CombinedGeometry Class

The GeometryCombineMode property specifies how the two geometries will be combined. Note that CombinedGeometry combines the area specified by two geometries, so geometries that do not have area (such as LineGeometry) disappear when combined.

Geometries can be combined in several ways: using a GeometryGroup, a CombinedGeometry, or the Combine method of the Geometry class.

• A GeometryGroup creates a composite geometry from one or more Geometry objects.

• A CombinedGeometry uses a specified boolean operation to combine the area described by two Geometry objects.

• The static Combine method of the Geometry class behaves in exactly the same manner as the CombinedGeometry object.

Careful thought should be involved when using a CombinedGeometry to perform a union as it can be very CPU-expensive. In most cases, a GeometryGroup or AddGeometry will work better.

Use a CombinedGeometry only when any of the following apply:

• The geometric operation is not a union.

• Either of the geometries have a FillRule value of EvenOdd and the geometries are self-intersecting (i.e. the FillRule actually matters).

• Time is not a concern, but space is (for instance, if the geometry is created once and then cached). Typically, CombinedGeometry produces smaller output than AddGeometry.

• The resulting geometry will be stroked or used in a path animation and AddGeometry does not provide the desired outline.

Freezable Features

This example shows how to combine geometries. To combine two geometries, use a CombinedGeometry object. Set its Geometry1 and Geometry2 properties with the two geometries to combine, and set the GeometryCombineMode property, which determines how the geometries will be combined together, to Union, Intersect, Exclude, or Xor.

To create a composite geometry from two or more geometries, use a GeometryGroup.

In the following example, a CombinedGeometry is defined with a geometry combine mode of Exclude. Both Geometry1 and the Geometry2 are defined as circles of the same radius, but with centers offset by 50.

<Path Stroke="Black" StrokeThickness="1" Fill="#CCCCFF">
  <Path.Data>

    <!-- Combines two geometries using the exclude combine mode. -->
    <CombinedGeometry GeometryCombineMode="Exclude">
      <CombinedGeometry.Geometry1>
        <EllipseGeometry RadiusX="50" RadiusY="50" Center="75,75" />
      </CombinedGeometry.Geometry1>
      <CombinedGeometry.Geometry2>
        <EllipseGeometry RadiusX="50" RadiusY="50" Center="125,75" />
      </CombinedGeometry.Geometry2>
    </CombinedGeometry>
  </Path.Data>
</Path>

In the following markup, a CombinedGeometry is defined with a combine mode of Intersect. Both Geometry1 and the Geometry2 are defined as circles of the same radius, but with centers offset by 50.

<Path Stroke="Black" StrokeThickness="1" Fill="#CCCCFF">
  <Path.Data>

    <!-- Combines two geometries using the intersect combine mode. -->
    <CombinedGeometry GeometryCombineMode="Intersect">
      <CombinedGeometry.Geometry1>
        <EllipseGeometry RadiusX="50" RadiusY="50" Center="75,75" />
      </CombinedGeometry.Geometry1>
      <CombinedGeometry.Geometry2>
        <EllipseGeometry RadiusX="50" RadiusY="50" Center="125,75" />
      </CombinedGeometry.Geometry2>
    </CombinedGeometry>
  </Path.Data>
</Path>

In the following markup, a CombinedGeometry is defined with a combine mode of Union. Both Geometry1 and the Geometry2 are defined as circles of the same radius, but with centers offset by 50.

<Path Stroke="Black" StrokeThickness="1" Fill="#CCCCFF">
  <Path.Data>

    <!-- Combines two geometries using the union combine mode. -->
    <CombinedGeometry GeometryCombineMode="Union">
      <CombinedGeometry.Geometry1>
        <EllipseGeometry RadiusX="50" RadiusY="50" Center="75,75" />
      </CombinedGeometry.Geometry1>
      <CombinedGeometry.Geometry2>
        <EllipseGeometry RadiusX="50" RadiusY="50" Center="125,75" />
      </CombinedGeometry.Geometry2>
    </CombinedGeometry>
  </Path.Data>
</Path>

In the following markup, a CombinedGeometry is defined with a combine mode of Xor. Both Geometry1 and the Geometry2 are defined as circles of the same radius, but with centers offset by 50.

<Path Stroke="Black" StrokeThickness="1" Fill="#CCCCFF">
  <Path.Data>

    <!-- Combines two geometries using the XOR combine mode. -->
    <CombinedGeometry GeometryCombineMode="Xor">
      <CombinedGeometry.Geometry1>
        <EllipseGeometry RadiusX="50" RadiusY="50" Center="75,75" />
      </CombinedGeometry.Geometry1>
      <CombinedGeometry.Geometry2>
        <EllipseGeometry RadiusX="50" RadiusY="50" Center="125,75" />
      </CombinedGeometry.Geometry2>
    </CombinedGeometry>
  </Path.Data>
</Path>

.NET Framework

.NET Framework Client Profile

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

Other Resources