NoteMAUI/GraphPage.xaml.cs

using System.Diagnostics;
using System.Linq;

namespace NotesDataAnalyst
{
    public partial class GraphPage : ContentPage
    {
        private PointF _initialNodePosition;
        private PointF _initialTouchPosition;
        private SizeF _initialNodeSize;
        private readonly List<GraphNode> _nodes = new();
        private readonly List<GraphConnection> _connections = new();
        private GraphNode _selectedNode;
        private bool _isResizing = false;

        public GraphPage()
        {
            InitializeComponent();

            var graphDrawable = new GraphDrawable(_nodes, _connections);
            canvasView.Drawable = graphDrawable;

            var panGesture = new PanGestureRecognizer();
            panGesture.PanUpdated += OnPanUpdated;
            canvasView.GestureRecognizers.Add(panGesture);

            var tapGesture = new TapGestureRecognizer();
            tapGesture.Tapped += OnCanvasTapped;
            canvasView.GestureRecognizers.Add(tapGesture);
        }

        private async void OnResizeNodeClicked(object sender, EventArgs e)
        {
            // Проверяем, выбрана ли нода
            if (_selectedNode == null)
            {
                await DisplayAlert("Ошибка", "Сначала выберите ноду", "OK");
                return;
            }

            // Открываем диалог для ввода новых размеров
            var result = await DisplayPromptAsync("Изменить размер", "Введите ширину и высоту",
                                                  initialValue: $"{_selectedNode.Size.Width} x {_selectedNode.Size.Height}",
                                                  keyboard: Keyboard.Numeric);

            if (string.IsNullOrEmpty(result)) return;

            // Разбиваем введенное значение на ширину и высоту
            var dimensions = result.Split('x');
            if (dimensions.Length == 2 &&
                double.TryParse(dimensions[0].Trim(), out double width) &&
                double.TryParse(dimensions[1].Trim(), out double height))
            {
                // Обновляем размеры ноды
                _selectedNode.Size = new Size(width, height);
                canvasView.Invalidate(); // Перерисовываем канву
            }
            else
            {
                await DisplayAlert("Ошибка", "Неверный формат. Введите значения в формате ширина x высота.", "OK");
            }
        }


        private async void OnAddNodeClicked(object sender, EventArgs e)
        {

            var newNode = new GraphNode
            {
                Text = "Новая нода",
                Position = new Point(100, 200),
                Size = new Size(100, 50),

            };

            _nodes.Add(newNode);
            canvasView.Invalidate();
        }

        private void OnChildClicked(object sender, EventArgs e)
        {
            if (_selectedNode != null)
            {
                var childNode = new GraphNode
                {
                    Text = "Child Node",
                    Position = new Point(_selectedNode.Position.X + 100, _selectedNode.Position.Y + 70),
                    Size = _selectedNode.Size,
                    BackgroundColor = Colors.Gray,
                };
                _nodes.Add(childNode);
                _connections.Add(new GraphConnection { FromNode = _selectedNode, ToNode = childNode });
                canvasView.Invalidate();
            }
            else
            {
                Debug.WriteLine("Сначала выберите ноду");
            }
        }


        private void OnCanvasTapped(object sender, TappedEventArgs e)
        {
            var tapPosition = e.GetPosition((View)sender);
            _selectedNode = null;

            if (tapPosition.HasValue)
            {
                var touchPoint = new PointF((float)tapPosition.Value.X, (float)tapPosition.Value.Y);
                _selectedNode = _nodes.FirstOrDefault(node => IsPointInsideNode(touchPoint, node));

                foreach (var node in _nodes)
                    node.IsActive = node == _selectedNode;

                canvasView.Invalidate();
            }
        }

        private void OnPanUpdated(object sender, PanUpdatedEventArgs e)
        {
            if (_selectedNode == null) return;

            if (e.StatusType == GestureStatus.Started)
            {
                _initialNodePosition = _selectedNode.Position;
                _initialTouchPosition = new PointF((float)e.TotalX, (float)e.TotalY);
                _initialNodeSize = _selectedNode.Size;

                _isResizing = IsOnResizeHandle(_selectedNode, _initialTouchPosition);
            }
            else if (e.StatusType == GestureStatus.Running)
            {
                var deltaX = (float)e.TotalX - _initialTouchPosition.X;
                var deltaY = (float)e.TotalY - _initialTouchPosition.Y;

                if (_isResizing)
                {
                    ResizeNode(_selectedNode, deltaX, deltaY);
                }
                else
                {
                    _selectedNode.Position = new PointF(
                        _initialNodePosition.X + deltaX,
                        _initialNodePosition.Y + deltaY
                    );
                }

                canvasView.Invalidate();
            }
            else if (e.StatusType == GestureStatus.Completed)
            {
                _isResizing = false;
            }
        }

        private void ResizeNode(GraphNode node, double deltaX, double deltaY)
        {
            const double minSize = 50.0;

            if (_isResizing)
            {
                _selectedNode.Size = new Size(
                    Math.Max(minSize, _initialNodeSize.Width + deltaX),
                    Math.Max(minSize, _initialNodeSize.Height + deltaY)
                );
            }
        }

        private bool IsOnResizeHandle(GraphNode node, PointF point)
        {
            const float handleSize = 20f;

            var resizeHandleRect = new RectF(
                (float)(node.Position.X + node.Size.Width - handleSize),
                (float)(node.Position.Y + node.Size.Height - handleSize),
                handleSize, handleSize
            );

            return resizeHandleRect.Contains(point);
        }

        private bool IsPointInsideNode(PointF point, GraphNode node)
        {
            return point.X >= node.Position.X &&
                   point.X <= node.Position.X + node.Size.Width &&
                   point.Y >= node.Position.Y &&
                   point.Y <= node.Position.Y + node.Size.Height;
        }
    }
}