Develop Reference

Loading a grid in xaml code from a file, then making it active in main code

I am making a video game, where each grid serves as game room. Each grid\room has a large number of objects like things that can be used, images and sound files. Until now, they all were stored in one large file. But now, I was told that this approach wastes a lot of resources.
My plan is, to store xaml code of every such grid as a separate file, then load relevant file at run time with usual code.
For now xaml looks about like this:
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d" x:Name="wdwMain" x:Class="RealityIncognita.MainWindow"
Height="900" Width="1600" ResizeMode="NoResize" WindowState="Maximized"
Cursor="Cross" WindowStyle="None" Loaded="wdwMain_Loaded">
<Viewbox Stretch="Fill">
<Grid x:Name="areaContainer" HorizontalAlignment="Left" Height="900"
VerticalAlignment="Top" Width="1600">
<Grid x:Name="areaMain">
<Grid.Background>
<ImageBrush
ImageSource="Resources/Images/Interface/main_interface.jpg"/>
</Grid.Background>
<Grid x:Name="areaShowers" HorizontalAlignment="Left" Height="700"
Margin="1653,790,-1561,-590" VerticalAlignment="Top" Width="1508"
IsVisibleChanged="areaShowers_IsVisibleChanged">
Here's example - areaShowers is a grid for relevant room. Until now, it was stored in the main file, like all other grids, and when I needed, I just altered its Margin to put it upon "areaMain" - also a grid.
Now though, I want to put each room into a file, then load it when I need it, and remove it from memory when I don't.
For example I'll create an empty grid "areaGeneric" and add it and it alone to original xaml.
So, I want something like this. Can't provide any earlier attempt, because I don't really know how it can be done.
Grid new_grid = new Grid;
new_grid = load from file (areaRoom.xaml); (file is among the project's
resources)
areaGeneric = new_grid;
Can I load a grid xaml at run-time, then switch grids in main code?
Thank you,
Evgenie

A really simple solution would just be to house each of your rooms inside a user control and then place the control into your container grid when you need to change rooms. Here's the rough idea:
public partial class MainWindow : Window
{
UserControl _currentRoom;
public MainWindow()
{
InitializeComponent();
}
protected override void OnPreviewMouseDown(MouseButtonEventArgs e)
{
this.areaContainer.Children.Clear();
_currentRoom = null;
if (e.LeftButton == MouseButtonState.Pressed)
_currentRoom = new Room1();
if(e.RightButton == MouseButtonState.Pressed)
_currentRoom = new Room2();
this.areaContainer.Children.Add(_currentRoom);
base.OnPreviewMouseDown(e);
}
}
A "Room":
<UserControl x:Class="Test.Room1"
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">
<Button Height="100" Width="100">
Hello world!
</Button>
</UserControl>
As for cleaning up your resources - once the user control is removed from the visual tree (assuming you aren't holding a reference) the GC should dispose of the user control. If you wanted to clear your resources more quickly you could implement a dispose method on your rooms and then call that before you change areas.

WPF user control inheritance issues

I made a WPF control in a library project and would like to extend it with a new one.
<UserControl x:Class="Genesyslab.Desktop.Modules.ExtensionUtils85.GUI.EmbeddingUserControl"
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>
</Grid>
</UserControl>
I have tried to extend it like this:
<src:EmbeddingUserControl x:Class="Interaxalab.Desktop.Modules.PrototipoCable.CustomViews.InteractionView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:src="Genesyslab.Desktop.Modules.ExtensionUtils85.GUI"
Name="InteractionWorksheetView" Height="321.613" Width="471.396"
>
<Grid>
<WindowsFormsHost x:Name="windowsFormsHost1" HorizontalAlignment="Left" Height="284" VerticalAlignment="Top" Width="471"/>
</Grid>
</src:EmbeddingUserControl>
However, I get an error message saying that the name "EmbeddingUserControl" does not exist in namespace "Genesyslab.Desktop.Modules.ExtensionUtils85.GUI".
The name clearly does exist, since the xaml.cs can find it, but for some reason the xaml cannot.
Any help would be appreciated.

Long story short - you cannot inherit control with xaml by another control with xaml (and does it makes sense even to do so?). In your case, EmbeddingUserControl does not contain any visual tree elements (just empty grid), so you can just do:
public class EmbeddingUserControl : UserControl {
// some methods, properties of your control
}
Then you can inherit exactly like you do already in your question (don't forget to inherit from EmbeddingUserControl both in xaml file and in code-behind file).
You can also inherit from user control with xaml, if your inherited control does not have xaml itself (so you can add\override logic).
If you need to inherit some visual stuctures - you have to switch from inheritance to composition. That is: your base control provides some placeholders where other controls may be placed, or even better allows to provide templates to format data items (like for example ItemsControl and ItemTemplate property). Then you just fill those placeholders with other controls if necessary.

