ExtendedDataGrid.cs

Toto je zdrojový kód souboru ExtendedDataGrid.cs

Fixing Silverlight and WPF DataGrid control.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;

namespace IMP.Windows.Controls
{
    /// <summary>
    /// Fixed DataGrid control
    /// </summary>
    /// <remarks>
    /// Fixes <c>MouseLeftButtonDown</c> event
    /// Fixes rows selecting with <c>Extended</c> <c>SelectionMode</c> for multiselect DragDrop
    /// Přidává metody <c>HitTest</c>
    /// </remarks>
    public class ExtendedDataGrid : System.Windows.Controls.DataGrid
    {
        #region delegate and events
        /// <summary>
        /// MouseLeftButtonDown event
        /// </summary>
        public new event MouseButtonEventHandler MouseLeftButtonDown;
        #endregion

        #region member varible and default property initialization
        private IList LastSelectionRemovedItems;
        private bool KeyboardStateOnMouseLeftButtonDown;
#if !SILVERLIGHT
        private DataGridRow LeftButtonDowmLastRow;
#endif
        #endregion

        #region constructors and destructors
        /// <summary>
        /// ExtendedDataGrid control constructor
        /// </summary>
        public ExtendedDataGrid()
        {
            base.AddHandler(FrameworkElement.MouseLeftButtonDownEvent, new MouseButtonEventHandler(Base_MouseLeftButtonDown), true);
        }
        #endregion

        #region action methods
        /// <summary>
        /// Get DataGrid Row from mouse position in <c>MouseEventArgs</c>
        /// </summary>
        /// <param name="e"><c>MouseEventArgs</c></param>
        /// <returns>DataGrid Row</returns>
        public DataGridRow HitTest(MouseEventArgs e)
        {
#if SILVERLIGHT
            var root = Application.Current.RootVisual;
            return HitTest(e.GetPosition(root));
#else
            return HitTest(e.GetPosition(this));
#endif
        }

#if SILVERLIGHT
        /// <summary>
        /// Get DataGrid Row from mouse position in <c>DragEventArgs</c>
        /// </summary>
        /// <param name="e"><c>DragEventArgs</c></param>
        /// <returns>DataGrid Row</returns>
        public DataGridRow HitTest(Microsoft.Windows.DragEventArgs e)
        {
            var root = Application.Current.RootVisual;
            return HitTest(e.GetPosition(root));
        }
#else
        /// <summary>
        /// Get DataGrid Row from mouse position in <c>DragEventArgs</c>
        /// </summary>
        /// <param name="e"><c>DragEventArgs</c></param>
        /// <returns>DataGrid Row</returns>
        public DataGridRow HitTest(DragEventArgs e)
        {
            return HitTest(e.GetPosition(this));
        }
#endif

        /// <summary>
        /// Get DataGrid Row from mouse position relative to RootVisual
        /// </summary>
        /// <param name="pt"><c>Point</c> with mouse position relative to RootVisual</param>
        /// <returns>DataGrid Row</returns>
        public DataGridRow HitTest(Point pt)
        {
#if SILVERLIGHT
            var root = Application.Current.RootVisual;
            var elements = VisualTreeHelper.FindElementsInHostCoordinates(pt, root);

            foreach (var element in elements)
            {
                var row = element as DataGridRow;
                if (row != null)
                {
                    //Kontrola zda Row patří k gridu this
                    if (this.Columns[0].GetCellContent(row) != null)
                    {
                        return row;
                    }
                }
            }
#else
            var hitResultsList = new List<UIElement>();
            VisualTreeHelper.HitTest(this, null, result =>
            {
                var element = result.VisualHit as UIElement;
                if (element != null)
                {
                    hitResultsList.Add(element);
                }
                return HitTestResultBehavior.Continue;
            }, new PointHitTestParameters(pt));

            var elements = hitResultsList;

            foreach (var element in elements)
            {
                var row = GetVisualParent<DataGridRow>(element);
                if (row != null)
                {
                    //Kontrola zda Row patří k gridu this
                    if (this.Columns[0].GetCellContent(row) != null)
                    {
                        return row;
                    }
                }
            }
#endif

