ListViewItem in WrapPanel occupying space when collapsed - wpf

I have a ListView using a WrapPanel as its ItemsPanel, and I use ListViewItem directly as content. But when one ListViewItem.Visibility is Collapsed, you can still see the space it's using.
First off, a sample XAML code similar to what I use :
<Grid>
<ListView ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Hidden" ItemContainerStyle="{DynamicResource ContainerStyle}">
<ListView.Resources>
<Style TargetType="{x:Type ListViewItem}" x:Key="ContainerStyle">
<Setter Property="Background" Value="Transparent" />
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListViewItem}">
<ContentPresenter />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ListView.Resources>
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel ItemHeight="200" ItemWidth="200"/>
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListViewItem Margin="10" Visibility="Visible">
<Border Background="Red"/>
</ListViewItem>
<ListViewItem Margin="10" Visibility="Visible">
<Border Background="Blue"/>
</ListViewItem>
<ListViewItem Margin="10" Visibility="Visible">
<Border Background="Green"/>
</ListViewItem>
</ListView>
</Grid>
For example, when all items are visible (code above) I have this :
But if I change the first item to make it collapsed as follows
<ListViewItem Margin="10" Visibility="Collapsed">
<Border Background="Red"/>
</ListViewItem>
The result is like this :
What I would expect would be the following :
As such I don't understand why it is acting like this, the Collapsedseems to behave just like Hidden. I'm applying it directly to the item and don't see what else to do .
I've tried different solutions I found, most notably this one about binding to Visibility in the style and this one going more or less in the same direction but without success, same results.

The accepted answer actually does not provide a solution, which is instead delivered in its comment section.
If you set ItemWidth, WrapPanel will reserve the ItemWidth for all the items bound to itself, visible or not.
The workaround here is not to set ItemWidth on the WrapPanel but set the Width on the ItemTemplate.
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel MinWidth="96" />
</DataTemaplate>
</ItemsControl.ItemTemplate>

I think that the issue you see is related to the fact that even collapsed, a ListViewItem is still an Item, and the WrapPanel will detect 3 items, not 2.

A good working solution seems to be overriding the "Arrange" methods of Panel, in a custom Panel.
I'm working on the base of this great class AlignableWrapPanel (inheriting from Panel, not WrapPanel), and I got it working by replacing this :
var child = children[i];
if (child == null) continue;
with this :
var child = children[i];
if (child == null) continue;
if (child.Visibility == Visibility.Collapsed) continue;
The methods are ArrangeOverride, ArrangeLine, and MeasureOverride. ArrangeLineis a bit different, but the line with if(child == null) continue;is pretty easy to spot ; just add the one with Collapsed after that.
That solution should work with any

Related

Grouping, virtualization and scrolling in a ListBox

Using following code ListBox jumps to the next group during scrolling. Since one group shows more items than can fit screen, user never sees all items of the group.
Since I have a lot of items I need viritualization.
Setting CanContentScroll="False" fixes the issue but then virtualization is gone and UI hangs for 20 seconds. Is there a way around this?
<ListBox
VirtualizingStackPanel.IsVirtualizing="True"
VirtualizingStackPanel.VirtualizationMode="Recycling"
ScrollViewer.CanContentScroll="True">
<ListBox.GroupStyle>
<GroupStyle HidesIfEmpty="True">
<GroupStyle.ContainerStyle>
<Style TargetType="{x:Type GroupItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<Expander IsExpanded="True">
<Expander.Header>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Type}" />
...
</StackPanel>
</Expander.Header>
<ItemsPresenter />
Try using the ScrollUnit=Pixel property to get smooth scrolling. The default is ScrollUnit=Item which causes the group to scroll as one unit.
<ListBox
VirtualizingPanel.IsVirtualizing='True'
VirtualizingPanel.IsVirtualizingWhenGrouping='True'
VirtualizingPanel.ScrollUnit='Pixel'
/>

Zero-height of ScrollViewer-templated item inside ItemsControl?

