Quickstart: Using brushes (XAML)

Applies to Windows and Windows Phone

Brush objects are used to paint the interiors or outlines of shapes, text, and parts of controls, so that the object being painted is visible in a UI. Let's look at the available brushes and how to use them.

Roadmap: How does this topic relate to others? See:

Introduction to brushes

To paint an object such as a Shape or the parts of a Control that is displayed on the app canvas, you use a Brush. For example, you set the Fill property of the Shape or the Background and Foreground properties of a Control to a Brush value, and that Brush determines how the UI element paints or is rendered in UI. The different types of brushes are: SolidColorBrush, LinearGradientBrush, ImageBrush, and WebViewBrush.

Solid color brushes

A SolidColorBrush paints an area with a single Color, such as red or blue. This is the most basic brush. There are three ways in XAML to define a SolidColorBrush and the solid color it specifies: predefined color names, hexadecimal color values, or the property element syntax.

Predefined color names

You can use a predefined color name, such as Yellow or Magenta. There are 256 available named colors. The XAML parser converts the color name to a Color structure with the correct color channels. The 256 named colors are based on the X11 color names from the Cascading Style Sheets, Level 3 (CSS3) specification, so you may already be familiar with this list of named colors if you have previous experience with Web development or design.

Here's an example that sets the Fill property of a Rectangle to the predefined color Red.


<StackPanel>
    <Rectangle Width="100" Height="100" Fill="Red" />
</StackPanel> 

This image shows the SolidColorBrush as applied to the Rectangle.

A rendered SolidColorBrush.

If you are defining a SolidColorBrush using code rather than XAML, each named color is available as a static property value of the Colors class. For example, to declare a Color value of a SolidColorBrush to represent the named color "Orchid", set the Color value to the static value Colors.Orchid.

Hexadecimal color values

You can use a hexadecimal format string to declare precise 24-bit color values with 8-bit alpha channel for a SolidColorBrush. Two characters in the range 0 to F define each component value, and the component value order of the hexadecimal string is: alpha channel (opacity), red channel, green channel, and blue channel. For example, the hexadecimal value "#FFFF0000" defines fully opaque red (alpha="FF", red="FF", green="00", and blue="00").

This XAML example sets the Fill property of a Rectangle to the hexadecimal value "#FFFF0000", and gives an identical result to using the named color Colors.Red.


<StackPanel>
  <Rectangle Width="100" Height="100" Fill="#FFFF0000" />
</StackPanel>

Property element syntax

You can use property element syntax to define a SolidColorBrush. This syntax is more verbose than the previous methods, but you can specify additional property values on an element, such as the Opacity. For more info on XAML syntax, including property element syntax, see XAML overview.

In the previous examples, you never even saw the string "SolidColorBrush" appear in the syntax. The brush being created is created implicitly and automatically, as part of a deliberate XAML language shorthand that helps keep UI definition simple for the most common cases. The next example creates a Rectangle and explicitly creates the SolidColorBrush as an element value for a Rectangle.Fill property. The Color of the SolidColorBrush is set to Blue and the Opacity is set to 0.5.


<Grid>
  <Rectangle Width="200" Height="150">
     <Rectangle.Fill>
        <SolidColorBrush Color="Blue" Opacity="0.5" />
     </Rectangle.Fill>
  </Rectangle>
</Grid>

Linear gradient brushes

A LinearGradientBrush paints an area with a gradient that's defined along a line. This line is called the gradient axis. You specify the gradient's colors and their locations along the gradient axis using GradientStop objects. By default, the gradient axis runs from the upper left corner to the lower right corner of the area that the brush paints, resulting in a diagonal shading.

The GradientStop is the basic building block of a gradient brush. A gradient stop specifies what the Color of the brush is at an Offset along the gradient axis, when the brush is applied to the area being painted.

The gradient stop's Color property specifies the color of the gradient stop. You can set the color by using a predefined color name or by specifying the hexadecimal ARGB values.

The Offset property of a GradientStop specifies the position of each GradientStop along the gradient axis. The Offset is a double that ranges from 0 to 1. An Offset of 0 places the GradientStop at the start of the gradient axis, in other words near its StartPoint. An Offset of 1 places the GradientStop at the EndPoint. At a minimum, a useful LinearGradientBrush should have two GradientStop values, where each GradientStop should specify a different Color and have a different Offset between 0 and 1.

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


<StackPanel>
 <!-- This rectangle is painted with a diagonal linear gradient. -->
  <Rectangle Width="200" Height="100">
    <Rectangle.Fill>
      <LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="Yellow" Offset="0.0" x:Name="GradientStop1"/>
        <GradientStop Color="Red" Offset="0.25" x:Name="GradientStop2"/>
        <GradientStop Color="Blue" Offset="0.75" x:Name="GradientStop3"/>
        <GradientStop Color="LimeGreen" Offset="1.0" x:Name="GradientStop4"/>
      </LinearGradientBrush>
    </Rectangle.Fill>
  </Rectangle>
</StackPanel>

The color of each point between gradient stops is linearly interpolated as a combination of the color specified by the two bounding gradient stops. The illustration highlights the gradient stops in the previous example. The circles mark the position of the gradient stops, and the dashed line shows the gradient axis.

