source: stable/HeuristicLab.ExtLibs/HeuristicLab.Netron/3.0.2672.12446/Netron.Diagramming.Core-3.0.2672.12446/Tools/HoverTool.cs

using System.Collections;
using System.Windows.Forms;

namespace Netron.Diagramming.Core {
  // ----------------------------------------------------------------------
  /// <summary>
  /// This tool allows entities to give feedback (e.g. via a change of 
  /// cursor) when the mouse is hovering over them.
  /// </summary>
  // ----------------------------------------------------------------------
  class HoverTool : AbstractTool, IMouseListener {

    #region Fields

    private IHoverListener currentListener = null;

    private IDiagramEntity previousHovered = null;


    #endregion

    #region Constructor

    // ------------------------------------------------------------------
    /// <summary>
    /// Initializes a new instance of the <see cref="T:HoverTool"/> class.
    /// </summary>
    /// <param name="name">The name of the tool.</param>
    // ------------------------------------------------------------------
    public HoverTool(string name)
      : base(name) {
    }

    #endregion

    #region Methods

    // ------------------------------------------------------------------
    /// <summary>
    /// Called when the tool is activated.
    /// </summary>
    // ------------------------------------------------------------------
    protected override void OnActivateTool() {


    }

    // ------------------------------------------------------------------
    /// <summary>
    /// Handles the mouse down event.
    /// </summary>
    /// <param name="e">The <see cref=
    /// "T:System.Windows.Forms.MouseEventArgs"/> instance containing 
    /// the event data.</param>
    // ------------------------------------------------------------------
    public bool MouseDown(MouseEventArgs e) {
      return false;
    }

    // ------------------------------------------------------------------
    /// <summary>
    /// Handles the mouse move event
    /// </summary>
    /// <param name="e">The <see cref=
    /// "T:System.Windows.Forms.MouseEventArgs"/> instance containing 
    /// the event data.</param>
    // ------------------------------------------------------------------
    public void MouseMove(MouseEventArgs e) {

      if (!IsSuspended && this.Enabled) {
        IHoverListener listener = null;

        CollectionBase<IDiagramEntity> paintables =
            this.Controller.Model.Paintables;
        IDiagramEntity entity;
        if (paintables.Count == 0) return;
        //going from top to the bottom of the z-order
        for (int k = paintables.Count - 1; k >= 0; k--) {
          entity = paintables[k];
          if (entity.Hit(e.Location)) //we caught an entity
                    {
            //unhover the previous, if any
            if (previousHovered != null) {
              previousHovered.Hovered = false;
            }

            //tell the current one it's being hovered
            entity.Hovered = true;

            //fetch the hovering service, if defined
            listener = entity.GetService(
                typeof(IHoverListener)) as IHoverListener;
            if (listener != null) //the caught entity does listen
                        {
              if (currentListener == listener) //it's the same as the previous time
                listener.MouseHover(e);
              else //we moved from one entity to another listening entity
                            {
                if (currentListener != null) //tell the previous entity we are leaving
                  currentListener.MouseLeave(e);
                listener.MouseEnter(e); //tell the current one we enter
                currentListener = listener;
              }
            } else //the caught entity does not listen
                        {
              if (currentListener != null) {
                currentListener.MouseLeave(e);
                currentListener = null;
              }
            }
            previousHovered = entity;//remember, for the next time
            return; //if another entity is listening underneath this entity it will not receive the notification
          }
        }
        if (currentListener != null) {
          currentListener.MouseLeave(e);
          currentListener = null;
        }
        //unhover the previous, if any
        if (previousHovered != null)
          previousHovered.Hovered = false;

      }
    }

    // ------------------------------------------------------------------
    /// <summary>
    /// Handles the mouse up event.
    /// </summary>
    /// <param name="e">The <see cref=
    /// "T:System.Windows.Forms.MouseEventArgs"/> instance containing 
    /// the event data.</param>
    // ------------------------------------------------------------------
    public void MouseUp(MouseEventArgs e) {

    }
    #endregion
  }

}