// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
 
namespace System.Windows.Forms.Design;
 
/// <summary>
///  This is the designer for tree view controls. It inherits
///  from the base control designer and adds live hit testing
///  capabilities for the tree view control.
/// </summary>
internal class TreeViewDesigner : ControlDesigner
{
    private TVHITTESTINFO _tvhit;
    private DesignerActionListCollection? _actionLists;
    private TreeView? _treeView;
 
    public TreeViewDesigner()
    {
        AutoResizeHandles = true;
    }
 
    /// <summary>
    ///  Disposes of this object.
    /// </summary>
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            if (_treeView is not null)
            {
                _treeView.AfterExpand -= TreeViewInvalidate;
                _treeView.AfterCollapse -= TreeViewInvalidate;
                _treeView = null;
            }
        }
 
        base.Dispose(disposing);
    }
 
    /// <summary>
    ///  Allows your component to support a design time user interface. A TabStrip
    ///  control, for example, has a design time user interface that allows the user
    ///  to click the tabs to change tabs. To implement this, TabStrip returns
    ///  true whenever the given point is within its tabs.
    /// </summary>
    protected override bool GetHitTest(Point point)
    {
        point = Control.PointToClient(point);
        _tvhit.pt = point;
        PInvoke.SendMessage(Control, PInvoke.TVM_HITTEST, 0, ref _tvhit);
        return _tvhit.flags == TVHITTESTINFO_FLAGS.TVHT_ONITEMBUTTON;
    }
 
    public override void Initialize(IComponent component)
    {
        base.Initialize(component);
        _treeView = component as TreeView;
        Debug.Assert(_treeView is not null, "TreeView is null in TreeViewDesigner");
        if (_treeView is not null)
        {
            _treeView.AfterExpand += TreeViewInvalidate;
            _treeView.AfterCollapse += TreeViewInvalidate;
        }
    }
 
    private void TreeViewInvalidate(object? sender, TreeViewEventArgs e) => _treeView?.Invalidate();
 
    public override DesignerActionListCollection ActionLists => _actionLists ??= new DesignerActionListCollection
    {
        new TreeViewActionList(this)
    };
}