Windows.UI.Xaml.Media.LinearGradientBrush

-description

Paints an area with a linear gradient.

-xaml-syntax

<LinearGradientBrush ...>
  oneOrMoreGradientStops
</LinearGradientBrush

-remarks

LinearGradientBrush is a type of Brush that is used for many possible UI properties that use a Brush to fill some or all of an object's visual area in app UI. Examples of some of the most commonly-used properties that use a Brush value include: Control.Background, Control.Foreground, Shape.Fill, Control.BorderBrush, Panel.Background, TextBlock.Foreground. LinearGradientBrush is an alternative to the more commonly used SolidColorBrush type.

The StartPoint and EndPoint properties of LinearGradientBrush describe two points in a relative coordinate space. This creates an orientation for the gradient, and typically this specifies a horizontal gradient, or a vertical gradient. A diagonal gradient can also be used. A LinearGradientBrush typically has two or more GradientStop values for the GradientStops property (an ordered collection). Each GradientStop specifies a Color and an Offset. Offset represents a position between 0 (the StartPoint) and 1 (the EndPoint) along the gradient, and the actual pixel length of the brush and its gradient are adjusted based on the UI where you apply your LinearGradientBrush as a value. For more info on how Offset values are defined and how Offset, StartPoint and EndPoint are related, see Use brushes. It's common to use

You can use the Transparent value for one of the GradientStop colors. Although this doesn't visually apply any changes to UI (it's transparent), that point is detectable for hit-testing purposes. For more info on hit testing, see "Hit testing" section of Mouse interactions.

The GradientStop values of a LinearGradientBrush can be animated as part of transitions or decorative animations. Use one of the dedicated animation types that can animate a Color value. This usually involves having .(GradientStop.Color) be a part of a longer property path for a Storyboard.TargetProperty value. For more info on property targeting and how to animate properties that use Brush values, see Storyboarded animations.

Brushes as XAML resources

Each of the Brush types that can be declared in XAML (SolidColorBrush, LinearGradientBrush, ImageBrush) is intended to be defined as a resource, so that you can reuse that brush as a resource throughout your app. The XAML syntax shown for Brush types is appropriate for defining the brush as a resource. When you declare a brush as a resource, you also need an x:Key attribute that you'll later use to refer to that resource from other UI definitions. For more info on XAML resources and how to use x:Key attribute, see ResourceDictionary and XAML resource references.

The advantage of declaring brushes as resources is that it reduces the number of runtime objects that are needed to construct a UI: the brush is now shared as a common resource that's providing values for multiple parts of the object graph.

If you look at the existing control template definitions for Windows Runtime XAML controls, you'll see that the templates use brush resources extensively (although these are usually SolidColorBrush, not LinearGradientBrush). Many of these resources are system resources, and they use the {ThemeResource} markup extension for the resource reference rather than {StaticResource} markup extension. For more info on how to use system resource brushes in your own control template XAML, see XAML theme resources.

-examples

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

[!code-xamlGradient3]

-see-also

GradientBrush, RadialGradientBrush, SolidColorBrush, Use brushes, ResourceDictionary and XAML resource references