aistudio-wpf-diagram/AIStudio.Wpf.DiagramDesigner/Controls/BlockDragThumb.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Input;
using System.Windows.Media;
using AIStudio.Wpf.DiagramDesigner.Geometrys;

namespace AIStudio.Wpf.DiagramDesigner.Controls
{
    public class BlockDragThumb : DragThumb
    {
        BlockDesignerItemViewModel DesignerItem
        {
            get
            {
                return DataContext as BlockDesignerItemViewModel;
            }
        }

        private Point? firstPoint;
        protected override void OnPreviewMouseLeftButtonDown(MouseButtonEventArgs e)
        {
            base.OnPreviewMouseLeftButtonDown(e);
            if (e.LeftButton == MouseButtonState.Pressed &&  firstPoint == null)
            {
                firstPoint = e.GetPosition(this);
                DesignerItem.BeforeExecute();
            }
        }

        protected override void OnPreviewMouseLeftButtonUp(MouseButtonEventArgs e)
        {
            base.OnPreviewMouseLeftButtonDown(e);

            if (firstPoint == e.GetPosition(this))
            {              
                DesignerItem.EditCommand?.Execute(e.GetPosition(this));
                firstPoint = null;
            }

        }

    }
}