BUG in WPF? TextBlock inside Adorner display inverse text when FlowDirection is RightToLeft

Question

I'm using adorner to display a watermark inside my textbox. but when i set FlowDirection of window to RightToLeft, text inside adorner (which is textblock) is inverse!!!

Is that a bug or i should change something?

and here is full code of adorner:

namespace Hezareh.Modules.Accounting  
{
    using System.Windows;
    using System.Windows.Controls;
    using System.Windows.Data;
    using System.Windows.Documents;
    using System.Windows.Media;


    internal class WatermarkAdorner : Adorner
    {
        #region Private Fields

        private readonly ContentPresenter contentPresenter;

        #endregion

        #region Constructor

        public WatermarkAdorner(UIElement adornedElement, object watermark) :
            base(adornedElement)
        {
            this.IsHitTestVisible = false;
            this.contentPresenter = new ContentPresenter();
            this.contentPresenter.Content = watermark;
            this.contentPresenter.Opacity = 0.5;
            this.contentPresenter.Margin = new Thickness(Control.Margin.Left + Control.Padding.Left, Control.Margin.Top + Control.Padding.Top, 0, 0);
            if (this.Control is ItemsControl && !(this.Control is ComboBox))
            {
                this.contentPresenter.VerticalAlignment = VerticalAlignment.Center;
                this.contentPresenter.HorizontalAlignment = HorizontalAlignment.Center;
            }

            // Hide the control adorner when the adorned element is hidden
            Binding binding = new Binding("IsVisible");
            binding.Source = adornedElement;
            binding.Converter = new BooleanToVisibilityConverter();
            this.SetBinding(VisibilityProperty, binding);
        }

        #endregion

        #region Protected Properties

        protected override int VisualChildrenCount
        {
            get { return 1; }
        }

        #endregion

        #region Private Properties

        private Control Control
        {
            get { return (Control)this.AdornedElement; }
        }

        #endregion

        #region Protected Overrides

        protected override Visual GetVisualChild(int index)
        {
            return this.contentPresenter;
        }

        protected override Size MeasureOverride(Size constraint)
        {
            // Here's the secret to getting the adorner to cover the whole control
            this.contentPresenter.Measure(Control.RenderSize);
            return Control.RenderSize;
        }

        protected override Size ArrangeOverride(Size finalSize)
        {
            this.contentPresenter.Arrange(new Rect(finalSize));
            return finalSize;
        }

        #endregion
    }

}

and i use it:

        <toolkit:AutoCompleteBox Margin="5" Text="" Name="searchCategoriesTextBox">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="TextChanged">
                    <i:InvokeCommandAction Command="{Binding SearchCommand}"  />
                </i:EventTrigger>
            </i:Interaction.Triggers>
            <local:WatermarkService.Watermark>
                <TextBlock TextAlignment="Left" Text="جستجو" FontFamily="Tahoma" Margin="3, -3, 3, 0" />
            </local:WatermarkService.Watermark>
        </toolkit:AutoCompleteBox>

thanks in advance :)

Answer 1

Well, finally i found another solution to solve this. i used RenderTransofrm to mirror control inside adorner like this:

    <local:WatermarkService.Watermark>
        <TextBlock Name="watermarkTextBox" 
                    Text="{x:Static resources:Resources.SearchCodingTreeView}" 
                    RenderTransformOrigin="0.5,0.5" TextAlignment="Right">
        <TextBlock.RenderTransform>
            <ScaleTransform ScaleX="-1" />
        </TextBlock.RenderTransform>
        </TextBlock>
    </local:WatermarkService.Watermark>

RenderTransformOrigin="0.5,0.5" put pivot in center of control and ScaleX="-1" flip it horizontally.

Answer 2

Actually, this isn't a bug ... it's just implicit...

Source : https://wpf.2000things.com/2013/02/21/761-how-flowdirection-affects-horizontalcontentalignment/

To cancel this implicit behaviour, you need to explicitly set the FlowDirection of each inner element that wouldn't match your requirements ;)

Answer 3

I think I had seen some bug issues with Adorner on the MSDN while I was doing some research on adorner (which I never really used because they didnt suit my needs.).

I cant find the link to where the issues of adorners were discussed, but Im pretty sure its out there.