Articolo
11/18/2011

LinearGradientBrush Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Paints an area with a linear gradient.

Inheritance Hierarchy

System.Object
  System.Windows.DependencyObject
    System.Windows.Media.Brush
      System.Windows.Media.GradientBrush
        System.Windows.Media.LinearGradientBrush

Namespace: System.Windows.Media
Assembly: System.Windows (in System.Windows.dll)

Syntax

'Declaration
Public NotInheritable Class LinearGradientBrush _
    Inherits GradientBrush

public sealed class LinearGradientBrush : GradientBrush

<LinearGradientBrush ...>
  oneOrMoreGradientStops
</LinearGradientBrush

XAML Values

oneOrMoreGradientStops
One or more GradientStop object elements. Object elements defined here become members of the GradientStopCollection when code accesses the GradientStops property at run time.

The LinearGradientBrush type exposes the following members.

Constructors

	Name	Description
	LinearGradientBrush()	Initializes a new instance of the LinearGradientBrush class.
	LinearGradientBrush(GradientStopCollection, Double)	Initializes a new instance of the LinearGradientBrush class that has the specified GradientStopCollection and angle.

Top

Properties

	Name	Description
	ColorInterpolationMode	Gets or sets a ColorInterpolationMode enumeration value that specifies how the gradient's colors are interpolated. (Inherited from GradientBrush.)
	Dispatcher	Gets the Dispatcher this object is associated with. (Inherited from DependencyObject.)
	EndPoint	Gets or sets the ending two-dimensional coordinates of the linear gradient.
	GradientStops	Gets or sets the brush's gradient stops. (Inherited from GradientBrush.)
	MappingMode	Gets or sets a BrushMappingMode enumeration value that specifies whether the positioning coordinates of the gradient brush are absolute or relative to the output area. (Inherited from GradientBrush.)
	Opacity	Gets or sets the degree of opacity of a Brush. (Inherited from Brush.)
	RelativeTransform	Gets or sets the transformation that is applied to the brush using relative coordinates. (Inherited from Brush.)
	SpreadMethod	Gets or sets the type of spread method that specifies how to draw a gradient that starts or ends inside the bounds of the object to be painted. (Inherited from GradientBrush.)
	StartPoint	Gets or sets the starting two-dimensional coordinates of the linear gradient.
	Transform	Gets or sets the transformation that is applied to the brush. (Inherited from Brush.)

Top

Methods

	Name	Description
	CheckAccess	Determines whether the calling thread has access to this object. (Inherited from DependencyObject.)
	ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject.)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetAnimationBaseValue	Returns any base value established for a Silverlight dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetValue	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
	SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

Top

Fields

	Name	Description
	EndPointProperty	Identifies the EndPoint dependency property.
	StartPointProperty	Identifies the StartPoint dependency property.

Top

Remarks

A LinearGradientBrush paints an area with a linear gradient. A linear gradient defines a gradient along a line. The line's end points are defined by the StartPoint and EndPoint properties of the linear gradient. A LinearGradientBrush brush paints its GradientStops along this line.

The default linear gradient is diagonal. In the default, the StartPoint of a linear gradient is a Point with value 0,0, the upper-left corner of the area being painted, and its EndPoint is a Point with value 1,1, the lower-right corner of the area being painted. The colors in the resulting gradient are interpolated along the diagonal path.

The following illustration shows a diagonal gradient. A line was added to highlight the interpolation path of the gradient from the start point to the end point.

A diagonal linear gradient

Shows a gradient axis.

The next illustration shows the same linear gradient, but with highlighted gradient stops.

A diagonal linear gradient with highlighted gradient stops

Gradient with gradient stops.

It is possible to specify a gradient axis that does not completely fill area being painted. When this occurs, the SpreadMethod property determines how the remaining area is painted.

Examples

The following example creates a linear gradient with four colors and uses it to paint a Rectangle.

<StackPanel>
  <!-- This rectangle is painted with a vertical linear gradient. -->
  <Rectangle Width="200" Height="100">
    <Rectangle.Fill>
      <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
        <GradientStop Color="Yellow" Offset="0.0" />
        <GradientStop Color="Red" Offset="0.25" />
        <GradientStop Color="Blue" Offset="0.75" />
        <GradientStop Color="LimeGreen" Offset="1.0" />
      </LinearGradientBrush>
    </Rectangle.Fill>
  </Rectangle>
</StackPanel>

The following illustration shows the resulting gradient. The gradient axis is marked with a dashed line, and the gradient stops are marked with circles.

Gradient axis for a vertical gradient

Gradient Stops of Linear Gradient

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Condividi tramite