Is it possible to give an Adorner an absolute position or to move it for example a bit more to the left?

Question

At the moment I am having the problem that the displayed error goes over several labels or textboxes. I was hoping that I would be able to give the adorner an absolute postion. If that is not possible than I would like to move it to the left. Now I was not able to find useful information on the internet about the positioning of adorners. So I am wondering is there a way to change to position of an adorner?

I am able to paste my code here if it would help to get a solution for the positioning of the adorner.

All help will be appreciated

Thanks in advance

Answer 1

You should derive from the Adorner object, and override location determination logic there, which would allow you to do all kinds of tricks, including absolute / relative positioning.

public class ControlAdorner: Adorner
{
    #region Private fields

    // Utilized for caching of offset by x co-ordinate.
    private double m_OffsetX = 0d;

    // Uri    private double m_OffsetY = 0d;
    #endregion

    #region Initialization
    public ControlAdorner( UIElement adornedElement )
        : base( adornedElement )
        {

        }
    #endregion

    #region Implementation
    //Measures content.
    protected override Size MeasureOverride( Size constraint )
    {
        m_child.Measure( constraint );
        return AdornedElement.RenderSize;
    }

    //Arranges child control to the full size.
    protected override Size ArrangeOverride( Size finalSize )
    {
        m_child.Arrange( new Rect( finalSize ) );
        return m_child.RenderSize;
    }

    public override GeneralTransform GetDesiredTransform( GeneralTransform transform )
    {
        GeneralTransformGroup group = new GeneralTransformGroup();
        group.Children.Add( transform );
        group.Children.Add( new TranslateTransform( OffsetX, OffsetY ) );
        return group;
    }

    //Get visual by index.
    protected override Visual GetVisualChild( int index ) 
    {
        return m_child;
    }

    private static void OnOffsetXChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
    {
        ControlAdorner instance = (ControlAdorner)d;
        instance.OnOffsetXChanged( e );
    }

    private void OnOffsetXChanged( DependencyPropertyChangedEventArgs e )
    {
        m_OffsetX = (double)e.NewValue;
        if( OffsetXChanged != null )
        {
            OffsetXChanged( this, e );
        }
    }

    private static void OnOffsetYChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
    {
        ControlAdorner instance = (ControlAdorner)d;
        instance.OnOffsetYChanged( e );
    }

    private void OnOffsetYChanged( DependencyPropertyChangedEventArgs e )
    {
        m_OffsetY = (double)e.NewValue;
        if( OffsetYChanged \!= null )
        {
            OffsetYChanged( this, e );
        }
    }
    #endregion

    #region Events
    public event PropertyChangedCallback OffsetXChanged;
    public event PropertyChangedCallback OffsetYChanged;
    public double OffsetX
    {
        get
        {
            return m_OffsetX;
        }
        set
        {
            SetValue( OffsetXProperty, value );
        }
    }
    public double OffsetY
    {
        get
        {
            return m_OffsetY;
        }
        set
        {
            SetValue( OffsetYProperty, value );
        }
    }

    // Gets visual children count, always 1.
    protected override int VisualChildrenCount
    {
        get
        {
            return 1;
        }
    }
    #endregion

    #region Dependency properties
    public static readonly DependencyProperty OffsetXProperty = DependencyProperty.Register( 
      "OffsetX", typeof( double ), typeof( ControlAdorner ),
      new FrameworkPropertyMetadata( 0d,    
        FrameworkPropertyMetadataOptions.AffectsArrange | 
        FrameworkPropertyMetadataOptions.AffectsParentArrange, 
        new PropertyChangedCallback( OnOffsetXChanged ) ) );

    public static readonly DependencyProperty OffsetYProperty = DependencyProperty.Register( 
      "OffsetY", typeof( double ), typeof( ControlAdorner ),
      new FrameworkPropertyMetadata( 0d, 
        FrameworkPropertyMetadataOptions.AffectsArrange |
        FrameworkPropertyMetadataOptions.AffectsParentArrange, 
        new PropertyChangedCallback( OnOffsetYChanged ) ) );
    #endregion
}

http://www.artfulbits.com/technologies/winfx/adorners.aspx