I have the following XAML code:
<ListBox x:Name="ListBox1"
ItemsSource="{Binding UserBase}"
SelectedItem="{Binding User}"
SelectionMode="Single"
AllowDrop="True"
myOwnDragDrop:DragDropSource="{Binding}"
myOwnDragDrop:DragDropTarget="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}" AllowDrop="True" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<ListBox x:Name="ListBox2"
ItemsSource="{Binding UserBase}"
SelectedItem="{Binding User}"
SelectionMode="Single"
myOwnDragDrop:Source="{Binding}"
myOwnDragDrop:Target="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}" AllowDrop="True" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
So this actually works in my MVVM implementation (at least the dragging and dropping part). The problem is that in the interface of both of the dependent properties only gives me:
public void Drop(object data)
Where data is actually the entire view object in which ListBox1 resides. In theory there is no problem, but I was wondering how do I get the correct user that was dropped upon without making any changes to the interface or dependent property implementation?
Note the dependent property seems to be handling the event private static void Drop(object sender, DragEventArgs e), but I can't access the e.
In case this is totally impossible, is it possible to retrieve the user that was dropped upon from the DragEventArgs?
Thank you for everything!
First of all: Have you looked at GongSolutions WPF DragDrop library?
It's free, and available on NuGet, and makes implementing drag/drop in WPF a lot easier, but with still retaining complete control over the process.
In particular, the Drop() method exposes an IDropInfo object, which gives you access to all sorts of information about the drag/drop process (including the source and target UIElements).
I spent quite a bit of time trying to implement drag and drop from scratch a while ago, but found this library far easier to implement, and it allowed me to add all my drag/drop functionality to my ViewModel rather than my codebehind.
There's some good get-you-started documentation on the GitHub pages.
Secondly, with regards to how do you obtain the user the drag was dropped onto (without using the above library):
When I implemented drag/drop between listboxes, I found I needed to enable and handle AllowDrop on each ListItem. You might want to try creating a custom ItemPanelTemplate for your listbox, and enabling AllowDrop on the panel. That way, the 'object data' you will receive should the the ListItemPanel, from which you can access the DataContext to obtain the User.
Related
Okay, to start, I'm pretty inexperienced with WPF and XAML, so any pointers or advice would be greatly appreciated.
I have a scheduling program that I'm working on that I need some help setting up. I had things working previously, but it wasn't organized correctly. I had UI elements in my ViewModels that I would add to a StackPanel at the initialization of the MainWindow. Generally not MVVM style coding. So I made some views (UserControls) to display the things I have, and most everything broke.
Basically, I have a Schedule ViewModel that has some parameters and a list of a different Room ViewModels. Each Room ViewModel has a RoomSchedule ViewModel that contains a list of RoomEvent ViewModels.
I'm trying to write controls for the things that need displaying. I've created a Schedule view, which has a list box of Room views, and the Room view uses the RoomEvent view to display the events of the room. The Room view uses the WPF Extended Toolkit's TimelinePanel, the rest of the controls are pretty much basic controls. The general idea has been: a model provides data to the ViewModel, which massages that data to what needs to be displayed. So an Event should know how to display itself, a Room should know how to display itself, and the Schedule should know how to display itself.
The problem I'm running into is: now that I've scooted everything from the xaml.cs or ViewModel files to their appropriate places, the controls aren't rendering at all. I've been reading other SO postings where people have the same problem, but none of them seem to work for beginner stuff like this. I think I'm close, it seems like all the controls are being created, and the DataContext's are being set correctly, but nothing is showing up.
This is, basically, what I have so far. I left some of the xaml boilerplate stuff off for succinctness:
Schedule.xaml:
<StackPanel>
<ListBox ItemsSource="{Binding Rooms}" >
<ListBox.ItemTemplate>
<DataTemplate>
<localcontrols:RoomView ScheduleStart="{Binding ElementName=ScheduleControl, Path=DataContext.Start}"
</DataTemplate>
<ListBox.ItemTemplate>
</ListBox>
</StackPanel>
RoomView.xaml:
<extended:TimelinePanel BeginDate="{Binding localcontrols:ScheduleStart}" EndDate="{Binding localcontrols:ScheduleEnd}"
<ItemsControl ItemsSource="{Binding Path=mRoomSchedule.mScheduledEvents}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<localcontrols:EventView />
</DataTemplate>
</ItemsControls.ItemTemplate>
</ItemsControl>
</extended:TimelinePanel>
EventView.xaml:
<Border BorderThickness="1" BorderBrush="Black" extended:TimelinePanel.Date="{Binding mStartTime}" extended:TimelinePanel.DateEnd="{Binding mEndTime}">
<TextBlock Background="{Binding mColor}" Text="{Binding mEventID}" />
</Border>
The ScheduleStart and ScheduleEnd are dependency properties defined in RoomView.xaml.cs. My thinking was that Schedule would have Start and End properties that would be set in its constructor, and the RoomViews in the ListBox would bind to those properties to set the TimelinePanel's BeginDate and EndDate.
