概述
在上面一篇 Windows Community Toolkit 4.0 - DataGrid - Part02 中，我们针对 DataGrid 控件的 Utilities 部分做了详细分享。而在本篇，我们会对控件中最重要的 DataGrid 文件夹中的类做详细的分享。
下面是 Windows Community Toolkit Sample App 的示例截图和 code/doc 地址：
Windows Community Toolkit Doc - DataGrid
Windows Community Toolkit Source Code - DataGrid
Namespace: Microsoft.Toolkit.Uwp.UI.Controls; Nuget: Microsoft.Toolkit.Uwp.UI.Controls.DataGrid;
开发过程
DataGrid 文件夹中是 DataGrid 控件最重要的功能，首先我们还是先来看一下类结构：
包括了 Automation；DataGrid，DataGridColumn，DataGridRow，DataGridCell 控件实现，事件处理参数类和数据类等；
接着我们看几个重要的类和方法：
1. DataGrid.cs
这个类是 DataGrid 控件的主要处理类，功能也是比较复杂，单个类的代码行数是 9001 行，我们只挑两个方法来看一下。其他方法大家有兴趣或用到时可以在 DataGrid.cs 中查阅。
1) DataGrid()
首先看一下 DataGrid 类的构造方法，之所以看这个方法，是想让大家可以更了解 DataGrid 类中变量的初始化方式，这些变量在不同的交互场景下会被赋予不同的值。
public DataGrid()
{
this.TabNavigation = KeyboardNavigationMode.Once;
_loadedRows = new List<DataGridRow>();
_lostFocusActions = new Queue<Action>();
_selectedItems = new DataGridSelectedItemsCollection(this);
_rowGroupHeaderPropertyNameAlternative = Properties.Resources.DefaultRowGroupHeaderPropertyNameAlternative;
_rowGroupHeaderStyles = new ObservableCollection<Style>();
_rowGroupHeaderStyles.CollectionChanged += RowGroupHeaderStyles_CollectionChanged;
_rowGroupHeaderStylesOld = new List<Style>();
this.RowGroupHeadersTable = new IndexToValueTable<DataGridRowGroupInfo>();
_collapsedSlotsTable = new IndexToValueTable<Visibility>();
_validationItems = new Dictionary<INotifyDataErrorInfo, string>();
_validationResults = new List<ValidationResult>();
_bindingValidationResults = new List<ValidationResult>();
_propertyValidationResults = new List<ValidationResult>();
_indeiValidationResults = new List<ValidationResult>();
this.ColumnHeaderInteractionInfo = new DataGridColumnHeaderInteractionInfo();
this.DisplayData = new DataGridDisplayData(this);
this.ColumnsInternal = CreateColumnsInstance();
this.RowHeightEstimate = DATAGRID_defaultRowHeight;
;
_rowHeaderDesiredWidth = ;
this.DataConnection = new DataGridDataConnection(this);
_showDetailsTable = new IndexToValueTable<Visibility>();
_focusInputDevice = FocusInputDeviceKind.None;
_proposedScrollBarsState = ScrollBarVisualState.NoIndicator;
_proposedScrollBarsSeparatorState = ScrollBarsSeparatorVisualState.SeparatorCollapsed;
;
_lastEstimatedRow = -;
_editingColumnIndex = -;
, -);
this.RowGroupHeaderHeightEstimate = DATAGRID_defaultRowHeight;
this.LastHandledKeyDown = VirtualKey.None;
this.DefaultStyleKey = typeof(DataGrid);
HookDataGridEvents();
}
2) ShowScrollBars()
DataGrid 控件中滚动条的处理方法。如果 AreAllScrollBarsCollapsed 为 true，则按照该规则简单处理；如果为 false，先按照 mouse 和 touch 的类型进行判断处理，再根据 UI 设置里的 AreSettingsEnablingAnimations 和 AreSettingsAutoHidingScrollBars 属性来切换滚动条的状态，调用 SwitchScrollBarsVisualStates 方法。
private void ShowScrollBars()
{
if (this.AreAllScrollBarsCollapsed)
{
_proposedScrollBarsState = ScrollBarVisualState.NoIndicator;
_proposedScrollBarsSeparatorState = ScrollBarsSeparatorVisualState.SeparatorCollapsedWithoutAnimation;
SwitchScrollBarsVisualStates(_proposedScrollBarsState, _proposedScrollBarsSeparatorState, false /*useTransitions*/);
}
else
{
if (_hideScrollBarsTimer != null && _hideScrollBarsTimer.IsEnabled)
{
_hideScrollBarsTimer.Stop();
_hideScrollBarsTimer.Start();
}
// Mouse indicators dominate if they are already showing or if we have set the flag to prefer them.
