WPF设置框选不规则图形，并把框选范围内的不规则图形内容的图形显示出来



前端XAML代码

<Window x:Class="WpfApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp1"
        mc:Ignorable="d"
        Title="MainWindow" Height="600" Width="600">
    <Canvas Name="drawingCanvas" Background="LightGray" MouseLeftButtonDown="Canvas_MouseLeftButtonDown" MouseMove="Canvas_MouseMove" MouseLeftButtonUp="Canvas_MouseLeftButtonUp">
        <!-- This is the canvas where the irregular shape will be drawn -->
    </Canvas>
</Window>

后端代码

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;

namespace WpfApp1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private bool isDrawing = false;
        private PathFigure currentPathFigure;
        private List<PathFigure> pathFigures = new List<PathFigure>();
        private Path path;

        public MainWindow()
        {
            InitializeComponent();

            Loaded += MainWindow_Loaded;
        }

        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            InitializeDrawingCanvas();
            DrawGrid(); // Draw the 10x10 grid
        }

        private void InitializeDrawingCanvas()
        {
            path = new Path
            {
                Stroke = Brushes.Black,
                StrokeThickness = 2
            };

            drawingCanvas.Children.Add(path);
        }

        private void Canvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            isDrawing = true;

            pathFigures = new List<PathFigure>();
            currentPathFigure = new PathFigure();
            currentPathFigure.StartPoint = e.GetPosition(drawingCanvas);

            pathFigures.Add(currentPathFigure);

            path.Data = new PathGeometry(pathFigures);
        }

        private void Canvas_MouseMove(object sender, MouseEventArgs e)
        {
            if (isDrawing)
            {
                // Remove the last line segment (connecting to the start point)
                if (currentPathFigure.Segments.Count > 1)
                    currentPathFigure.Segments.RemoveAt(currentPathFigure.Segments.Count - 1);

                currentPathFigure.Segments.Add(new LineSegment(e.GetPosition(drawingCanvas), true));

                // Add a new line segment connecting to the start point
                currentPathFigure.Segments.Add(new LineSegment(currentPathFigure.StartPoint, true));

                path.Data = new PathGeometry(pathFigures);
            }
        }

        private void Canvas_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            isDrawing = false;

            UpdateDrawGrid();

            pathFigures = new List<PathFigure>();
            currentPathFigure = new PathFigure();
        }

        public bool IsRectInsidePath(Rect rect)
        {
            if (path.Data.FillContains(new Point(rect.X, rect.Y)) ||
                path.Data.FillContains(new Point(rect.X + rect.Width, rect.Y)) ||
                path.Data.FillContains(new Point(rect.X, rect.Y + rect.Height)) ||
                path.Data.FillContains(new Point(rect.X + rect.Width, rect.Y + rect.Height)))
            {
                return true;
            }
            return false;
        }

        static bool IsPointInsidePath(Point point, Path path)
        {
            // 判断点是否在不规则图形中
            return path.Data.FillContains(point);
        }

        private void UpdateDrawGrid()
        {
            double cellWidth = drawingCanvas.ActualWidth / 50;
            double cellHeight = drawingCanvas.ActualHeight / 50;

            int index = 0;
            for (int i = 0; i < 50; i++)
            {
                for (int j = 0; j < 50; j++)
                {
                    var rect = new Rect(i * cellWidth, j * cellHeight, cellWidth, cellHeight);
                    if (IsRectInsidePath(rect))
                    {
                        var list = GetAllChildControls(drawingCanvas);
                        foreach (var item in list)
                        {
                            if (item is Rectangle r)
                            {
                                if (r.Name == "Rect_" + index)
                                {
                                    r.Fill = Brushes.Red;
                                }
                            }
                        }
                    }
                    index++;
                }
            }
        }


        private void DrawGrid()
        {
            double cellWidth = drawingCanvas.ActualWidth / 50;
            double cellHeight = drawingCanvas.ActualHeight / 50;

            int index = 0;
            for (int i = 0; i < 50; i++)
            {
                for (int j = 0; j < 50; j++)
                {
                    Rectangle gridCell = new Rectangle
                    {
                        Name ="Rect_"+ index.ToString(),
                        Width = cellWidth,
                        Height = cellHeight,
                        Stroke = Brushes.Blue,
                        StrokeThickness = 0.5
                    };

                    Canvas.SetLeft(gridCell, i * cellWidth);
                    Canvas.SetTop(gridCell, j * cellHeight);

                    drawingCanvas.Children.Add(gridCell);
                    index++;
                }
            }
        }

        static List<UIElement> GetAllChildControls(DependencyObject parent)
        {
            var allChildControls = new System.Collections.Generic.List<UIElement>();

            // 使用递归遍历VisualTree获取所有子控件
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
            {
                var child = VisualTreeHelper.GetChild(parent, i);

                if (child is UIElement)
                {
                    allChildControls.Add(child as UIElement);
                }

                // 递归处理子控件的子控件
                allChildControls.AddRange(GetAllChildControls(child));
            }

            return allChildControls;
        }
    }
}