Maybe your bindings are wrong. When I need to bind to a dependency property I use the ElementName feature of binding to say which control I want and I give the root node a name, in this case Root. It's one way to solve it.
<UserControl
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:local="clr-namespace:Weingartner.Controls"
x:Class="RoomView"
x:Name="Root">
<extended:TimelinePanel
BeginDate="{Binding ElementName=Root, Path=ScheduleStart}"
EndDate="{Binding ElementName=Root, Path=ScheduleEnd}"
>
<ItemsControl ItemsSource="{Binding Path=mRoomSchedule.mScheduledEvents}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<localcontrols:EventView />
</DataTemplate>
</ItemsControls.ItemTemplate>
</ItemsControl>
</extended:TimelinePanel>
</UserControl>
I have a TreeView that I am binding to an ItemsSource that creates a CheckBox for each item. Here is the xaml:
<TreeView x:Name="ReasonTreeView" Height="Auto" Background="Transparent"
BorderThickness="0" IsTabStop="False"
ItemsSource="{Binding Path=AnswerOptions}">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate DataType="{x:Type QSB:Answer}" ItemsSource="{Binding Path=AnswerOptions}">
<StackPanel Orientation="Horizontal">
<CheckBox Margin="0,5"
IsChecked="{Binding Path=IsSelected}"
IsEnabled="{Binding Path=Value,
Converter={StaticResource ReasonValueToEnabledConverter}}"
Visibility="{Binding Path=AnswerOptions,
Converter={StaticResource ParentNodeVisConverter}}" />
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
In my application I then create multiple instances of these. Depending on the instance of the TreeView, certain CheckBoxes need to be disabled so the user can not select them, however I'm uncertain of how I can access the individual items in the HierarchicalDataTemplate in the code.
After looking around for a while the only thing I can think of is to build the whole TreeView in the code behind instead of the xaml, but I would rather not have to resort to that. Is there anything else that I can do?
To help clarify my point and for illustrative purposes, this is essentially what I want to be able to do (in pseudocode): ReasonTreeView.ItemsSource[5].IsEnabled = false;
Which would disable the CheckBox (and any other controls in that HierarchicalDataTemplateItem) at index 5 of the TreeView's ItemsSource
Let me know if more information is needed
I meant that binding on the checkbox's isenabled property Path=Value. That Value member has to be bool and implement INotifyPropertyChanged then you can control IsEnabled from your model. Dont forget to add Mode=Twoway to your binding
Instead of accessing the CheckBox through Control.ItemsSource property you should make the change in your underlying collection (that is itemssource of your control). After making the change notify the View (your Control) that data has been changed so update the control.
Implement INotifyPropertyChanged in your underlying class and after changing the Property (which is responsible for Enabled/Disabled) value Notify the View.
If you are not familiar with concepts of Data Binding and INotifyPropertyChanged, I would suggest you to read some basic tutorials about it. It is one of the major feature of WPF which makes life very easy for doing things like yours
I am building an app for Windows Phone, and in this app I have a list of Movies with Title, Plot and Picture.
I have this list bound to a ListBox with a custom DataTemplate for the items showing the data. I also created a second page to show the details of each movie.
My problem now is the navigation between these pages. I'm using MVVM to build the applications and most of the approaches I've found searching on internet is to use the OnSelectionChanged event in the code-behind, but it goes agains what I want, that is to use MVVM.
Other approach I've seen, which is the one I'm trying, is to bind the SelectedItem to a property in the ViewModel, but I can't make it change the property, it seems that I cannot select an item in the listbox. Also, I don't have the visual feedback when I press one of the items in my listbox, like the feedback we have in the settings menu of the phone for example.
The code I'm using in the listbox is:
<ListBox Margin="0,0,-12,0" ItemsSource="{Binding Movies}" SelectedItem="{Binding SelectedMovieItem}" SelectionMode="Single" >
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Margin="0,0,0,17">
<!--Replace rectangle with image-->
<Rectangle Height="50" Width="50" Fill="#FFE5001b" Margin="12,0,9,0"/>
<StackPanel Width="311">
<TextBlock Text="{Binding Name}" TextWrapping="NoWrap" Style="{StaticResource PhoneTextExtraLargeStyle}" Foreground="#000" />
<!--<TextBlock Text="{Binding LineTwo}" TextWrapping="Wrap" Margin="12,-6,12,0" Style="{StaticResource PhoneTextSubtleStyle}"/>-->
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Another approach I've seen is to use the INavigationService to achieve this, I found this article: http://windowsphonegeek.com/articles/MVVM-in-real-life-Windows-Phone-applications-Part1
I read the parts one and two, but I couldn't understand this one works.
