[英]Adding controls to form at runtime with user defined XAML
I want to allow my users to define their controls in my program by importing XAML. 我想允许我的用户通过导入XAML在我的程序中定义他们的控件。
As a simple example let say the user wanted to add a grid they could import the XAML below. 举一个简单的例子,假设用户想要添加一个网格,他们可以在下面导入XAML。 How do I get this added to the forum.
我如何将其添加到论坛中。
<Grid
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Grid.Row="3" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="1,2,1,2">
<Grid.RowDefinitions>
<RowDefinition Height="60" />
<RowDefinition Height="60" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="45" />
<ColumnDefinition Width="45" />
<ColumnDefinition Width="45" />
<ColumnDefinition Width="45" />
<ColumnDefinition Width="45" />
</Grid.ColumnDefinitions>
<Button Grid.Row="0" Grid.Column="0" Content="1" FontSize="14" Margin="1,2,1,2" FontWeight="Bold" />
</Grid>
This is a similar answer to ethicallogics answer but I don't like that he references FrameworkElement in his ViewModel. 这是与道德逻辑答案类似的答案,但我不喜欢他在自己的ViewModel中引用FrameworkElement。 This couples your ViewModel to WPF.
这将您的ViewModel耦合到WPF。 Instead, I'd load the content from the user into a string property in your ViewModel.
相反,我会将用户的内容加载到ViewModel中的字符串属性中。
ViewModel 视图模型
public string DynamicXaml
{
get { return _dynamicXaml; }
set
{
if (_dynamicXaml != value)
{
_dynamicXaml = value;
RaisePropertyChanged(() => DynamicXaml);
}
}
}
Then create a converter to convert a string to a FrameworkElement. 然后创建一个转换器,将字符串转换为FrameworkElement。
Converter 转换器
[ValueConversion(typeof(string), typeof(FrameworkElement))]
public class XamlStringConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
FrameworkElement result = null;
string xaml = value as string;
if (!string.IsNullOrEmpty(xaml))
{
try
{
result = XamlReader.Parse(xaml) as FrameworkElement;
}
catch (Exception ex)
{
//add logging logic here.
}
}
return result;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return null;
}
}
And finally you can use a ContentControl or ContentPresenter to display the custom xaml. 最后,您可以使用ContentControl或ContentPresenter来显示自定义xaml。
XAML XAML
<ContentControl x:Name="DynamicControl"
Content="{Binding Path=DynamicXaml, Converter={StaticResource XamlConverter}}"/>
First Lets create an AttachedProperty so that the loaded xaml could be added to any Panel or ContentControl we want. 首先,我们创建一个AttachedProperty,以便可以将加载的xaml添加到我们想要的任何Panel或ContentControl中。
public class MyFrameworkObject : DependencyObject
{
public static readonly DependencyProperty RuntimeFrameWorkElementProperty = DependencyProperty.RegisterAttached("RuntimeFrameWorkElement", typeof(FrameworkElement), typeof(MyFrameworkObject),new PropertyMetadata(new PropertyChangedCallback(OnPropertyChanged)));
static void OnPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
SetRuntimeFrameWorkElement(d as UIElement, e.NewValue as FrameworkElement);
}
public static void SetRuntimeFrameWorkElement(UIElement element, FrameworkElement value)
{
if (element!=null && value != null && value.Parent == null) //The loaded Control can be added to only one Control because its Parent will be set
{
var panel = element as Panel;
if (panel != null)
{
panel.Children.Add(value);
return;
}
var contentControl = element as ContentControl;
if (contentControl != null)
contentControl.Content = value;
//TODO:ItemsControl
}
}
}
ViewModel :In ViewModel lets Create and load a property that could be binded to above attached property.
ViewModel:在ViewModel中,可以创建并加载可以绑定到上述附加属性的属性。
public class ViewModel : INotifyPropertyChanged
{
public ViewModel()
{
LoadXaml();
}
FrameworkElement frameWorkElement;
public FrameworkElement RuntimeFrameWorkElement
{
get { return frameWorkElement; }
set { frameWorkElement = value; OnPropertyChanged("RuntimeFrameWorkElement"); }
}
public void LoadXaml()
{
FileInfo f = new FileInfo(@"F:\myxaml.txt"); //Load xaml from some external file
if (f.Exists)
using (var stream = f.OpenRead())
{
this.RuntimeFrameWorkElement = XamlReader.Load(stream) as FrameworkElement;
}
}
void OnPropertyChanged(string propName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
public event PropertyChangedEventHandler PropertyChanged;
}
xaml.cs
xaml.cs
public MainWindow()
{
InitializeComponent();
DataContext = new ViewModel();
}
xaml lets use the attachedProperty
xaml让我们使用AttachedProperty
<Window x:Class="StackoverflowQues.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:StackoverflowQues"
Title="MainWindow" Height="350" Width="525">
<StackPanel>
<Button Content="Ok"/>
<Grid local:MyFrameworkObject.RuntimeFrameWorkElement="{Binding RuntimeFrameWorkElement}"></Grid>
</StackPanel>
Simillarly you can bind this attachedproperty to any Panel like Stack,Dock,Wrap ,Grid
类似地,您可以将此附加属性绑定到任何面板,如Stack,Dock,Wrap,Grid
<StackPanel local:MyFrameworkObject.RuntimeFrameWorkElement="{Binding RuntimeFrameWorkElement}">
</StackPanel>
Or can also bind to ContentControl or ItemsControl(yet to do)
或者也可以绑定到ContentControl或ItemsControl(尚未完成)
Output i have used same xaml as yours
输出我使用了与您相同的xaml
Note: If you specify this attached property to two or more panels or controls it will be added to the first one only . 注意:如果您将此附加属性指定给两个或多个面板或控件,则它将仅添加到第一个。 Because then the Parent of the Loaded xaml control will be set and wont be able to add another control.
因为那样,将设置“已加载xaml”控件的“父级”,因此将无法添加另一个控件。
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