Gradient stops

You can change the line at which the gradient stops are positioned by setting the StartPoint and EndPoint properties to be different values than the (0,0) and (1,1) starting defaults. By changing the StartPoint and EndPoint coordinate values, you can create horizontal or vertical gradients, reverse the gradient direction, or condense the gradient spread to apply to a smaller range than the full painted area. To condense the gradient, you set values of StartPoint and/or EndPoint to be something that is between the values 0 and 1. For example, if you want a horizontal gradient where the fade all happens on the left half of the brush and the right side is solid to your last GradientStop color, you specify a StartPoint of (0,0) and an EndPoint of (0.5,0).

Image brushes

An ImageBrush paints an area with an image, with the image to paint coming from an image file source. You set the ImageSource property with the path of the image to load. Typically, the image source comes from a Content item that is part of your app's resources.

By default, an ImageBrush stretches its image to completely fill the painted area, possibly distorting the image if the painted area has a different aspect ratio than the image. You can change this behavior by changing the Stretch property from its default value of Fill and setting it as None, Uniform, or UniformToFill.

The next example creates an ImageBrush and sets the ImageSource to an image named licorice.jpg, which you must include as a resource in the app. The ImageBrush then paints the area defined by an Ellipse shape.


<Ellipse Height="200" Width="300">
   <Ellipse.Fill>
     <ImageBrush ImageSource="licorice.jpg" />
   </Ellipse.Fill>
</Ellipse>

Here's what the rendered ImageBrush looks like.

A rendered ImageBrush.

ImageBrush and Image both reference an image source file by Uniform Resource Identifier (URI), where that image source file uses several possible image formats. These image source files are specified as URIs. For more info about specifying image sources, the usable image formats, and packaging them in an app, see Quickstart: Image and ImageBrush.

Brushes and text

You can also use brushes to apply rendering characteristics to text elements. For example, the Foreground property of TextBlock takes a Brush. You can apply any of the brushes described here to text. But be careful with brushes applied to text, because it's possible to make the text unreadable if you use brushes that bleed into whatever background the text is rendered on top of, or that distract from the outlines of text characters. Use SolidColorBrush for readability of text elements in most cases, unless you want the text element to be mostly decorative.

Even when you use a solid color, make sure that the text color you choose has enough contrast against the background color of the text's layout container. The level of contrast between text foreground and text container background is an accessibility consideration.

WebViewBrush

A WebViewBrush is a special type of brush that can access the content normally viewed in a WebView control. Instead of rendering the content in the rectangular WebView control area, WebViewBrush paints that content onto another element that has a Brush-type property for a render surface. WebViewBrush isn't appropriate for every brush scenario, but is useful for transitions of a WebView. For more info, see WebViewBrush.

Brushes as XAML resources

You can declare any brush to be a keyed XAML resource in a XAML resource dictionary. This makes it easy to replicate the same brush values as applied to multiple elements in a UI. The brush values are then shared and applied to any case where you reference the brush resource as a {StaticResource} usage in your XAML. This includes cases where you have a XAML control template that references the shared brush, and the control template is itself a keyed XAML resource.

Brushes in code

It's much more typical to specify brushes using XAML than it is to use code to define brushes. This is because brushes are usually defined as XAML resources, and because brush values are often the output of design tools or otherwise as part of a XAML UI definition. Still, for the occasional case where you might want to define a brush using code, all the Brush types are available for code instantiation.

To create a SolidColorBrush in code, use the constructor that takes a Color parameter. Pass a value that is a static property of the Colors class, like this:


blueBrush = ref new SolidColorBrush(Windows::UI::Colors::Blue);

For WebViewBrush and ImageBrush, use the default constructor and then call other APIs before you attempt to use that brush for a UI property.

  • ImageSource requires a BitmapImage (not a URI) when you define an ImageBrush using code. If your source is a stream , use the SetSourceAsync method to initialize the value. If your source is a URI, which includes content in your app that uses the ms-appx or ms-resource schemes, use the BitmapImage constructor that takes a URI. You might also consider handling the ImageOpened event if there are any timing issues with retrieving or decoding the image source, where you might need alternate content to display until the image source is available.
  • For WebViewBrush you might need to call Redraw if you've recently reset the SourceName property or if the content of the WebView is also being changed with code.
For code examples, see reference pages for WebViewBrush and ImageBrush.

Brushes samples

For more examples of using graphics and brushes in apps, see:

Related topics

Roadmap for Windows Runtime apps using C# or Visual Basic
Roadmap for Windows Runtime apps using C++
Quickstart: Drawing shapes

 

 

Show:
© 2014 Microsoft