Question

我有一个方案,有两部WPF树图,允许在两者之间ging积和 dropping落。问题在于,它可能无意在树苗上开立/关闭项目,因为把 mo改成一只平子,同时保留左 mo子,会引发rag/ drop功能。是否有办法说明在考虑rag/ drop之前, mo应走多少?

Answer 1

这里有一个系统参数。如果是,

Point down = {where mouse down event happened}
Point current = {position in the MouseMove eventargs}

那么,如果是这样的话,则该运动会缩短了最低限度的距离。

Math.Abs(current.X - down.X) >= SystemParameters.MinimumHorizontalDragDistance ||
Math.Abs(current.Y - down.Y) >= SystemParameters.MinimumVerticalDragDistance

Answer 2

仅仅在你确定拖延何时开始的法典中打上了一点缓冲。

flag mouse down
on mouse move - check for mouse down.. if yes, check to see if its moved farther than whatever buffer you specify (3 pixels is probably good)
if it has, start the drag.

Answer 3

在ts article for Drag and Drop implementation, 您将不得不处理2次 mo动事,以便拖延拖到 mo运动已经走了一定距离。首先,增加一名手提车,储存与你控制有关的最初改变立场。承诺使用MouseDown活动,因为这是一个泡沫活动,可能由儿童控制处理,然后才能获得你的控制。

public class DraggableControl : UserControl
{
  private Point? _initialMousePosition;

  public DraggableControl()
  {
    PreviewMouseDown += OnPreviewMouseDown;
  }

  private void OnPreviewMouseDown(object sender, MouseButtonEventArgs e) {
    _initialMousePosition = e.GetPosition(this);
  }

此外,还处理使用着手检查迁移距离,并最终启动拖拉行动:

  ...
  public DraggableControl()
  {
    ...
    MouseMove += OnMouseMove;
  }
  ...
  private void OnMouseMove(object sender, MouseEventArgs e)
  {
    // Calculate distance between inital and updated mouse position
    var movedDistance = (_initialMousePosition - e.GetPosition(this)).Length;
    if (movedDistance > yourThreshold)
    {
      DragDrop.DoDragDrop(...);
    }
  }
}

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