Setting frames datacontext

My WPF window should be able to load in different controls in same spot on the window; which should be frames to fulfill that task.
Hence i'm trying to make a frame load different pages by editing a databound string containing the Frames source. And I have managed to do that, however at the moment I have no idea how to share the frames data to the windows viewmodel hosting the frame.
I'm using MVVM and I thougth that if I could also databind a "viewmodel" to the frames datacontext, I could then both choose which page to load and which datacontext the page should use, all from the host window, therefore having access to it.
Below is my xaml.
<Window x:Class="View.Window"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window" Height="300" Width="300">
<Grid>
<Frame NavigationUIVisibility="Hidden" DataContext="{Binding WindowClass.DataContext}" Source="{Binding WindowClass.FrameURI}"/>
</Grid>
However, if I now assign the pages datacontext through this binding, instead of in the code behind, nothing gets loaded. Now I basically end up with a blank frame.
Why?

You can use Window.Resources to bind to your DataContext, then Bind to the FrameURI (You'll need to fix the appropriate namespace instead of my custom xmlns:WindowClass):
<Window x:Class="View.Window"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:WindowClass="clr-namespace:WindowClass"
Title="Window" Height="300" Width="300">
<Window.Resources>
<WindowClass:MyViewModelName/>
</Window.Resources>
<Grid>
<Frame NavigationUIVisibility="Hidden" DataContext={Binding} Source="{Binding FrameURI}"/>
</Grid>
You can find a very basic tutorial here

Access a UserControl from code in WPF app

I have a created a usercontrol in my wpf application. I have used it like so:
<Page x:Class="InstallerToolkit.Pages.PageVideosNvr"
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:my="clr-namespace:MyProject.UserControls"
mc:Ignorable="d"
d:DesignHeight="525" d:DesignWidth="1050"
Title="PageVideos">
<Grid>
<my:UserControlVideoPlayer Name="VideoPlayer" Margin="559,74,35,155">
</my:UserControlVideoPlayer>
</Grid>
Now in my C# page I want to access it but the VideoPlayer object doesnt appear when I type its name in the code behind c# page.
What doo I do to access it as I want to set one of its properties.

Give x:Name to your UserControl instead of Name
<my:UserControlVideoPlayer x:Name="VideoPlayer" Margin="559,74,35,155">
It will be accessible now in code behind using this.VideoPlayer.
I would suggest to make it a thumb rule that always use x:Name whenever referring to elements in XAML.
Refer to this for difference between Name and x:Name.

Adding x:Name to a user control gives error in generated code of page its used in

I am basically using a user control for the first time, so hopefully it's just a dumb mistake.
I have a simple user control
<UserControl x:Class="TestProject.WebApp.myUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:riaControls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.DomainServices"
xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk">
<Grid>
<sdk:AutoCompleteBox Name="myACB" ItemsSource="{Binding Data}" FilterMode="StartsWith" MinimumPrefixLength="2" >
</sdk:AutoCompleteBox>
</Grid>
</UserControl>
I am using the control in another page (in a stack panel):
<navigation:Page x:Class="TestProject.WebApp.myPageView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:local="clr-namespace:TestProject.WebApp"
xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation">
<Grid>
<StackPanel Orientation="Horizontal">
<local:myUserControl x:Name="myUC" />
</StackPanel>
</Grid>
</navigation:Page>
The control is in the same namespace as page. Removing the x:Name allows the project to compile and the control functionally works. When x:Name is specified I get an error in the generated code of the page:
Type 'TestProject.WebApp.myUserControl' is not defined.
It happens on these lines of code:
internal TestProject.WebApp.myUserControl myUC;
this.myUC == (TestProject.WebApp.myUserControl)this.FindName("myUC")
I tried with two different controls. Same thing. The generated code has "using TestProject.WebApp;" so I don't know why there is an error only when I have a named instance of the control.
I also cannot seem to use just the Name property. I even tried overloading the NameProperty in the control.

I was able to find a post about this here:
.g.vb file claims that Type X is not defined, even though it is!
Apparently, there is an issue when a project has a service reference (in my case I am using RIA services) and the user control resides in an assembly with the same root namespace as the one you are trying to use it in.
So for me it was,
TestProject.WebApp
Then I tried creating a new project for just the control
TestProject.Controls
Same problem.
Then, when I renamed the project and changed the namespace to
CustomControls
it worked.
Hopefully this saves someone else from some frustration and I really hope this problem can be fixed by MS soon.

What you are showing here should work. What is the default namespace in your project property's? Also did you rename your user control after you created it. Both of those issues could be causing you problems.