView(collection);

view.IsLiveSorting = true;

SortDescription sort = new SortDescription(parameter.ToString(), ListSortDirection.Ascending);

view.SortDescriptions.Add(sort);

return view;

}

public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)

{

return null;

}

and using

<TreeViewSortConverter x:Key="tvsc" SortName=""/>
......
<TreeView ItemsSource="{Binding Nodes,
                            Converter={StaticResource tvsc},
                            ConverterParameter=NameDirty}"
.....
<HierarchicalDataTemplate DataType="{x:Type local:Node}"
                          ItemsSource="{Binding Items, 
                                                Converter={StaticResource tvsc},
                                                ConverterParameter=NameDirty}">
.....

......

<TreeView ItemsSource="{Binding Nodes,

Converter={StaticResource tvsc},

ConverterParameter=NameDirty}"

.....

<HierarchicalDataTemplate DataType="{x:Type local:Node}"

ItemsSource="{Binding Items,

Converter={StaticResource tvsc},

ConverterParameter=NameDirty}">

.....

Categories: Non classé Tags: Converter, sort, TreeView, wpf

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Synchronize items Width in WrapPanel

FallbackValue for Command

Alternative for ICollectionView (for sorting update)

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