3rdpartylibs/fastreports.wpf/FastReport.Forms.WPF/Controls/TreeView.cs

using CustomControls;
using System.Windows.Controls;

namespace System.Windows.Forms
{
    public partial class TreeView : Control
    {
        private bool mouseMoved;
        private Point mouseDownPoint;
        private TreeNode selectedNodeAtMouseDown;
        private TreeNode nodeAtMouseDown;
        private TreeNode editedNode;
        private Timer labelEditTimer;
        private bool nodeDoubleClicked;

        protected new CustomControls.TreeView control { get; }

        public TreeNodeCollection Nodes { get; }

        public bool CheckBoxes
        {
            get => control.CheckBoxes == Visibility.Visible;
            set => control.CheckBoxes = value ? Visibility.Visible : Visibility.Collapsed;
        }

        private ImageList imageList;
        public ImageList ImageList
        {
            get => imageList;
            set
            {
                imageList = value;
                control.Images = value != null ? Visibility.Visible : Visibility.Collapsed;
                ResetImageList();
            }
        }

        public bool LabelEdit { get; set; }

        private TreeNode selectedNode;
        public TreeNode SelectedNode
        {
            get => selectedNode;
            set
            {
                if (value != selectedNode)
                {
                    if (value != null)
                    {
                        value.IsSelected = true;
                    }
                    else if (SelectedNode != null)
                    {
                        SelectedNode.IsSelected = false;
                    }
                    selectedNode = value;
                    
                    SelectItemHelper.Select(control, value);
                }
            }
        }

        public bool HideSelection
        {
            get => control.HideSelection;
            set => control.HideSelection = value;
        }

        public string PathSeparator { get; set; }

        public bool Sorted { get; set; } // TODO?

        // not applicable / ignored
        public int ImageIndex { get; set; }
        public int SelectedImageIndex { get; set; }
        public bool ShowRootLines { get; set; }
        public bool ShowPlusMinus { get; set; }
        public bool ShowLines { get; set; }
        public int Indent { get; set; }
        public bool RightToLeftLayout { get; set; }
        public bool HotTracking { get; set; }
        public int ItemHeight { get; set; }


        public event TreeViewEventHandler AfterCheck;
        public event TreeViewEventHandler AfterCollapse;
        public event TreeViewEventHandler AfterExpand;
        public event TreeViewEventHandler AfterSelect;
        public event TreeViewCancelEventHandler BeforeCheck;
        public event TreeViewCancelEventHandler BeforeCollapse;
        public event TreeViewCancelEventHandler BeforeExpand;
        public event TreeViewCancelEventHandler BeforeSelect;
        public event ItemDragEventHandler ItemDrag;
        public event TreeNodeMouseClickEventHandler NodeMouseClick;
        public event TreeNodeMouseClickEventHandler NodeMouseDoubleClick;
        public event NodeLabelEditEventHandler AfterLabelEdit;
        public event NodeLabelEditEventHandler BeforeLabelEdit;
        public new event MouseEventHandler MouseUp;
        public new event KeyEventHandler KeyDown;

        private void WireEvents()
        {
            control.AcceptEdit += (sender, e) => editedNode?.EndEdit(false);
            control.CancelEdit += (sender, e) => editedNode?.EndEdit(true);

            control.PreviewMouseDown += (sender, e) =>
            {
                mouseMoved = false;
                selectedNodeAtMouseDown = SelectedNode;
                mouseDownPoint = e.GetPosition(control);

