Develop Reference

Reordering ListBox elements with gong-wpf-dragdrop causes visual bugs

Task
My task was to be able to change the order of the service cards in the ListBox by dragging and dropping. I found a good solution on StackOverflow that has a lot of useful features (gong-wpf-drag drop, https://stackoverflow.com/a/33367826/19631476).
Problem
However, I had to face an unpleasant visual bug: when I drag the service card, there is some label that indicates where the dragged object will be moved. So, for some reason, this label is clipped if a number of objects are also clipped and not visible in the ListBox. However, when scrolling, the cropping does not disappear. Moreover, then the label will always point to the line above, wherever it is.
Problem demo
below I will present some screenshots demonstrating the problem
the normal state of the separator
the separator is cut off due to the fact that the card does not fit into the container
the separator continues to be cut off after scrolling
the separator is shifted up a line, and is still clipped, despite the fact that I move the elements already in another line
My code
This is how my ListBox element looks like:
<ListBox
Margin="10 0 10 10"
Background="Cornsilk"
MinWidth="300"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
dd:DragDrop.IsDragSource="True"
dd:DragDrop.IsDropTarget="True"
dd:DragDrop.SelectDroppedItems="True"
ItemsSource="{Binding ServicesListCollectionView.View}"
SelectedIndex="{Binding SelectedServiceIndex}"
SelectedItem="{Binding SelectedService}"
d:ItemsSource="{d:SampleData ItemCount=5}">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<Border AllowDrop="True" Style="{StaticResource BorderStyle}">
<DockPanel Background="GhostWhite">
<!-- Service Card Template-->
</DockPanel>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
it contains a custom container so that the service cards can be arranged as a grid from top to bottom
What have I tried to do?
The idea came to my mind to prohibit the use of ScrollBar for the ListBox element. It worked, and the visual bug sort of disappeared. But you can't leave it like that. I wrapped the ListBox in ScrollViewer and allowed it to scroll vertically. This visual bug is no longer there:
code:
<ScrollViewer VerticalScrollBarVisibility="Auto" x:Name="ServiceScroll">
<!-- Here is ListBox -->
</ScrollViewer>
However, this solution is not suitable:
I lose control of scrolling in the ListBox and can only use scrolling on the ScrollViewer itself
Scrolling also becomes unavailable when dragging items.
the second problem can be solved by specifying the dd:DragDrop.DropTargetScrollViewer ScrollViewer with binding to the ScrollViewer element:
<ScrollViewer VerticalScrollBarVisibility="Auto" x:Name="ServiceScroll">
<ListBox
...
dd:DragDrop.IsDragSource="True"
dd:DragDrop.IsDropTarget="True"
dd:DragDrop.SelectDroppedItems="True"
dd:DragDrop.DropTargetScrollViewer="{Binding ElementName=ServiceScroll}"
...
></ListBox>
</ScrollViewer>
but in this case, the visual bug described above appears again, and also, this solution still does not allow you to scroll through the elements inside the ListBox using the mouse wheel.
Any ideas?
To be honest, I do not know what to do. Has anyone encountered anything described above?
Maybe I'm doing something wrong, which is why I get such strange behavior? What's wrong with scrolling?
Maybe you have good solutions to solve the problem? How else would it be possible to solve the issue of dragging items to the ListBox in the most flexible way?

