// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
// 
//
// Description: Adorner for column resize.
// 
 
using System.Windows.Media;
 
namespace System.Windows.Documents.Internal
{
    internal class ColumnResizeAdorner : Adorner
    {
        //------------------------------------------------------
        //
        //  Constructors
        //
        //------------------------------------------------------
 
        #region Constructors
        
        /// <summary>
        /// C'tor for adorner
        /// </summary>
        /// <param name="scope">
        /// FramwerokElement with TextView to which this element is attached
        /// as adorner.
        /// </param>
        internal ColumnResizeAdorner(UIElement scope) : base(scope)
        {
            Debug.Assert(scope != null);
 
            // position
            _pen = new Pen(new SolidColorBrush(Colors.LightSlateGray), 2.0);
 
            _x = Double.NaN;
            _top = Double.NaN;
            _height = Double.NaN;
        }
 
        #endregion Constructors
 
        //------------------------------------------------------
        //
        //  Public Methods
        //
        //------------------------------------------------------
 
        #region Public Methods
 
        /// <summary>
        /// Add a transform so that the adorner is in right spot.
        /// </summary>
        /// <param name="transform">
        /// The transform applied to the object the adorner adorns
        /// </param>
        /// <returns>
        /// Transform to apply to the adorner
        /// </returns>
        public override GeneralTransform GetDesiredTransform(GeneralTransform transform)
        {
            GeneralTransformGroup group;            
            TranslateTransform translation;
 
            group = new GeneralTransformGroup();            
            translation = new TranslateTransform(_x, _top);
 
            group.Children.Add(translation);
 
            if (transform != null)
            {
                group.Children.Add(transform);
            }
 
            return group;
        }
 
        #endregion Public Methods
 
        //------------------------------------------------------
        //
        //  Protected Methods
        //
        //------------------------------------------------------
 
        #region Protected Methods
 
 
        protected override void OnRender(DrawingContext drawingContext)
        {
            // Render as a 2 pixel wide rect, one pixel in each bordering char bounding box.
 
            drawingContext.DrawLine(_pen, new Point(0, 0), 
                                          new Point(0, _height));
        }
 
        #endregion Protected Events
 
        //------------------------------------------------------
        //
        //  Internal Methods
        //
        //------------------------------------------------------
 
        #region Internal Methods
 
        /// <summary>
        /// Updates position for adorner.
        /// </summary>
        /// <param name="newX">
        /// </param>
        internal void Update(double newX)
        {
            if(_x != newX)
            {
                _x = newX;
                AdornerLayer adornerLayer;
 
                adornerLayer = VisualTreeHelper.GetParent(this) as AdornerLayer;
                if (adornerLayer != null)
                {
                    // It may be null when TextBox is detached from a tree
                    adornerLayer.Update(AdornedElement);
                    adornerLayer.InvalidateVisual();
                }
            }
        }
 
        internal void Initialize(UIElement renderScope, double xPos, double yPos, double height)
        {
            Debug.Assert(_adornerLayer == null, "Attempt to overwrite existing AdornerLayer!");
 
            _adornerLayer = AdornerLayer.GetAdornerLayer(renderScope);
 
            _adornerLayer?.Add(this);
 
            _x = xPos;
            _top = yPos;
            _height = height;
        }
 
        internal void Uninitialize()
        {
            _adornerLayer?.Remove(this);
            _adornerLayer = null;
        }
 
        #endregion Internal methods
 
        //------------------------------------------------------
        //
        //  Private Methods
        //
        //------------------------------------------------------
 
        #region Private Methods
 
        #endregion Private methods
 
        //------------------------------------------------------
        //
        //  Private Fields
        //
        //------------------------------------------------------
 
        #region Private Fields
 
        // x position
        private double _x;
 
        // top position
        private double _top;
 
        // height
        private double _height;
 
        private Pen _pen;
 
        // Cached adornerlayer
        private AdornerLayer _adornerLayer;
 
        #endregion Private Fields
    }
}