                // do not allow change selection in MouseDown. Do it in MouseUp to be consistent with WinForms
                nodeAtMouseDown = NodeHitTest(mouseDownPoint);
                if (nodeAtMouseDown != null)
                {
                    e.Handled = true;
                    if (e.ClickCount == 2 && e.LeftButton == Input.MouseButtonState.Pressed)
                        nodeDoubleClicked = true;
                }
            };
            control.MouseMove += (sender, e) =>
            {
                if (e.LeftButton == Input.MouseButtonState.Pressed)
                {
                    var pos = e.GetPosition(control);
                    if (!mouseMoved && Math.Sqrt(Math.Pow(mouseDownPoint.X - pos.X, 2) + Math.Pow(mouseDownPoint.Y - pos.Y, 2)) > 5)
                    {
                        if (nodeAtMouseDown != null)
                        {
                            control.Focus();
                            OnItemDrag(new ItemDragEventArgs(MouseButtons.Left, nodeAtMouseDown));
                        }
                        mouseMoved = true;
                    }
                }
            };
            control.MouseUp += (sender, e) =>
            {
                if (!mouseMoved)
                {
                    var pos = e.GetPosition(control);
                    var node = NodeHitTest(pos);
                    if (node != null)
                    {
                        // without this, editing label won't work correctly
                        control.Focus();

                        mouseMoved = true; // workaround: do not allow MouseMove if context menu was shown in the OnNodeMouseClick

                        if (nodeDoubleClicked)
                        {
                            StopLabelEditTimer();
                            OnNodeMouseDoubleClick(new TreeNodeMouseClickEventArgs(nodeAtMouseDown, MouseButtons.Left, 0, (int)(mouseDownPoint.X * DpiScale), (int)(mouseDownPoint.Y * DpiScale)));
                        }
                        else
                        {
                            OnNodeMouseClick(new TreeNodeMouseClickEventArgs(node, Helper.GetMouseButton(e.ChangedButton), 0, (int)(pos.X * DpiScale), (int)(pos.Y * DpiScale)));
                        }
                        OnMouseUp(Helper.GetMouseEventArgs(control, e));

                        if (e.ChangedButton == Input.MouseButton.Left)
                        {
                            node.IsSelected = true;

                            if (LabelEdit && !nodeDoubleClicked && selectedNodeAtMouseDown == node && NodeHitTest(pos, true) != null)
                                StartLabelEditTimer();
                        }
                        nodeDoubleClicked = false;
                    }
                }
            };
            control.PreviewKeyDown += (sender, e) =>
            {
                if (editedNode == null)
                {
                    var args = Helper.GetKeyEventArgs(e);
                    OnKeyDown(args);
                    if (args.Handled)
                        e.Handled = true;
                }
            };
        }

        private TreeNode NodeHitTest(Point point, bool textOnly = false)
        {
            var item = control.InputHitTest(point);
            if (item is TextBlock txt && txt.Name == "PART_TextBlock")
            {
                var node = txt.DataContext as TreeNode;
                if (node != null)
                {
                    var rect = txt.BoundsRelativeTo(control);
                    node.SetBounds(new Drawing.Rectangle((int)(rect.Left * DpiScale), (int)(rect.Top * DpiScale), (int)(rect.Width * DpiScale), (int)(rect.Height * DpiScale)));
                }
                return node;
            }
            if (!textOnly && item is Image img && img.Name == "PART_Image")
                return img.DataContext as TreeNode;
            return null;
        }

        private void ResetImageList()
        {
            foreach (var node in Nodes)
                node.ResetImageSourceAll();
        }

        private void StartLabelEditTimer()
        {
            if (labelEditTimer == null)
                labelEditTimer = new Timer();
            labelEditTimer.Interval = SystemInformation.DoubleClickTime;
            labelEditTimer.Start();
            labelEditTimer.Tick += (s, e) =>
            {
                labelEditTimer.Stop();
                selectedNodeAtMouseDown?.BeginEdit();
            };
        }

        private void StopLabelEditTimer()
        {
            if (labelEditTimer != null)
            {
                labelEditTimer.Stop();
                labelEditTimer = null;
            }
        }

        protected new virtual void OnMouseUp(MouseEventArgs e) => MouseUp?.Invoke(this, e);

        protected new virtual void OnKeyDown(KeyEventArgs e) => KeyDown?.Invoke(this, e);

        protected virtual void OnAfterCheck(TreeViewEventArgs e) => AfterCheck?.Invoke(this, e);