Adding a custom font to a windows phone 8 app

I've read articles such as this 31 days of windows phone day 24 embedding-fonts and this windows 8 xaml tips custom fonts that explain very clearly and simply how to do this.
But for some reason I can't figure out, my custom font doesn't show on my app, whether in the designer view or when I run it.
To be sure I haven't left any step out, I'm showing what I did here for any suggestions on what my issue might be:
1. First, this is my xaml textblock code
<StackPanel Grid.Row="1" x:Name="BottomPanel" Height="120" Width="800" Orientation="Horizontal">
<StackPanel.Background>
<SolidColorBrush Color="{StaticResource PhoneSemitransparentColor}"/>
</StackPanel.Background>
<TextBlock x:Name="MainTextBlock" FontFamily="/Fonts/KOMIKAX_.ttf" TextWrapping="Wrap" Text="Hello" Width="680" Height="120" Margin="10,0,0,0" FontSize="25" Padding="20,10"/>
</StackPanel>
2. I created a folder in my project, called it "Fonts" and that is where I copied my font file.
3. I changed the Build Action of the font file to Content. I left the Copy To Output Directory property as None at first, then changed it to Copy If Newer. No success.
What have I done wrong or what did I leave out?

This work for me.
First make a folder in your App with the name Fonts, then Add font to it, then use the following syntax. I used it, it works perfectly.
<TextBlock FontFamily="/Fonts/Comic.ttf#Comic" TextWrapping="Wrap" Text="Hello" FontSize="25"/>
Make sure that the Build Action must be set to Content,
Right Click on font in folder and click property, then select Build Action as Content, otherwise it will not work on Emulator and Device.

Try using this
<TextBlock x:Name="MainTextBlock" FontFamily=".\Fonts\KOMIKAX_.ttf#Komika Axis" TextWrapping="Wrap" Text="Hello" Width="680" Height="120" Margin="10,0,0,0" FontSize="25" Padding="20,10"/>
In case this doesn't work, remember the format is .\FontPath\FontFileName.ttf#FontName

Building comment tree efficiently in Metro XAML

I am trying to build a 'comments control' (In a win8 XAML app, which is similar to Silverlight) which will load and render a comment tree for the user.
Each comment can have 0 or 1+ children comments (which recurses through each comment).
Each comment displays a set of info, including author, time, the comment itself, etc.
The approach I initially took to build this is to use a ListView which has a 'CommentItem' control binding.
<TextBlock Grid.Row="1" TextWrapping="Wrap" Text="{Binding commentText}" FontSize="11" FontFamily="Global User Interface" />
<ListView Grid.Row="2" x:Name="CommentRepliesList" ItemsSource="{Binding}" >
<ListView.ItemTemplate>
<DataTemplate>
<local:CommentItem Tag="{Binding}"></local:CommentItem>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
The above will just recurse through each comment, apply the comment text, and then create a new commentitem for each comment child, recurse through again, etc.
The issue, however, is this is extremely slow and non-performant.
Does anyone know a more efficient way to do this? Is ListView the appropriate control to use for this?

ComboBox Dropdown Appears Beneath Window

So I was have a combobox like below, coded like this;
AllowsTransparency="True" Background="Transparent">
<Border CornerRadius="10" Background="Beige" BorderBrush="Aqua" BorderThickness="2">
<Grid>
<StackPanel VerticalAlignment="Center" HorizontalAlignment="Center">
<Label Name="lblText"></Label>
<ComboBox Name="cbxNumbers"></ComboBox>
<TextBox Name="txtNumbers" Visibility="Collapsed"></TextBox>
<Button HorizontalAlignment="Center" Name="btnDone"
Click="btnDone_Click">That's Right!</Button>
</StackPanel>
<Button VerticalAlignment="Bottom" HorizontalAlignment="Right" Margin="1"
FontSize="8" Name="btnChangeInput" Click="btnChangeInput_Click">Let me chose the number
</Button>
</Grid>
</Border>
And then populated in code like this;
lblText.Content = Text;
cbxNumbers.Items.Add(5);
cbxNumbers.Items.Add(10);
cbxNumbers.Items.Add(50);
cbxNumbers.Items.Add(100);
cbxNumbers.Items.Add(1000);
cbxNumbers.Items.Add(10000);
cbxNumbers.Items.Add(100000);
cbxNumbers.Items.Add(1000000);
cbxNumbers.SelectedIndex = 0;
My question is obviously, why is my Dropdown showing beneath my window?
UPDATE
Quote Microsoft
Thank you for reporting this issue. Though this issue is under
investigation, we will likely not have a fix available in .NET 4.0. We
will update this bug again when we are able to fix the issue in a
future release. Thanks!
Great... any ideas for a work around?

