详解WPF的InkCanvas选择模式

// xaml
<Grid>
  <InkCanvas x:Name="inkCanvas"/>
  <Button x:Name="btnChangeMode" Content="select" Click="Button_Click"
      Width="50" Height="30" HorizontalAlignment="Left" VerticalAlignment="Bottom" Margin="10"/>
</Grid>

// cs
private void Button_Click(object sender, RoutedEventArgs e)
{
	if(btnChangeMode.Content == "select")
	{
    inkCanvas.EditingMode = InkCanvasEditingMode.Select;
    btnChangeMode.Content = "write";
	}
	else
	{
    inkCanvas.EditingMode = InkCanvasEditingMode.Ink;
    btnChangeMode.Content = "select";
	}
}

protected override void OnRender(DrawingContext drawingContext)
{
  DrawBackground(drawingContext);

  Rect rectWireFrame = GetWireFrameRect()
  if(!rectWireFrame.IsEmpty)
  {
    drawingContext.DrawRectangle(null, _adornerBorderPen, rectWireFrame);

    DrawHandles(drawingContext, rectWireFrame);
  }
}

protected override void OnRender(DrawingContext drawingContext)
{
  drawingContext.DrawRectangle(null, _adornerBorderPen,
    new Rect(CornerResizeHandleSize / 2, CornerResizeHandleSize / 2,
    _frameSize.Width - CornerResizeHandleSize, _frameSize.Height - CornerResizeHandleSize));
}

internal override void OnPreApplyTemplate()
{
  base.OnPreApplyTemplate();

  // Build our visual tree here.
  // <InkCanvas>
  //   <AdornerDecorator>
  //     <InkPresenter>
  //       <InnerCanvas/>
  //       <ContainerVisual/>
  //       <HostVisual/>
  //     </InkPresenter>
  //     <AdornerLayer>
  //       <InkCanvasSelectionAdorner/>
  //       <InkCanvasFeedbackAdorner/>
  //     </AdornerLayer>
  //   </AdornerDecorator>
  // </InkCanvas>

  if(_localAdornerDecorator == null)
  {
    _localAdornerDecorator = new AdornerDecorator();
    InkPresenter inkPresenter = InkPresenter;

    AddVisualChild(_localAdornerDecorator);
    _localAdornerDecorator.Child = inkPresenter;
    inkPresenter.Child = InnerCanvas;

    _localAdornerDecorator.AdornerLayer.Add(SelectionAdorner);
  }
}

internal InkCanvasSelectionAdorner SelectionAdorner
{
  get
  {
    if(_selectionAdorner == null)
    {
      _selectionAdorner = new InkCanvasSelectionAdorner(InnerCanvas);

      Binding activedEditingModeBinding = new Binding();
      activedEditingModeBinding.Path = new PropertyPath(InkCanvas.ActiveEditingModeProperty);
      activedEditingModeBinding.Mode = BindingMode.OneWay;
      activedEditingModeBinding.Source = this;
      activedEditingModeBinding.Converter = new ActiveEditingMode2VisibilityConverter();
      _selectionAdorner.SetBinding(UIElement.VisibilityProperty, activedEditingModeBinding);
    }

    return _selectionAdorner;
  }
}

// InkCanvasFeedbackAdorner
internal InkCanvasFeedbackAdorner(InkCanvas inkCanvas)
  : base((inkCanvas != null ? inkCanvas.InnerCanvas : null))
  {...}

protected override void OnActive()
{
  // ...
  InkCanvas.InkCanvasSelection.StartFeedbackAdorner(_selectionRect, _hitResult);

  InkCanvas.SelectionAdorner.AddHandler(Mouse.MouseUpEvent, new MouseButtonEventHandler(OnMouseUp));
  InkCanvas.SelectionAdorner.AddHandler(Mouse.MouseMoveEvent, new MouseEventHandler(OnMouseMove));
  InkCanvas.SelectionAdorner.AddHandler(Mouse.LostMouseCaptureEvent, new MouseEventHandler(OnLostMouseCapture));
}

private void OnMouseMove(object sender, MouseEventArgs args)
{
  // ...
  InkCanvas.InkCanvasSelection.UpdateFeedbackAdorner(newRect);
  // ...
}