        protected virtual void OnAfterCollapse(TreeViewEventArgs e) => AfterCollapse?.Invoke(this, e);

        protected virtual void OnAfterExpand(TreeViewEventArgs e) => AfterExpand?.Invoke(this, e);

        protected virtual void OnAfterSelect(TreeViewEventArgs e) => AfterSelect?.Invoke(this, e);

        protected virtual void OnBeforeCheck(TreeViewCancelEventArgs e) => BeforeCheck?.Invoke(this, e);

        protected virtual void OnBeforeCollapse(TreeViewCancelEventArgs e) => BeforeCollapse?.Invoke(this, e);

        protected virtual void OnBeforeExpand(TreeViewCancelEventArgs e) => BeforeExpand?.Invoke(this, e);

        protected virtual void OnBeforeSelect(TreeViewCancelEventArgs e) => BeforeSelect?.Invoke(this, e);

        protected virtual void OnItemDrag(ItemDragEventArgs e) => ItemDrag?.Invoke(this, e);

        protected virtual void OnNodeMouseDoubleClick(TreeNodeMouseClickEventArgs e) => NodeMouseDoubleClick?.Invoke(this, e);
        
        protected virtual void OnNodeMouseClick(TreeNodeMouseClickEventArgs e) => NodeMouseClick?.Invoke(this, e);

        protected virtual void OnAfterLabelEdit(NodeLabelEditEventArgs e) => AfterLabelEdit?.Invoke(this, e);

        protected virtual void OnBeforeLabelEdit(NodeLabelEditEventArgs e) => BeforeLabelEdit?.Invoke(this, e);

        internal bool DoNodeSelect(TreeNode node)
        {
            var args = new TreeViewCancelEventArgs(node, false, TreeViewAction.Unknown);
            OnBeforeSelect(args);
            if (args.Cancel)
                return false;

            selectedNode = node;
            OnAfterSelect(new TreeViewEventArgs(node));
            return true;
        }

        internal void DoAfterCheck(TreeViewEventArgs e) => OnAfterCheck(e);

        internal void DoAfterCollapse(TreeViewEventArgs e) => OnAfterCollapse(e);

        internal void DoAfterExpand(TreeViewEventArgs e) => OnAfterExpand(e);

        internal void DoBeforeCheck(TreeViewCancelEventArgs e) => OnBeforeCheck(e);

        internal void DoBeforeExpand(TreeViewCancelEventArgs e) => OnBeforeExpand(e);

        internal void DoBeforeCollapse(TreeViewCancelEventArgs e) => OnBeforeCollapse(e);

        internal void DoOnAfterLabelEdit(NodeLabelEditEventArgs e) => OnAfterLabelEdit(e);

        internal void DoOnBeforeLabelEdit(NodeLabelEditEventArgs e) => OnBeforeLabelEdit(e);

        internal void SetEditedNode(TreeNode node) => editedNode = node;

        public void ExpandAll()
        {
            foreach (var node in Nodes)
                node.ExpandAll();
        }

        public void CollapseAll()
        {
            foreach (var node in Nodes)
                node.CollapseAll();
        }

        public TreeNode GetNodeAt(Drawing.Point point) => GetNodeAt(point.X, point.Y);

        public TreeNode GetNodeAt(int x, int y) => NodeHitTest(new Point(x / DpiScale, y / DpiScale));

        public void BeginUpdate() { Nodes.RaiseListChangedEvents = false; }

        public void EndUpdate() { Nodes.RaiseListChangedEvents = true; Nodes.ResetBindings(); }

        public TreeView()
        {
            Nodes = new(null);
            Nodes.SetOwner(this);

            control = new();
            control.ItemsSource = Nodes;
            VirtualizingPanel.SetIsVirtualizing(control, true);
            VirtualizingPanel.SetVirtualizationMode(control, VirtualizationMode.Recycling);

            WireEvents();
            // do this after wiring events. Some event handlers inside SetControl may set the Handled flag to true which prevents additional event handlers to fire up
            SetControl(control);

            PathSeparator = "\\";
        }
    }
}