if (_preferMouseIndicators || _showingMouseIndicators)
{
if (this.AreBothScrollBarsVisible && (_isPointerOverHorizontalScrollBar || _isPointerOverVerticalScrollBar))
{
_proposedScrollBarsState = ScrollBarVisualState.MouseIndicatorFull;
}
else
{
_proposedScrollBarsState = ScrollBarVisualState.MouseIndicator;
}
_showingMouseIndicators = true;
}
else
{
_proposedScrollBarsState = ScrollBarVisualState.TouchIndicator;
}
// Select the proper state for the scroll bars separator square within the GroupScrollBarsSeparator group:
if (UISettingsHelper.AreSettingsEnablingAnimations)
{
// When OS animations are turned on, show the square when a scroll bar is shown unless the DataGrid is disabled, using an animation.
_proposedScrollBarsSeparatorState =
this.IsEnabled &&
_proposedScrollBarsState == ScrollBarVisualState.MouseIndicatorFull ?
ScrollBarsSeparatorVisualState.SeparatorExpanded : ScrollBarsSeparatorVisualState.SeparatorCollapsed;
}
else
{
// OS animations are turned off. Show or hide the square depending on the presence of a scroll bars, without an animation.
// When the DataGrid is disabled, hide the square in sync with the scroll bar(s).
if (_proposedScrollBarsState == ScrollBarVisualState.MouseIndicatorFull)
{
_proposedScrollBarsSeparatorState = this.IsEnabled ? ScrollBarsSeparatorVisualState.SeparatorExpandedWithoutAnimation : ScrollBarsSeparatorVisualState.SeparatorCollapsed;
}
else
{
_proposedScrollBarsSeparatorState = this.IsEnabled ? ScrollBarsSeparatorVisualState.SeparatorCollapsedWithoutAnimation : ScrollBarsSeparatorVisualState.SeparatorCollapsed;
}
}
if (!UISettingsHelper.AreSettingsAutoHidingScrollBars)
{
if (this.AreBothScrollBarsVisible)
{
if (UISettingsHelper.AreSettingsEnablingAnimations)
{
SwitchScrollBarsVisualStates(ScrollBarVisualState.MouseIndicatorFull, this.IsEnabled ? ScrollBarsSeparatorVisualState.SeparatorExpanded : ScrollBarsSeparatorVisualState.SeparatorCollapsed, true /*useTransitions*/);
}
else
{
SwitchScrollBarsVisualStates(ScrollBarVisualState.MouseIndicatorFull, this.IsEnabled ? ScrollBarsSeparatorVisualState.SeparatorExpandedWithoutAnimation : ScrollBarsSeparatorVisualState.SeparatorCollapsed, true /*useTransitions*/);
}
}
else
{
if (UISettingsHelper.AreSettingsEnablingAnimations)
{
SwitchScrollBarsVisualStates(ScrollBarVisualState.MouseIndicator, ScrollBarsSeparatorVisualState.SeparatorCollapsed, true /*useTransitions*/);
}
else
{
SwitchScrollBarsVisualStates(ScrollBarVisualState.MouseIndicator, this.IsEnabled ? ScrollBarsSeparatorVisualState.SeparatorCollapsedWithoutAnimation : ScrollBarsSeparatorVisualState.SeparatorCollapsed, true /*useTransitions*/);
}
}
}
else
{
SwitchScrollBarsVisualStates(_proposedScrollBarsState, _proposedScrollBarsSeparatorState, true /*useTransitions*/);
}
}
}
2. DataGridCellEditEndedEventArgs.cs
DataGrid 控件中有很多事件处理参数类，我们只看其中一个 DataGridCellEditEndedEventArgs 吧。很显然这个事件包含了 column row 和 editAction 三个变量，大家看到其他时间参数时，可以具体再分析。
