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Jak utworzyć kształt używając StreamGeometry

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StreamGeometry jest uproszczoną alternatywą PathGeometry dla tworzenia kształtów geometrycznych. Użyj elementu StreamGeometry , jeśli musisz opisać złożoną geometrię, ale nie chcesz narzutować obsługi powiązania danych, animacji ani modyfikacji. Na przykład ze względu na jego wydajność StreamGeometry klasa jest dobrym wyborem do opisywania modułów adorujących.

Tworzenie trójkątnego strumieniaGeometry

W poniższym przykładzie użyto składni atrybutów do utworzenia trójkątnego StreamGeometry kodu XAML.

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <StackPanel>
  
    <Path Data="F0 M10,100 L100,100 100,50Z" 
      StrokeThickness="1" Stroke="Black"/>

  </StackPanel>
</Page>

Aby uzyskać więcej informacji na temat StreamGeometry składni atrybutów, zobacz stronę Składnia znaczników ścieżki .

Definiowanie trójkąta za pomocą elementu StreamGeometry

W następnym przykładzie użyto metody a StreamGeometry do zdefiniowania trójkąta w kodzie. Najpierw przykład tworzy element StreamGeometry, a następnie uzyskuje StreamGeometryContext element i używa go do opisania trójkąta.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Shapes;

namespace SDKSample
{
    // Use StreamGeometry with StreamGeometryContext to define a triangle shape.
    public partial class StreamGeometryTriangleExample : Page
    {
        public StreamGeometryTriangleExample()
        {
            // Create a path to draw a geometry with.
            Path myPath = new Path();
            myPath.Stroke = Brushes.Black;
            myPath.StrokeThickness = 1;

            // Create a StreamGeometry to use to specify myPath.
            StreamGeometry geometry = new StreamGeometry();
            geometry.FillRule = FillRule.EvenOdd;

            // Open a StreamGeometryContext that can be used to describe this StreamGeometry
            // object's contents.
            using (StreamGeometryContext ctx = geometry.Open())
            {

                // Begin the triangle at the point specified. Notice that the shape is set to
                // be closed so only two lines need to be specified below to make the triangle.
                ctx.BeginFigure(new Point(10, 100), true /* is filled */, true /* is closed */);

                // Draw a line to the next specified point.
                ctx.LineTo(new Point(100, 100), true /* is stroked */, false /* is smooth join */);

                // Draw another line to the next specified point.
                ctx.LineTo(new Point(100, 50), true /* is stroked */, false /* is smooth join */);
            }

            // Freeze the geometry (make it unmodifiable)
            // for additional performance benefits.
            geometry.Freeze();

            // Specify the shape (triangle) of the Path using the StreamGeometry.
            myPath.Data = geometry;

            // Add path shape to the UI.
            StackPanel mainPanel = new StackPanel();
            mainPanel.Children.Add(myPath);
            this.Content = mainPanel;
        }
    }
}


Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.Windows.Shapes

Namespace SDKSample
    ' Use StreamGeometry with StreamGeometryContext to define a triangle shape.
    Partial Public Class StreamGeometryTriangleExample
        Inherits Page
        Public Sub New()
            ' Create a path to draw a geometry with.
            Dim myPath As New Path()
            myPath.Stroke = Brushes.Black
            myPath.StrokeThickness = 1

            ' Create a StreamGeometry to use to specify myPath.
            Dim geometry As New StreamGeometry()
            geometry.FillRule = FillRule.EvenOdd

            ' Open a StreamGeometryContext that can be used to describe this StreamGeometry 
            ' object's contents.
            Using ctx As StreamGeometryContext = geometry.Open()

                ' Begin the triangle at the point specified. Notice that the shape is set to 
                ' be closed so only two lines need to be specified below to make the triangle.
                ctx.BeginFigure(New Point(10, 100), True, True) ' is closed  -  is filled 

                ' Draw a line to the next specified point.
                ctx.LineTo(New Point(100, 100), True, False) ' is smooth join  -  is stroked 

                ' Draw another line to the next specified point.
                ctx.LineTo(New Point(100, 50), True, False) ' is smooth join  -  is stroked 
            End Using

            ' Freeze the geometry (make it unmodifiable)
            ' for additional performance benefits.
            geometry.Freeze()

            ' Specify the shape (triangle) of the Path using the StreamGeometry.
            myPath.Data = geometry

