SHJX_GM/SHJX.Service.WorkFlowEdit/Common/DragDropTool.cs

using Aga.Diagrams;
using Aga.Diagrams.Tools;
using System.Linq;
using System.Windows;

namespace FlowWorkEditDemo
{
    class DragDropTool : IDragDropTool
    {
        DiagramView _view;
        FlowchartModel _model;
        int _row, _column;

        public DragDropTool(DiagramView view, FlowchartModel model)
        {
            _view = view;
            _model = model;
        }

        public void OnDragEnter(DragEventArgs e)
        {
        }

        public void OnDragOver(DragEventArgs e)
        {
            e.Effects = DragDropEffects.None;
            if (e.Data.GetDataPresent(typeof(NodeKinds)))
            {
                var position = e.GetPosition(_view);
                _column = (int)(position.X / _view.GridCellSize.Width);
                _row = (int)(position.Y / _view.GridCellSize.Height);
                if (_column >= 0 && _row >= 0)
                    if (_model.Nodes.Where(p => p.Column == _column && p.Row == _row).Count() == 0)
                        e.Effects = e.AllowedEffects;
            }
            e.Handled = true;
        }

        public void OnDragLeave(System.Windows.DragEventArgs e)
        {
        }

        public void OnDrop(System.Windows.DragEventArgs e)
        {
            var node = new FlowNode((NodeKinds)e.Data.GetData(typeof(NodeKinds)));
            node.Row = _row;
            node.Column = _column;
            _model.Nodes.Add(node);
            e.Handled = true;
        }
    }
}