This is a well documented bug with AllowTransparency=TRUE. It only happens on some computers running Win XP.
http://connect.microsoft.com/VisualStudio/feedback/details/465964/wpf-combobox-dropdown-list-appears-behind-the-form-when-allowstransparency-true
A workaround is found here:
As noted before, this is an issue with layered windows on XP. There is
not much that can be done at the WPF level to solve this, and given
that XP is no longer being serviced this isn't very likely to be
fixed. There are potentially workarounds you can employ, though.
The source of the problem is that WPF uses something called "Layered
Windows" when WindowStyle=None and AllowsTransparency=True. Often the
reason for doing this is to implement custom window chrome. Recently
the WPF team published a library that allows you to get custom chrome
without resorting to layered windows. The library is available at
http://code.msdn.microsoft.com/WPFShell
This doesn't support per-pixel opacity, but it does allow for
completely custom rendering of the window, including areas normally
managed by the system. It lets you set the radii of the windows
corners, but not have a completely arbitrary shape. If you can use
this library instead of AllowsTransparency=True then it should solve
this issue.
Microsoft has issued a hotfix, but it seems to not have fixed all problems related to the issue.

Silverlight: Layout changes when I call NavigationService.Navigate

This is a really weird bug. I have no idea why it could be happening. I know that posting it here is a bit of a long-shot, but I'm out of other ideas.
I have two ListBoxs that act as menus.
<ListBox Margin="56,8,15,0" FontSize="64"
ItemsSource="{Binding FavoriteSections}"
SelectionChanged="MenuList_SelectionChanged">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<toolkit:ContextMenuService.ContextMenu>
<toolkit:ContextMenu>
<toolkit:MenuItem Header="Remove" Click="FavoritesContextMenuItem_Click" />
</toolkit:ContextMenu>
</toolkit:ContextMenuService.ContextMenu>
<TextBlock Text="{Binding DisplayName}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<ListBox x:Name="sectionList" Margin="56,8,15,0" FontSize="64"
SelectionChanged="MenuList_SelectionChanged"
ItemsSource="{Binding SectionViewModels}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<toolkit:ContextMenuService.ContextMenu>
<toolkit:ContextMenu>
<toolkit:MenuItem Header="Add to favorites" Click="SectionContextMenuItem_Click" />
</toolkit:ContextMenu>
</toolkit:ContextMenuService.ContextMenu>
<TextBlock Text="{Binding DisplayName}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The bug exists across both of them.
When the selection changes on either menu, this method is called:
void MenuList_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (e.AddedItems.Count == 0)
{
return;
}
Uri page = null;
object selected = e.AddedItems[0];
if (selected is NavigableItem)
{
NavigableItem selectedItem = (NavigableItem)selected;
page = selectedItem.Page;
}
else if (selected is SectionViewModel)
{
SectionViewModel selectedVM = (SectionViewModel)selected;
page = selectedVM.Section.Page;
}
Debug.Assert(page != null, "What is the type of `selected`?");
// if I comment out this line, the problem goes away:
NavigationService.Navigate(page);
ListBox selectedBox = (ListBox)sender;
selectedBox.SelectedIndex = -1;
}
If I comment out the NavigationService.Navigate() line, the problem goes away. If I replace the line with a different URI, the problem remains.
About 70% of the time, when I click on a menu item, the content jumps all over the page. (The remaining 30%, no bug occurs.) It happens too quickly to see what's really going on, but different UI elements overlap each other.
This only occurs the first time I click on something in those menus during the app's lifetime. If I hit "back" then select a menu item again, the problem will not occur.
What could be happening here? I really have no idea. The code-behind doesn't have a OnNavigatedFrom method, so I don't think it's a problem there.
I'm using Silverlight for Windows Phone 7
Update: Mysteriously, I can't seem to reproduce this in the debugger - only after deploying the app and running it in the emulator unattached. ???
Update 2: The bug appears when NavigationService.Navigate() is called from the Click event handler of a button, as well:
<Button Content="Foo" Click="Button_Click" Grid.Row="0"/>
private void Button_Click(object sender, RoutedEventArgs e)
{
NavigationService.Navigate(new Uri("/Views/sections.xaml?section=43", UriKind.Relative));
}
Looks like the bug has to do with the navigation, not the UI element used to trigger the call.
Update 3: More weirdness. Still not able to reproduce the app while the debugger is attached. If I make the loading progress bar always collapsed, the bug disappears:
<ProgressBar x:Name="LoadingProgressBar"
IsIndeterminate="True"
Visibility="Collapsed"
Style="{StaticResource PerformanceProgressBar}"
VerticalAlignment="Top"/>
Alternatively, commenting out this line in code-behind makes the bug disappear:
LoadingProgressBar.Visibility = Visibility.Collapsed;
I really don't understand what's going on here. That line of code is not executed when the page is navigated from.
Here is the full XAML of the control that's getting messed up:
<ProgressBar x:Name="LoadingProgressBar"
IsIndeterminate="True"
Visibility="Collapsed"
Style="{StaticResource PerformanceProgressBar}"
VerticalAlignment="Top"/>
<TextBlock x:Name="DownloadFailed"
Visibility="Collapsed"
Style="{StaticResource disabledText}"
Margin="56,8,8,-8" >
FooBar.com could not be reached. Do you have a network connection?
</TextBlock>
<ListBox x:Name="sectionList" Margin="56,8,15,0" FontSize="64"
SelectionChanged="MenuList_SelectionChanged"
ItemsSource="{Binding SectionViewModels}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<toolkit:ContextMenuService.ContextMenu>
<toolkit:ContextMenu>
<toolkit:MenuItem Header="Add to favorites" Click="SectionContextMenuItem_Click" />
</toolkit:ContextMenu>
</toolkit:ContextMenuService.ContextMenu>
<TextBlock Text="{Binding DisplayName}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</controls:PivotItem>

