DataGridColumnFloatingHeader.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Controls / DataGridColumnFloatingHeader.cs / 1305600 / DataGridColumnFloatingHeader.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// Copyright (C) Microsoft Corporation.  All rights reserved.
//
//--------------------------------------------------------------------------- 

using System; 
using System.Windows; 
using System.Windows.Controls.Primitives;
using System.Windows.Media; 

using MS.Internal;

namespace System.Windows.Controls 
{
    ///  
    /// The control which would be used to indicate the drag during column header drag-drop 
    /// 
    [TemplatePart(Name = "PART_VisualBrushCanvas", Type = typeof(Canvas))] 
    internal class DataGridColumnFloatingHeader : Control
    {
        #region Constructors
 
        static DataGridColumnFloatingHeader()
        { 
            DefaultStyleKeyProperty.OverrideMetadata( 
                typeof(DataGridColumnFloatingHeader),
                new FrameworkPropertyMetadata(DataGridColumnHeader.ColumnFloatingHeaderStyleKey)); 

            WidthProperty.OverrideMetadata(
                typeof(DataGridColumnFloatingHeader),
                new FrameworkPropertyMetadata(new PropertyChangedCallback(OnWidthChanged), new CoerceValueCallback(OnCoerceWidth))); 

            HeightProperty.OverrideMetadata( 
                typeof(DataGridColumnFloatingHeader), 
                new FrameworkPropertyMetadata(new PropertyChangedCallback(OnHeightChanged), new CoerceValueCallback(OnCoerceHeight)));
        } 

        #endregion

        #region Static Methods 

        private static void OnWidthChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        { 
            DataGridColumnFloatingHeader header = (DataGridColumnFloatingHeader)d;
            double width = (double)e.NewValue; 
            if (header._visualBrushCanvas != null && !DoubleUtil.IsNaN(width))
            {
                VisualBrush brush = header._visualBrushCanvas.Background as VisualBrush;
                if (brush != null) 
                {
                    Rect viewBox = brush.Viewbox; 
                    brush.Viewbox = new Rect(viewBox.X, viewBox.Y, width - header.GetVisualCanvasMarginX(), viewBox.Height); 
                }
            } 
        }

        private static object OnCoerceWidth(DependencyObject d, object baseValue)
        { 
            double width = (double)baseValue;
            DataGridColumnFloatingHeader header = (DataGridColumnFloatingHeader)d; 
            if (header._referenceHeader != null && DoubleUtil.IsNaN(width)) 
            {
                return header._referenceHeader.ActualWidth + header.GetVisualCanvasMarginX(); 
            }

            return baseValue;
        } 

        private static void OnHeightChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        { 
            DataGridColumnFloatingHeader header = (DataGridColumnFloatingHeader)d;
            double height = (double)e.NewValue; 
            if (header._visualBrushCanvas != null && !DoubleUtil.IsNaN(height))
            {
                VisualBrush brush = header._visualBrushCanvas.Background as VisualBrush;
                if (brush != null) 
                {
                    Rect viewBox = brush.Viewbox; 
                    brush.Viewbox = new Rect(viewBox.X, viewBox.Y, viewBox.Width, height - header.GetVisualCanvasMarginY()); 
                }
            } 
        }

        private static object OnCoerceHeight(DependencyObject d, object baseValue)
        { 
            double height = (double)baseValue;
            DataGridColumnFloatingHeader header = (DataGridColumnFloatingHeader)d; 
            if (header._referenceHeader != null && DoubleUtil.IsNaN(height)) 
            {
                return header._referenceHeader.ActualHeight + header.GetVisualCanvasMarginY(); 
            }

            return baseValue;
        } 

        #endregion 
 
        #region Methods and Properties
 
        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();
            _visualBrushCanvas = GetTemplateChild(VisualBrushCanvasTemplateName) as Canvas; 
            UpdateVisualBrush();
        } 
 
        internal DataGridColumnHeader ReferenceHeader
        { 
            get
            {
                return _referenceHeader;
            } 

            set 
            { 
                _referenceHeader = value;
            } 
        }

        private void UpdateVisualBrush()
        { 
            if (_referenceHeader != null && _visualBrushCanvas != null)
            { 
                VisualBrush visualBrush = new VisualBrush(_referenceHeader); 

                visualBrush.ViewboxUnits = BrushMappingMode.Absolute; 

                double width = Width;
                if (DoubleUtil.IsNaN(width))
                { 
                    width = _referenceHeader.ActualWidth;
                } 
                else 
                {
                    width = width - GetVisualCanvasMarginX(); 
                }

                double height = Height;
                if (DoubleUtil.IsNaN(height)) 
                {
                    height = _referenceHeader.ActualHeight; 
                } 
                else
                { 
                    height = height - GetVisualCanvasMarginY();
                }

                Vector offset = VisualTreeHelper.GetOffset(_referenceHeader); 
                visualBrush.Viewbox = new Rect(offset.X, offset.Y, width, height);
 
                _visualBrushCanvas.Background = visualBrush; 
            }
        } 

        internal void ClearHeader()
        {
            _referenceHeader = null; 
            if (_visualBrushCanvas != null)
            { 
                _visualBrushCanvas.Background = null; 
            }
        } 

        private double GetVisualCanvasMarginX()
        {
            double delta = 0; 
            if (_visualBrushCanvas != null)
            { 
                Thickness margin = _visualBrushCanvas.Margin; 
                delta += margin.Left;
                delta += margin.Right; 
            }

            return delta;
        } 

        private double GetVisualCanvasMarginY() 
        { 
            double delta = 0;
            if (_visualBrushCanvas != null) 
            {
                Thickness margin = _visualBrushCanvas.Margin;
                delta += margin.Top;
                delta += margin.Bottom; 
            }
 
            return delta; 
        }
 
        #endregion

        #region Data
 
        private DataGridColumnHeader _referenceHeader;
        private const string VisualBrushCanvasTemplateName = "PART_VisualBrushCanvas"; 
        private Canvas _visualBrushCanvas; 

        #endregion 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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DataGridColumnFloatingHeader.cs source code in C# .NET

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