            return null;
        }
        #endregion

        #region private member functions
        /// <summary>
        /// Overrides OnSelectionChanged
        /// </summary>
        protected override void OnSelectionChanged(System.Windows.Controls.SelectionChangedEventArgs e)
        {
            this.LastSelectionRemovedItems = null;
            if (this.SelectionMode == DataGridSelectionMode.Extended && e.RemovedItems.Count != 0 && e.AddedItems.Count == 0 &&
                (Keyboard.Modifiers & ModifierKeys.Control) == 0 && (Keyboard.Modifiers & ModifierKeys.Shift) == 0)
            {
                //Označení záznamu, který již byl označen jako součást multiselektu
                //Zapamatování pro obnovu označení na MouseLeftButtonDown
                this.LastSelectionRemovedItems = e.RemovedItems;
            }

            base.OnSelectionChanged(e);
        }

        private void Base_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            this.OnMouseLeftButtonDown(e);
        }

        /// <summary>
        /// Raise MouseLeftButtonDown event
        /// </summary>
        protected new virtual void OnMouseLeftButtonDown(MouseButtonEventArgs e)
        {
#if !SILVERLIGHT
            this.LeftButtonDowmLastRow = null;
#endif

            if (this.LastSelectionRemovedItems != null)
            {
                if (this.ItemsSource != null)
                {
#if !SILVERLIGHT
                    this.LeftButtonDowmLastRow = this.HitTest(e);
#endif

                    //Vrácení označení podle zapamatování v OnSelectionChanged
                    foreach (var item in this.LastSelectionRemovedItems)
                    {
                        try
                        {
                            this.SelectedItems.Add(item);
                        }
                        catch (ArgumentException)
                        {
                            //The item is not contained in the ItemsSource.
                        }
                    }
                }

                this.LastSelectionRemovedItems = null;
            }

            this.KeyboardStateOnMouseLeftButtonDown = (Keyboard.Modifiers & ModifierKeys.Control) != 0 || (Keyboard.Modifiers & ModifierKeys.Shift) != 0;

            if (MouseLeftButtonDown != null)
            {
                MouseLeftButtonDown(this, e);
            }
        }

        /// <summary>
        /// Overrides OnMouseLeftButtonUp
        /// </summary>
        protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
        {
#if SILVERLIGHT
            if (!e.Handled && this.SelectionMode == DataGridSelectionMode.Extended && this.SelectedItems.Count > 1 &&
                (Keyboard.Modifiers & ModifierKeys.Control) == 0 && (Keyboard.Modifiers & ModifierKeys.Shift) == 0 && !this.KeyboardStateOnMouseLeftButtonDown &&
                !Microsoft.Windows.DragDrop.IsDragInProgress)
            {
                var row = this.HitTest(e);
                if (row != null)
                {
                    var item = row.DataContext;
                    this.SelectedItems.Clear();
                    this.SelectedItem = item;
                }
            }
#else
            if (!e.Handled && this.SelectionMode == DataGridSelectionMode.Extended && this.SelectedItems.Count > 1 &&
                (Keyboard.Modifiers & ModifierKeys.Control) == 0 && (Keyboard.Modifiers & ModifierKeys.Shift) == 0 && !this.KeyboardStateOnMouseLeftButtonDown)
            {
                var row = this.HitTest(e);
                if (row != null && row == this.LeftButtonDowmLastRow)
                {
                    var item = row.DataContext;
                    this.SelectedItems.Clear();
                    this.SelectedItem = item;
                }
                this.LeftButtonDowmLastRow = null;
            }
#endif

            this.KeyboardStateOnMouseLeftButtonDown = false;

            base.OnMouseLeftButtonUp(e);
        }

#if !SILVERLIGHT
        private static T GetVisualParent<T>(Visual element) where T : Visual
        {
            T item = default(T);
            var v = VisualTreeHelper.GetParent(element) as Visual;

            while (v != null)
            {
                item = v as T;
                if (item != null)
                {
                    return item;
                }

                v = VisualTreeHelper.GetParent(v) as Visual;
            }

            return null;
        }
#endif
        #endregion
    }
}