Question

I have built a simple StreamGeometry, using MSDN example:

StreamGeometry geometry = new StreamGeometry();
geometry.FillRule = FillRule.EvenOdd;
using (StreamGeometryContext ctx = geometry.Open())
{
     ctx.BeginFigure(new Point(10, 100), true /* is filled */, true /* is closed */);
     ctx.LineTo(new Point(100, 100), true /* is stroked */, false /* is smooth join */);
     ctx.LineTo(new Point(100, 50), true /* is stroked */, false /* is smooth join */);
 }
 return geometry;

How can I get back the Point objects from the StreamGeometry?
I can’t seem to find any suitable method. All I can see is ToString(), which gives me the mini-language format : {M10,100L100,100 100,50z}

Answer 1

here’s what we did for a similar task. Please note, your geometries mustn’t contain nothing bar the lines. Basically it’s a tiny level of abstraction on top of Geometry, Stroke() returns a tuple with the mimilanguage and the collection of Points. You can make Navigator bindable by writing a simple behavior, please let me know if interested and I’ll adjust my answer for it.

Update 1 – the function, which accepts minilang expression and returns a Point array:

public static Point[] Parse(string minilanguage)
        {
            // leave just M's
            minilanguage = minilanguage.ToUpper().Replace("M", string.Empty);

            // remove spaces
            minilanguage = minilanguage
                .ToCharArray()
                .Where(t => t != ' ')
                .Select(t => t.ToString())
                .Aggregate((f, s) => f + s).ToString();


            return minilanguage
                .Split("L".ToCharArray())
                .Select(t => Point.Parse(t))
                .ToArray();
        }

Code:

using System;
using System.Collections.Generic;
using System.Linq;
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 GeometryParts
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            this.Loaded += new RoutedEventHandler(MainWindow_Loaded);
        }

        void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            Navigator navigator = new Navigator(0, 0);

            navigator.NavigateTo(30, 30);
            navigator.NavigateTo(60, 0);

            Tuple<string, Point[]> stroke = navigator.Stroke();
            this.g.Data = Geometry.Parse(stroke.Item1);

            MessageBox.Show(stroke.Item2.Length.ToString());
        }
    }


    public class Navigator
    {
        private List<Point> points = new List<Point>();

        public Navigator(double x, double y)
        {
            this.points.Add(new Point(x, y));
        }

        public void NavigateTo(double x, double y)
        {
            this.points.Add(new Point(x, y));
        }

        public Tuple<string, Point[]> Stroke()
        {
            string path = this.points.Select(t => t.ToString()).Aggregate((f, s) => "L" + f + " L" + s);
            path = "M" + path.Substring(2, path.Length - 2);

            Tuple<string, Point[]> stroke = new Tuple<string, Point[]>(path, this.points.ToArray());
            points.Clear();

            return stroke;
        }
    }
}

Markup:

<Window x:Class="GeometryParts.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Path Stroke="Gray" StrokeThickness="2" x:Name="g" />
    </Grid>
</Window>