So, what I want to know is whether the approach I'm using is the correct to make a page navigation, or if there is a better way using MVVM to do this with visual feedback on the listbox.
Why is handling Event in the code behind against MVVM? Handling events interaction is part of the UI. Of course you won't all you code logic there. But you are trying just to go to the next page. I do something like this :
private void MainListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
// If selected index is -1 (no selection) do nothing
if (MainListBox.SelectedIndex == -1)
return;
// Navigate to the new page
NavigationService.Navigate(new Uri("/Views/detailsPage.xaml?selectedItem=" + MainListBox.SelectedIndex, UriKind.Relative));
// Reset selected index to -1 (no selection)
MainListBox.SelectedIndex = -1;
}
I'm quite new to C# and Windows Phone 7 for that sake, but none the less, I've thrown myself into trying to make a small app for myself. Here's my problem:
I'm trying to set up a DataTemplate that will position my Name and Drinks variables that I've declared in MainPage.xaml.cs. Here's my action when button1 is clicked:
private void button1_Click(object sender, RoutedEventArgs e)
{
string Name = participantName.Text;
int Drinks = 0;
listBox1.Items.Add(Name + Drinks);
}
And here is my DataTemplate from MainPage.xaml
<ListBox Height="Auto" HorizontalAlignment="Stretch" Margin="7,74,0,0" Name="listBox1" VerticalAlignment="Stretch" Width="Auto">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Height="132">
<TextBlock Text="{Binding Path=Name}" FontSize="35" />
<StackPanel Width="370">
<TextBlock Text="{Binding Path=Drinks}" FontSize="35" />
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The problem is that my data is not shown. It works perfectly without the DataTemplate, but as soon as I use it, my text simply doesn't get through. Your help is very much appreciated.
The template itself is ok. The bindings on the template, though, are currently incorrect.
When you add a new item to the list box, you are just adding a plain old string (which is currently missing a space, BTW.) Your bindings, though, expect the object in the list to have a Name property and a Drinks property, which of course the string class does not have.
The usual solution here is to logically separate your data model from your presentation, by creating a class to store the data itself (probably PersonDrink, with the appropriate Name and Drinks properties) and then adding those objects to the list.
You should read up on the MVVM pattern, as it provides an excellent way to ensure that changes in your data are reflected in your view, and visa versa.
http://amarchandra.wordpress.com/2011/12/18/binding-multiple-object-in-wp7-using-listbox/
Here is a sample for binding data using a datatemplate. I hope this might help you.
I'm having a problem with the autocompletebox from the toolkit for windows phone. I bind it to some data, then when i press it and start typing, it discovers some items but they are displayed wrong (the list is shown separated from the box, and also if i click on any item, nothing happens. If i click where the item would be supposed to be (for example, right on the top of the box), then it gets selected. It looks like a rendering problem (bug?)) but perhaps i'm doing something wrong. Here's the code for the box :
<DataTemplate x:Key="DataTemplate1">
<ContentControl Content="{Binding Name}" Margin="8,7"/>
</DataTemplate>
<toolkit:AutoCompleteBox ItemsSource="{Binding}" x:Name="txtSelectValues" MinWidth="250" Margin="0,0,0,0" ItemTemplate="{StaticResource DataTemplate1}" VerticalAlignment="Top" />
Found it. It's a bug with the AutoCompleteBox. When inside a scrollviewer control, the dropdown gets messed up and displayed in an incorrect position
Its not just that is also to do with being placed inside of a Pivot/Panaroma as well as the scrollviewer, the silverlight gurus have stated they haven't a timeline for the fix for the Pivot control, and there is a nasty hack
http://silverlight.codeplex.com/workitem/7574
I think the answer might just be that you shouldn't be using a ContentControl directly used like this. Try using something like a TextBlock instead - e.g.:
<DataTemplate x:Key="DataTemplate1">
<TextBlock Text="{Binding Name}" Margin="8,7"/>
</DataTemplate>
If that's not the answer, then try pulling back to a simple example - especially removing all the Margin's, Width's, Alignment's, etc - then put them back in one-by-one to work out and understand what is causing the effect you are seeing.