I have an ItemsControl with arbitrary items. Some of the items are wrapped inside a ScrollViewer. The code-behind for these scrollable items makes use of the ViewportWidth (almost equivalent to ActualWidth) and ViewportHeight (almost equivalent to ActualHeight) properties to arrange/size its visual children. This works as long as I don't put the item inside an ItemsControl. When the item appears in an ItemsControl the value of ViewportHeight equals 0 - effectively making my item invisible. Note that I want to arrange the items vertically, giving all items equal height! No fancy stuff, just a regular StackPanel.
The templates are applied automatically using DataType:
<MyControl.Resources>
<DataTemplate DataType="{x:Type MyScrollableItem}">
<MyControlWrappedInScrollViewer Text="{Binding Text}" />
</DataTemplate>
<DataTemplate DataType="{x:Type MyItem}">
<TextBlock Text="{Binding Text}"/>
</DataTemplate>
</MyControl.Resources>
<ItemsControl ItemsSource="{Binding MyCollection}" />
The structure of MyControlWrappedInScrollViewer looks something like this:
<UserControl>
<Grid>
<ScrollViewer CanContentScroll="True">
<Canvas />
</ScrollViewer>
</Grid>
</UserControl>
Why does my ScrollViewer get the height of 0? How can I tell my ItemsControl to size the item appropriately? E.g. One item yields a height of the ItemsControl height. Two items yield half of it, and so on.
This did the trick:
<Style TargetType="{x:Type ItemsControl}">
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<UniformGrid Columns="1" IsItemsHost="True"/>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Style>

WPF ListView/Gridview allow users to select multiple items and group them together

I have a WPF ListView/GridViwe in a MVVM application. GridView is bound to a List in the ViewModel.
The requirement is that the users should be able to select multiple rows of the gridview, right-click on it and see a context menu "Group These Together". Once selected, all these items should be collapsed into one group with a expander or + sign added at the beginning.
Can somebody please help me in getting this working?
I was working on similar problem, but I had to group items by their let's say name. What I've done was create DataTrigger or MultiDataTrigger depending on your data requirements and then when conditions are true i.e. item selected change the container for GroupItem. What I mean is when you create your list view, you have to create it with grouped view, which btw is not grouped as you can declare it without expander and just use the StackPanel. After that you need 3 lines of Code to set the grouping. Here is an example for you:
MAIN.xaml
<ListView
ScrollViewer.CanContentScroll="False"
x:Name="lsvProducts"
ItemsSource="{Binding Products, NotifyOnSourceUpdated=True}"
MouseDown="lsvProducts_MouseDown">
<ListView.View>
<GridView>
<GridViewColumn Width="Auto" Header="Code" DisplayMemberBinding="{Binding ID}"/>
<GridViewColumn Width="Auto" Header="Description" DisplayMemberBinding="{Binding Desc}"></GridViewColumn>
<GridViewColumn Width="Auto" Header="Qty" DisplayMemberBinding="{Binding Qty}"></GridViewColumn>
</GridView>
</ListView.View>
<ListView.GroupStyle>
<GroupStyle ContainerStyle="{StaticResource GroupedView}"/>
</ListView.GroupStyle>
</ListView>
As you can see I have declared an empty container for the grouped style, reson why is because you can't assign it without previous declaration. After this declaration you need this in your generic.xaml
<Style x:Key="GroupedView" TargetType="{x:Type GroupItem}">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=chbx, Path=IsChecked}" Value="True">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<Expander IsExpanded="False">
<Expander.Header>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Name}" FontWeight="Bold" Foreground="Gray" FontSize="22" VerticalAlignment="Bottom" />
<TextBlock Text="{Binding ItemCount}" FontSize="16" Foreground="DimGray" FontWeight="Bold" FontStyle="Italic" Margin="10,0,0,0" VerticalAlignment="Bottom" />
<TextBlock Text=" item(s)" FontSize="16" Foreground="Silver" FontStyle="Italic" VerticalAlignment="Bottom" />
</StackPanel>
</Expander.Header>
<ItemsPresenter />
</Expander>
</ControlTemplate>
</Setter.Value>
</Setter>
</DataTrigger>
After you declared your style for the true value you need to declare one for without expander
<!--This goes in the same style as the prevoius sample code -->
<DataTrigger Binding="{Binding ElementName=chbx, Path=IsChecked}" Value="False">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<StackPanel>
<ItemsPresenter />
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</DataTrigger>
Next step is to define the grouping:
//lsvProducts is our ListView
view = (CollectionView) CollectionViewSource.GetDefaultView(lsvProducts.ItemsSource);
//in the creation parameter you should put field that you want to group by :-)
PropertyGroupDescription grouping = new PropertyGroupDescription("FieldToGroupBy");
view.GroupDescriptions.Add(grouping);
Which should apper in your ViewModel.
Good luck!
Let us know if you need any more help, I'll try my best with my English ;-)
EDIT
I forgot to mention when you assign the grouping you need to check the number of groups already in the collection and only apply it when there is non or 0, otherwise you'll apply the grouping multiple times and the expander will be repeeated in the result window as many times as you added the grouping :-)
What in my mind to select multiple row Ctrl+click
It will select multiple row and on right click open a context menu after setting its Isopen to true
You should also bind selected item to list and Use this item to make an expander