The problem lies in your usage of the Indeterminate ProgressBar. All its animations are done on the UI thread, and not the Compositor thread, as is the usual practise. Since you are already using the Windows Phone Toolkit, you can easily replace your ProgressBar with the PerformanceProgressBar offered by the toolkit. This should solve your problems.

Before I begin, let me say that I don't have a lot of experience with Windows Phone, so my answers are based on more generic WPF knowledge, so forgive me if I'm overlooking specifics of the platform, or am referencing features not available.
Some diagnostic questions (sorry this isn't a direct answer):
Firstly, it does seem like Navigate is calling a lot of layoutUpdates. I haven't yet seen what type of container is containing the pages you're updating, but it is worth asking, is that also being disrupted or only the menus?
Secondly, could you try specifying your itemPanel explicitly? You're expecting them to be virtualizingStackPanels, but you may find that some parent object in your visual hierarchy is creating a different inheritance scenario.
You have these in a grid, which is meant to size to its content, or take the default size (100x100 in normal WPF) or take sizing from its parent, which without knowing how you've specified the grid, or the grid's parent, it's difficult to know its behaviour. Furthermore, Grids automatically z-order their children according to the order in which they were added. Can you determine whether it is just the layout of the lisboxes that is being disturbed, or whether it is the entire grid? Or, is it larger than that?
If you attach to the layoutUpdated() event of the listboxes, grid, or grid's parent, you should be able to look at the stacktraces that lead you there - it sounds to me that you'll find that layoutUpdated() is firing more than you'd like it to. Further, you'll be able to output the heights and widths (ActualHeight etcetera of course) during those steps so that you can see when exactly those changes happen.
I hope that some of these diagnostic steps might help you reach an answer.