            ' Add path shape to the UI.
            Dim mainPanel As New StackPanel()
            mainPanel.Children.Add(myPath)
            Me.Content = mainPanel
        End Sub
    End Class
End Namespace

Tworzenie kształtu geometrycznego w kodzie

W następnym przykładzie zostanie utworzona metoda, która używa StreamGeometry elementu i StreamGeometryContext do definiowania kształtu geometrycznego na podstawie określonych parametrów.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Shapes;

namespace SDKSample
{
    public partial class StreamGeometryExample : Page
    {
        public StreamGeometryExample()
        {
            // Create a path to draw a geometry with.
            Path myPath = new Path();
            myPath.Stroke = Brushes.Black;
            myPath.StrokeThickness = 1;

            // Create a StreamGeometry to use to specify myPath.
            StreamGeometry theGeometry = BuildRegularPolygon(new Point(200, 200), 200, 8, 0);
            theGeometry.FillRule = FillRule.EvenOdd;

            // Freeze the geometry (make it unmodifiable)
            // for additional performance benefits.
            theGeometry.Freeze();

            // Use the StreamGeometry returned by the BuildRegularPolygon to
            // specify the shape of the path.
            myPath.Data = theGeometry;

            // Add path shape to the UI.
            StackPanel mainPanel = new StackPanel();
            mainPanel.Children.Add(myPath);
            this.Content = mainPanel;
        }

        StreamGeometry BuildRegularPolygon(Point c, double r, int numSides, double offsetDegree)
        {
            // c is the center, r is the radius,
            // numSides the number of sides, offsetDegree the offset in Degrees.
            // Do not add the last point.

            StreamGeometry geometry = new StreamGeometry();

            using (StreamGeometryContext ctx = geometry.Open())
            {
                ctx.BeginFigure(new Point(), true /* is filled */, true /* is closed */);

                double step = 2 * Math.PI / Math.Max(numSides, 3);
                Point cur = c;

                double a = Math.PI * offsetDegree / 180.0;
                for (int i = 0; i < numSides; i++, a += step)
                {
                    cur.X = c.X + r * Math.Cos(a);
                    cur.Y = c.Y + r * Math.Sin(a);
                    ctx.LineTo(cur, true /* is stroked */, false /* is smooth join */);
                }
            }

            return geometry;
        }
    }
}


Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.Windows.Shapes

Namespace SDKSample
    Partial Public Class StreamGeometryExample
        Inherits Page
        Public Sub New()
            ' Create a path to draw a geometry with.
            Dim myPath As New Path()
            myPath.Stroke = Brushes.Black
            myPath.StrokeThickness = 1

            ' Create a StreamGeometry to use to specify myPath.
            Dim theGeometry As StreamGeometry = BuildRegularPolygon(New Point(200, 200), 200, 8, 0)
            theGeometry.FillRule = FillRule.EvenOdd

            ' Freeze the geometry (make it unmodifiable)
            ' for additional performance benefits.
            theGeometry.Freeze()

            ' Use the StreamGeometry returned by the BuildRegularPolygon to 
            ' specify the shape of the path.
            myPath.Data = theGeometry

            ' Add path shape to the UI.
            Dim mainPanel As New StackPanel()
            mainPanel.Children.Add(myPath)
            Me.Content = mainPanel
        End Sub

        Private Function BuildRegularPolygon(ByVal c As Point, ByVal r As Double, ByVal numSides As Integer, ByVal offsetDegree As Double) As StreamGeometry
            ' c is the center, r is the radius,
            ' numSides the number of sides, offsetDegree the offset in Degrees.
            ' Do not add the last point.

            Dim geometry As New StreamGeometry()

            Using ctx As StreamGeometryContext = geometry.Open()
                ctx.BeginFigure(New Point(), True, True) ' is closed  -  is filled 

                Dim [step] As Double = 2 * Math.PI / Math.Max(numSides, 3)
                Dim cur As Point = c

                Dim a As Double = Math.PI * offsetDegree / 180.0
                Dim i As Integer = 0
                Do While i < numSides
                    cur.X = c.X + r * Math.Cos(a)
                    cur.Y = c.Y + r * Math.Sin(a)
                    ctx.LineTo(cur, True, False) ' is smooth join  -  is stroked 
                    i += 1
                    a += [step]
                Loop
            End Using

            Return geometry
        End Function
    End Class
End Namespace

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