Designing a custom edit control similar to hotmail style "To" box

I am desiging a custom control for use in my application which simulates a hotmail style "To" textbox which lets the user enter semicolon delimited strings. The control behaves like a textbox, on each ener press or entering semicolon a box(a textblock infact) gets created containing text entered which can be manipulated individually.
The control is implemented by means of a listview with its ItemPresenter set to a WrapPanel
The XAML looks like below:
<ListView x:Name="col" ItemContainerStyle="{StaticResource ContainerStyle}">
<ListView.GroupStyle>
<GroupStyle>
<GroupStyle.Panel>
<ItemsPanelTemplate>
<local:MyWrapPanel Orientation="Horizontal" MinWidth="400"/>
</ItemsPanelTemplate>
</GroupStyle.Panel>
</GroupStyle>
</ListView.GroupStyle>
</ListView>
<Style TargetType="{x:Type ListViewItem}" x:Key="ContainerStyle">
<Setter Property="ContentTemplate" Value="{StaticResource BoxView}" />
<Style.Triggers>
<Trigger Property="Tag" Value="Edit">
<Setter Property="ContentTemplate" Value="{StaticResource BoxViewEdit}" />
</Trigger>
</Style.Triggers>
</Style>
The control template for the listviewitems (boxes) looks like:
<DataTemplate x:Key="BoxView">
<Border BorderThickness="1" BorderBrush="Brown" Background="Beige" Margin="1,1,1,0" CornerRadius="6" >
<StackPanel Orientation="Horizontal">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
</Grid.RowDefinitions>
<TextBlock Grid.Column="0" Grid.Row="0" Margin="5,5,5,0" Height="20" Text="{Binding XPath=''}"/>
<DockPanel Grid.Column="1" Grid.Row="0">
<Image Source="edit8.png" MouseLeftButtonUp="edit_MouseLeftButtonUp" ToolTip="Edit" Margin=" 10,0,0,0"></Image>
<Image Source="cancel8.png" MouseLeftButtonUp ="cancel_MouseLeftButtonUp" ToolTip="Remove" Margin=" 5,0,5,0"></Image>
</DockPanel>
</Grid>
</StackPanel>
</Border>
</DataTemplate>
Actually the listview is data bound to a set of xmlnodes having common parent.
The look and feel of the control has to be given such that it looks like a text box.
Now, I have the listview items bound to the xml nodes of an xml document, to show the textbox I add an empty xmlnode in the document and change the control template of the coressponding listviewitem so that it shows as a textbox.
On pressing enter in the text box a new xml node gets appended to the underlying xml at second last position containing innertext set to the textbox text(last positon is dummy node)
The template used for textbox is:
<DataTemplate x:Key="BoxViewEdit">
<TextBox Margin="0,5,5,0" Background="White" MaxWidth="400" BorderThickness="1" Text="{Binding XPath=''}"/>
</DataTemplate>
But the idea of adding an empty dummy xmlnode in the underlying source xml so that i could simulate editing of the listview seems hacky. Is there any cleaner way of doing this.
What i want is to wrap the text box as shown in figure with the contents of the wrappanel seamlessly without adding it to the wrappanel itself by means of creating a dummy xmlnode.
I had the same issue and found some solutions; you can check out the responses and comments here.

Wrap or adorn wpf listview datatemplate

I'm attempting to essentially wrap the contents of a DataTemplate in a ListView GridViewColumn with a border. What I want to know is if it's possible to supply an adorner that will surround that template so that I don't have to specify the border in every single DataTemplate on every column (which is what I'm doing now). I've got something like this, but I know it's not right:
<Style TargetType="{x:Type ListBoxItem}">
<Setter Property="TemplateContent">
<Setter.Value>
<ControlTemplate>
<StackPanel>
<Border BorderBrush="Green" BorderThickness="1">
<AdornedElementPlaceholder />
</Border>
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
This complains that the TemplateContent is not a valid type. I've also tried with DataTemplate and that doesn't work either (understandably so).
I know I could just create a DataTemplate, however the content for each column is different. At the very least, it binds to different fields. I'm wondering if there's a solution using a dynamic resource, but I don't know much about it. Thanks for your help
EDIT: here's a sample of my ListView:
<ListView ItemsSource="{Binding Path=OrderLines}"
ItemContainerStyle="{StaticResource ResourceKey=ListViewItemContainerStyle}">
<ListView.View>
<GridView>
<GridViewColumn>
<GridViewColumn.CellTemplate>
<DataTemplate>
<TextBox MaxWidth="30" Width="30" MaxLength="2"
Text="{Binding Path=Quantity,ValidatesOnDataErrors=True}" />
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
<GridView>
<ListView.View>
</ListView>
Essentially I want to wrap that text box in the DataTemplate and any other items in additional columns.
The property needs to be "Template". See here for an example: http://msdn.microsoft.com/en-us/library/ms750821.aspx

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