Question

I have a TextBlock control in my view, its Width depends on the Text property.

I’m looking for some way to bind the TextBlocks Width to a property in my model,which will work as follows:

1. The setting of the Width must be done automatically based on Text
2. In my button click I would like to retrieve the Width

I’ve tried the code below, but it keeps the Width as 0 if I don’t explicitly set it in the constructor of the view model.Tried Mode=OneWayToSource and Mode=OneWay but it made no difference, any suggestions?

View:

<Grid>
    <TextBlock Text="Some text" Width="{Binding TextWidth,Mode=OneWayToSource}" />
    <Button Content="Show Width" Height="30" Width="90" Command="{Binding ShowTextWidth}" />
</Grid>

View model:

public event PropertyChangedEventHandler PropertyChanged;

public void OnPropertyChanged(string propertyName)
{
    if (PropertyChanged != null)
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}

private DelegateCommand<object> showTextWidth;
public DelegateCommand<object> ShowTextWidth
{
    get { return showTextWidth; }
    set { showTextWidth = value; }
}

private double textWidth;
public double TextWidth
{
    get { return textWidth; }
    set 
    { 
        textWidth = value;
        OnPropertyChanged("TextWidth");
    }
}

public ViewModel()
{
    //If I explicitly specify the width it works:
    //TextWidth = 100;
    ShowTextWidth = new DelegateCommand<object>(ShowWidth);
}

private void ShowWidth(object parameter)
{
    MessageBox.Show(TextWidth.ToString());
}

}

Answer 1

Ended up creating an attached behavior by Maleak which was inspired by Kent Boogaarts Pushing read-only GUI properties back into ViewModel, can’t believe it’s so complicated to push the value of ActualWidth into the view model!