Windows 8的：如何撤消和重做墨水使用内置的墨迹书写功能？(Windows 8: How to

基于微软简化墨样品，我实现了墨代码在我的应用程序： http://code.msdn.microsoft.com/windowsapps/Input-simplified-ink-sample-11614bbf/view/SourceCode

首先，我做了一个类（平局/删除/清除），这样可以节省操作的数据：

public enum eInkOperation
{
    Draw,
    Delete,
    None
}

public class InkOperation
{
    public InkStroke Stroke { get; set; } //requred for drawing from undo
    public eInkOperation Operation { get; set; }

    public InkOperation(InkStroke stroke, eInkOperation inkOperation)
    {
        Stroke = stroke.Clone(); //needs to be cloned for AddStroke to work
        Operation = inkOperation;
    }
}

然后我做了撤销墨操作的一个栈，一个用于重做操作

//stack of normal operations
Stack<InkOperation> _undoStack = new Stack<InkOperation>(); 
//Undo action will pop them off of the undo stack and push them onto the redo stack
Stack<InkOperation> _redoStack = new Stack<InkOperation>();

当用户撤消中风我推到重做堆栈上，并从这些方法的inkmanager删除：

private void RedoStackPush(InkOperation inkOperation)
{
    inkOperation.Stroke = inkOperation.Stroke.Clone();
    _redoStack.Push(inkOperation);
}

  private void DeleteStroke(InkStroke stroke)
    {                            
        stroke = inkManager.GetStrokes().Last();
        stroke.Selected = true;
        inkManager.DeleteSelected();
    }

然后，当用户点击重做，笔划被弹出重做堆栈和使用该方法绘制：

private void DrawStroke(InkStroke stroke)
{
        if (stroke!=null)
        {
            inkManager.Mode = InkManipulationMode.Inking;
            inkManager.AddStroke(stroke);
        }
        renderer.Clear(); //this renderer object smooths the strokes
        //and adds them as Path objects to the desired control (Grid, etc)
        renderer.AddInk(inkManager.GetStrokes());
}

这所有的作品，行程显示回电网。 然而，当我试图抹掉新重绘行程我得到这个异常：

AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

这发生在：

public void PointerMoved(PointerRoutedEventArgs e)
{
    try
    {
        var pointerPoint = e.GetCurrentPoint(_inkingArea);
        var pointerEventType = InkHelpers.GetPointerEventType(e);
        if (pointerId == (int)pointerPoint.PointerId)
        {
            switch (inkManager.Mode)
            {
                case InkManipulationMode.Inking:
                case InkManipulationMode.Selecting:
                    //process intermediate points
                    var intermediatePoints = e.GetIntermediatePoints(_inkingArea);
                    for (int i = intermediatePoints.Count - 1; i >= 0; i--)
                    {
                        inkManager.ProcessPointerUpdate(intermediatePoints[i]);
                    }
                    //live rendering
                    renderer.UpdateLiveRender(pointerPoint);
                    break;
                case InkManipulationMode.Erasing:
                    //check if something has been erased
                    //in erase mode InkManager.ProcessPointerUpdate returns an invalidate rectangle:
                    //if it is not degenerate, something has been erased
                    //in erase mode don't bother processing intermediate points

                    //If inkManager.ProcessPointerUpdate throws an exception, it crashes the app regardless of any catches
                    Rect invalidateRect = (Rect)inkManager.ProcessPointerUpdate(e.GetCurrentPoint(_inkingArea));
                    if (invalidateRect.Height != 0 && invalidateRect.Width != 0)
                    {
                        //we don't know what has been erased so we clear the render
                        //and add back all the ink saved in the ink manager
                        renderer.Clear();

                        var remainingStrokes = inkManager.GetStrokes();
                        renderer.AddInk(remainingStrokes);
                    }
                    break;
                default:
                    break;
            }
        }
    }
    catch (Exception) { }
}

在这条线：

Rect invalidateRect = (Rect)inkManager.ProcessPointerUpdate(e.GetCurrentPoint(_inkingArea));

我认为问题的关键在于增加招油墨经理的过程。 我试图使一个新的行程，甚至从InkStroke继承，使之可定制，但InkStroke类是密封的，它不会有一个构造函数。 唯一的是，我发现复制这是应该做inkStroke.Clone（）。 但即使这样，试图重绘删除油墨（撤消删除行程）时，有它的问题。

我试图使这个问题尽可能明确使用最少的代码量，以避免混淆，所以让我知道，如果它是不够的。

此外，在这个问题我专注于撤销平局行动。 撤消擦除操作（甚至“清除所有”行动）有其自身的问题，因为我不能让InkStroke对象的副本。

预先感谢您的时间和考虑。

Answer 1:

见这从MSDN线程，它可能会有所帮助。

文章来源: Windows 8: How to undo & redo ink using built in Inking functionality?