Bind an ObservableCollection to Lines

问题

I want to have a graphical part in my UserControl which will display Lines based on a collection (and update coords during runtime and also add/remove lines during runtime based on the collection).

Lets assume I have a class called Class1:

public class Class1 : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged(PropertyChangedEventArgs e)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, e);
        }

        private int _x1 = 0;
        public int X1
        {
            get { return _x1; }
            set
            {
                _x1 = value;
                OnPropertyChanged(new PropertyChangedEventArgs("X1"));
            }
        }
    }

And an ObservableCollection in my UserControl:

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged(PropertyChangedEventArgs e)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, e);
        }

        private ObservableCollection<Class1> _classes = new ObservableCollection<Class1>();
        public ObservableCollection<Class1> Classes
        {
            get { return _classes; }
        }

If I knew the amount of Lines I could create the number of lines in my UserControl like this:

XAML:

<Grid DataContext="{Binding ElementName=LayoutRoot}">
<Line X1="{Binding Items[0].X1}" X2="100" Y1="50" Y2="100" Stroke="Red" StrokeThickness="4"/>
<Line X1="{Binding Items[1].X1}" ... />
...
</Grid>

How should I proceed please?

Thanks for any efforts

回答1:

You could use an ItemsControl and create a DataTemplate for the Class1 object and bind your ObservableCollection to the ItemsControl.

It may also be a good idea to use Canvas as the ItemsPanelTemplate if you want to draw lines all over the place

Here is a quick example:

Xaml:

<Grid DataContext="{Binding ElementName=UI}">
    <ItemsControl ItemsSource="{Binding Classes}">
        <ItemsControl.ItemsPanel>
            <ItemsPanelTemplate>
                <Canvas />
            </ItemsPanelTemplate>
        </ItemsControl.ItemsPanel>
        <ItemsControl.ItemTemplate>
            <DataTemplate DataType="{x:Type local:Class1}">
                <Line Stroke="Black" StrokeThickness="2" Fill="Black" X1="{Binding X1}" X2="{Binding X2}" Y1="{Binding Y1}" Y2="{Binding Y2}" />
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
</Grid>

Code:

public partial class MainWindow : Window
{

    public MainWindow() 
    {
        InitializeComponent();
        Random ran = new Random();
        for (int i = 0; i < 10; i++)
        {
            Classes.Add(new Class1 { X1 = ran.Next(0,100), Y1 = ran.Next(0,100), X2 = ran.Next(0,100), Y2 = ran.Next(0,100) }); 
        }
    }

    private ObservableCollection<Class1> _classes = new ObservableCollection<Class1>();
    public ObservableCollection<Class1> Classes
    {
        get { return _classes; }
    }

}

Result:

回答2:

You could use an ItemsControl as Container to display your lines.

<ItemsControl DataContext="{Binding ElementName=LayoutRoot}" 
              ItemsSource={Binding}>
  <ItemsControl.ItemTemplate>
    <DataTemplate>
      <Line X1="{Binding Items[0].X1}" X2="100" Y1="50" Y2="100" Stroke="Red" StrokeThickness="4"/>
    </DataTemplate>
  </ItemsControl.ItemTemplate>
</ItemsControl>

来源：https://stackoverflow.com/questions/15426460/bind-an-observablecollection-to-lines

标签

wpf

data-binding

user-controls