public class DataGridCellEditEndedEventArgs : EventArgs
{
public DataGridCellEditEndedEventArgs(DataGridColumn column, DataGridRow row, DataGridEditAction editAction)
{
this.Column = column;
this.Row = row;
this.EditAction = editAction;
}
public DataGridColumn Column
{
get;
private set;
}
public DataGridEditAction EditAction
{
get;
private set;
}
public DataGridRow Row
{
get;
private set;
}
}
3. DataGridCellCollection.cs
DataGrid 控件中有很多数据类，我们看一个单元格集合类，可以看到集合中有 _cells，Count 变量，Insert 和 RemoveAt 方法等，处理逻辑都比较简单。
internal class DataGridCellCollection
{
private List<DataGridCell> _cells;
private DataGridRow _owningRow;
internal event EventHandler<DataGridCellEventArgs> CellAdded;
internal event EventHandler<DataGridCellEventArgs> CellRemoved;
public DataGridCellCollection(DataGridRow owningRow)
{
_owningRow = owningRow;
_cells = new List<DataGridCell>();
}
public int Count
{
get
{
return _cells.Count;
}
}
public IEnumerator GetEnumerator()
{
return _cells.GetEnumerator();
}
public void Insert(int cellIndex, DataGridCell cell)
{
Debug.Assert(cellIndex >= && cellIndex <= _cells.Count, "Expected cellIndex between 0 and _cells.Count inclusive.");
Debug.Assert(cell != null, "Expected non-null cell.");
cell.OwningRow = _owningRow;
_cells.Insert(cellIndex, cell);
if (CellAdded != null)
{
CellAdded(this, new DataGridCellEventArgs(cell));
}
}
public void RemoveAt(int cellIndex)
{
DataGridCell dataGridCell = _cells[cellIndex];
_cells.RemoveAt(cellIndex);
dataGridCell.OwningRow = null;
if (CellRemoved != null)
{
CellRemoved(this, new DataGridCellEventArgs(dataGridCell));
}
}
public DataGridCell this[int index]
{
get
{
|| index >= _cells.Count)
{
, true, _cells.Count, false);
}
return _cells[index];
}
}
}
4. DataGridCell.cs
DataGrid 控件的单元格类，处理比较简单，我们通过构造方法来看一下类中都涉及到哪些事件的处理；可以看到，光标的一系列处理都有涉及。
public DataGridCell()
{
this.IsTapEnabled = true;
this.AddHandler(UIElement.TappedEvent, new TappedEventHandler(DataGridCell_PointerTapped), true /*handledEventsToo*/);
this.PointerCanceled += new PointerEventHandler(DataGridCell_PointerCanceled);
this.PointerCaptureLost += new PointerEventHandler(DataGridCell_PointerCaptureLost);
this.PointerPressed += new PointerEventHandler(DataGridCell_PointerPressed);
this.PointerReleased += new PointerEventHandler(DataGridCell_PointerReleased);
this.PointerEntered += new PointerEventHandler(DataGridCell_PointerEntered);
this.PointerExited += new PointerEventHandler(DataGridCell_PointerExited);
this.PointerMoved += new PointerEventHandler(DataGridCell_PointerMoved);
DefaultStyleKey = typeof(DataGridCell);
}
总结
这里我们把 DataGrid 的 DataGrid 相关类介绍完成了，代码部分的 CollectionView，Utilities 和 DataGrid 就介绍完了。因为代码本身比较复杂，量也很大，所以我们只挑选了一小部分代码来分享，大家具体用到时可以再具体分析。
接下来我们会就 DataGrid 控件的各种编辑功能，各种自定义功能等做进一步的使用方式的分享。
最后，再跟大家安利一下 WindowsCommunityToolkit 的官方微博：https://weibo.com/u/6506046490, 大家可以通过微博关注最新动态。
衷心感谢 WindowsCommunityToolkit 的作者们杰出的工作，感谢每一位贡献者，Thank you so much, ALL WindowsCommunityToolkit AUTHORS !!!