DataGrid研究笔记-1

下面是我研究DataGrid的一点心得：

首先wpf datagrid binding，网上的列子多不胜数，这里就没必要再列举了，下面主要说的是datagrid的焦点控制。

默认的datagrid焦点控制都是由Tab控制的，按一下tab，焦点移动到下一个.但是其他的控件的焦点控制是用回车控制的，不是很统一。接下来我所要做的就是用回车键来控制datagrid的焦点移动。

先来说说我网上搜到的方法：

public class ExDataGrid:DataGrid
    {
        protected override void OnPreviewKeyDown(System.Windows.Input.KeyEventArgs e)
        {
            base.OnPreviewKeyDown(e);
        }
    }

override了OnPreviewKeyDown方法，使用基本控件的base.OnPreviewKeyDown，即回车控制焦点，但是有些问题，碰到表格里是datatemplate或者是combobox的时候，移动会有些问题。

网上也没有搜到其他方法，没办法只能求助于reflector看看微软是怎么实现tab焦点控制的。

UIElement focuseElement = Keyboard.FocusedElement as UIElement;
FocusNavigationDirection focusNavigationDirection = flag2 ?
                        FocusNavigationDirection.Previous : FocusNavigationDirection.Next;
                    TraversalRequest request = new TraversalRequest(focusNavigationDirection);
                    request.Wrapped = true;
focuseElement.MoveFocus(request)

不过可恶的是，除了wpf提供OnKeyDown可以override之外，其他方法都是private的，没办法只能照着他的思路，自己写一套了。

private void OnEnterKeyDown(System.Windows.Input.KeyEventArgs e)
        {
            _isMouseClick = false;
            DataGridCell currentCellContainer = null;
            if (this.CurrentCell.Column.Header!=null)
            {
                currentCellContainer = this.TryFindCell(this.CurrentCell);               
            }
            else
            {
                currentCellContainer = this.CurrentCellContainer;
            }
            
            if (currentCellContainer != null)
            {
                bool isEditing = currentCellContainer.IsEditing = true;
                bool flag2 = (e.KeyboardDevice.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift;
                UIElement focuseElement = Keyboard.FocusedElement as UIElement;
                var myDataGridTextColumn = currentCellContainer.Column as MyDataGridTextColumn;
                
                ContentElement element2 = (focuseElement == null) ? (Keyboard.FocusedElement as ContentElement) : null;
                if (focuseElement != null || element2 != null)
                {
                    e.Handled = true;
                    FocusNavigationDirection focusNavigationDirection = flag2 ?
                        FocusNavigationDirection.Previous : FocusNavigationDirection.Next;
                    TraversalRequest request = new TraversalRequest(focusNavigationDirection);
                    request.Wrapped = false;
                    if (focuseElement != null && focuseElement.MoveFocus(request) || element2 != null && element2.MoveFocus(request))
                    {
                        _preUIElement = focuseElement;
                        this.BringIntoView();
                        if (isEditing && flag2 && Keyboard.FocusedElement == currentCellContainer)
                            currentCellContainer.MoveFocus(request);
                        if (base.IsGrouping && isEditing)
                        {
                            DataGridCell cellForSelectAndEditOnFocusMove = this.GetCellForSelectAndEditOnFocusMove();
                            if (cellForSelectAndEditOnFocusMove != null && GetRowDataItem(cellForSelectAndEditOnFocusMove) == GetRowDataItem(currentCellContainer))
                            {
                                DataGridCell cell3=this.TryFindCell(GetRowDataItem(cellForSelectAndEditOnFocusMove),cellForSelectAndEditOnFocusMove.Column);
                                if (cell3 == null)
                                {
                                    base.UpdateLayout();
                                    cell3 = this.TryFindCell(GetRowDataItem(cellForSelectAndEditOnFocusMove), cellForSelectAndEditOnFocusMove.Column);
                                }
                                if (cell3 != null && cell3 != cellForSelectAndEditOnFocusMove)
                                    cell3.Focus();
                            }
                        }
                        
                        this.SelectAndEditOnFocusMove(e, currentCellContainer, isEditing, false, true,focuseElement);
                    }
                }
            }
        }

然后就可以override OnKeyDown

protected override void OnKeyDown(System.Windows.Input.KeyEventArgs e)
        {
            if (this.Items.IndexOf(this.CurrentItem) == this.Items.Count - 1
                && this.Columns.IndexOf(this.CurrentColumn) == this.Columns.Count - 1)
            {
                return;
            }
            if (e.Key == Key.Enter)
                OnEnterKeyDown(e);
            //base.OnKeyDown(e);
        }

这样基本的功能就完成了。