Path Markup Syntax

This topic describes the Extensible Application Markup Language (XAML) usage syntax for describing paths. WPF supports a powerful and complex mini-language that you can use to describe geometric paths.

This topic contains the following sections.

• Prerequisites
• StreamGeometry and PathFigureCollection Mini-Languages
• Move Command
• Draw Commands
• The Close Command
• Point Syntax
• Special Values
• Related Topics

Prerequisites

To understand this topic, you should be familiar with the basic features of Geometry objects. For more information, see the Geometry Overview.

StreamGeometry and PathFigureCollection Mini-Languages

WPF provides two classes that provide mini-languages for describing geometric paths: StreamGeometry and PathFigureCollection.

• You use the StreamGeometry mini-language when setting a property of type Geometry, such as the Clip property of a UIElement or the Data property of a Path element. The following example uses attribute syntax to create a StreamGeometry.

  <Path Stroke="Black" Fill="Gray"
        Data="M 10,100 C 10,300 300,-200 300,100" />
  

• You use the PathFigureCollection mini-language when setting the Figures property of a PathGeometry. The following example uses a attribute syntax to create a PathFigureCollection for a PathGeometry.

  <Path Stroke="Black" Fill="Gray">
    <Path.Data>
      <PathGeometry Figures="M 10,100 C 10,300 300,-200 300,100" />
    </Path.Data>
  </Path>
  

As you can see from the preceding examples, the two mini-languages are very similar. It's always possible to use a PathGeometry in any situation where you could use a StreamGeometry; so which one should you use? Use a StreamGeometry when you don't need to modify the path after creating it; use a PathGeometry if you do need to modify the path.

For more information about the differences between PathGeometry and StreamGeometry objects, see the Geometry Overview.

A Note about White Space

For brevity, a single space is shown in the syntax sections that follow, but multiple spaces are also acceptable wherever a single space is shown.

Two numbers don’t actually have to be separated by a comma or whitespace, but this can only be done when the resulting string is unambiguous. For instance, 2..3 is actually two numbers: “2.” And “.3”. Similarly, 2-3 is “2” and “-3”. Spaces are not required before or after commands, either.

Syntax

The Extensible Application Markup Language (XAML) attribute usage syntax for a StreamGeometry is composed of an optional FillRule value and one or more figure descriptions.

The Extensible Application Markup Language (XAML) attribute usage syntax for a PathFigureCollection is composed of one or more figure descriptions.

Move Command

Specifies the start point of a new figure.

An uppercase M indicates that startPoint is an absolute value; a lowercase m indicates that startPoint is an offset to the previous point, or (0,0) if none exists. If you list multiple points after the move command, a line is drawn to those points though you specified the line command.

Draw Commands

A draw command can consist of several shape commands. The following shape commands are available: line, horizontal line, vertical line, cubic Bezier curve, quadratic Bezier curve, smooth cubic Bezier curve, smooth quadratic Bezier curve, and elliptical arc.

You enter each command by using either an uppercase or a lowercase letter: uppercase letters denote absolute values and lowercase letters denote relative values: the control points for that segment are relative to the end point of the preceding example. When sequentially entering more than one command of the same type, you can omit the duplicate command entry; for example, L 100,200 300,400 is equivalent to L 100,200 L 300,400. The following table describes the move and draw commands.

Line Command

Creates a straight line between the current point and the specified end point. l 20 30 and L 20,30 are examples of valid line commands.

Horizontal Line Command

Creates a horizontal line between the current point and the specified x-coordinate. H 90 is an example of a valid horizontal line command.

Vertical Line Command

Creates a vertical line between the current point and the specified y-coordinate. v 90 is an example of a valid vertical line command.

Cubic Bezier Curve Command

Creates a cubic Bezier curve between the current point and the specified end point by using the two specified control points (controlPoint₁ and controlPoint₂). C 100,200 200,400 300,200 is an example of a valid curve command.

Quadratic Bezier Curve Command

Creates a quadratic Bezier curve between the current point and the specified end point by using the specified control point (controlPoint). q 100,200 300,200 is an example of a valid quadratic Bezier curve command.

Smooth cubic Bezier curve Command

Creates a cubic Bezier curve between the current point and the specified end point. The first control point is assumed to be the reflection of the second control point of the previous command relative to the current point. If there is no previous command or if the previous command was not a cubic Bezier curve command or a smooth cubic Bezier curve command, assume the first control point is coincident with the current point. The second control point, the control point for the end of the curve, is specified by controlPoint₂. For example, S 100,200 200,300 is a valid smooth cubic Bezier curve command.

Smooth cubic Bezier curve Command

Creates a quadratic Bezier curve between the current point and the specified end point. The control point is assumed to be the reflection of the control point of the previous command relative to the current point. If there is no previous command or if the previous command was not a quadratic Bezier curve command or a smooth quadratic Bezier curve command, the control point is coincident with the current point.

Elliptical Arc Command

Creates an elliptical arc between the current point and the specified end point.

The Close Command

Ends the current figure and creates a line that connects the current point to the starting point of the figure. This command creates a line-join (corner) between the last segment and the first segment of the figure.

Point Syntax

Describes the x- and y-coordinates of a point.

Special Values

Instead of a standard numerical value, you can also use the following special values. These values are case-sensitive.

• Ininity
  Represents System.Double.PositiveInfinity.

• -Infinity
  Represents System.Double.NegativeInfinity.

• NaN
  Represents System.Double.NaN.

You may also use scientific notation. For example, +1.e17 is a valid value.

See Also

Reference

StreamGeometry
PathGeometry
PathFigureCollection

Concepts

Geometry Overview

Other Resources

Geometries How-to Topics