source: branches/HeuristicLab.Problems.GrammaticalOptimization/DynamicDataDisplay/Charts/Shapes/DraggablePoint.xaml.cs @ 13847

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Controls.Primitives;
using Microsoft.Research.DynamicDataDisplay;

namespace Microsoft.Research.DynamicDataDisplay.Charts.Shapes
{
  /// <summary>
  /// Represents a simple draggable point with position bound to point in viewport coordinates, which allows to drag iself by mouse.
  /// </summary>
  public partial class DraggablePoint : PositionalViewportUIContainer
  {
    /// <summary>
    /// Initializes a new instance of the <see cref="DraggablePoint"/> class.
    /// </summary>
    public DraggablePoint()
    {
      InitializeComponent();

      ViewportPanel.SetX(this, Position.X);
      ViewportPanel.SetY(this, Position.Y);
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DraggablePoint"/> class.
    /// </summary>
    /// <param name="position">The position of DraggablePoint.</param>
    public DraggablePoint(Point position)
      : this()
    {
      Position = position;
    }

    bool dragging = false;
    Point dragStart;
    Vector shift;
    protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
    {
      if (Plotter == null)
        return;

      dragStart = e.GetPosition(Plotter.ViewportPanel).ScreenToData(Plotter.Viewport.Transform);
      shift = Position - dragStart;
      dragging = true;
    }

    protected override void OnMouseLeave(MouseEventArgs e)
    {
      ReleaseMouseCapture();
      dragging = false;
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {
      if (!dragging)
      {
        if (IsMouseCaptured)
          ReleaseMouseCapture();

        return;
      }

      if (!IsMouseCaptured)
        CaptureMouse();

      Point mouseInData = e.GetPosition(Plotter.ViewportPanel).ScreenToData(Plotter.Viewport.Transform);

      if (mouseInData != dragStart)
      {
        Position = mouseInData + shift;
        e.Handled = true;
      }
    }

    protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
    {
      if (dragging)
      {
        dragging = false;
        if (IsMouseCaptured)
        {
          ReleaseMouseCapture();
          e.Handled = true;
        }
      }
    }
  }
}