Como: Pintar uma Área com um Gradiente Linear

This example shows how to use the LinearGradientBrush class to paint an area with a linear gradient. In the following example, the Fill of a Rectangle is painted with a diagonal linear gradient that transitions from yellow to red to blue to lime green.

Exemplo

<!-- 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" />
      <GradientStop Color="Red" Offset="0.25" />
      <GradientStop Color="Blue" Offset="0.75" />
      <GradientStop Color="LimeGreen" Offset="1.0" />
    </LinearGradientBrush>
  </Rectangle.Fill>
</Rectangle>

Rectangle diagonalFillRectangle = new Rectangle();
diagonalFillRectangle.Width = 200;
diagonalFillRectangle.Height = 100;

// Create a diagonal linear gradient with four stops.   
LinearGradientBrush myLinearGradientBrush =
    new LinearGradientBrush();
myLinearGradientBrush.StartPoint = new Point(0,0);
myLinearGradientBrush.EndPoint = new Point(1,1);
myLinearGradientBrush.GradientStops.Add(
    new GradientStop(Colors.Yellow, 0.0));
myLinearGradientBrush.GradientStops.Add(
    new GradientStop(Colors.Red, 0.25));                
myLinearGradientBrush.GradientStops.Add(
    new GradientStop(Colors.Blue, 0.75));        
myLinearGradientBrush.GradientStops.Add(
    new GradientStop(Colors.LimeGreen, 1.0));

// Use the brush to paint the rectangle.
diagonalFillRectangle.Fill = myLinearGradientBrush;

The following illustration shows the gradient created by the previous example.

To create a horizontal linear gradient, change the StartPoint and EndPoint of the LinearGradientBrush to (0,0.5) and (1,0.5). In the following example, a Rectangle is painted with a horizontal linear gradient.

<!-- This rectangle is painted with a horizontal linear gradient. -->
<Rectangle Width="200" Height="100">
  <Rectangle.Fill>
    <LinearGradientBrush StartPoint="0,0.5" EndPoint="1,0.5">
      <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>

            Rectangle horizontalFillRectangle = new Rectangle();
            horizontalFillRectangle.Width = 200;
            horizontalFillRectangle.Height = 100;

            // Create a horizontal linear gradient with four stops.   
            LinearGradientBrush myHorizontalGradient =
                new LinearGradientBrush();
            myHorizontalGradient.StartPoint = new Point(0,0.5);
            myHorizontalGradient.EndPoint = new Point(1,0.5);
            myHorizontalGradient.GradientStops.Add(
                new GradientStop(Colors.Yellow, 0.0));
            myHorizontalGradient.GradientStops.Add(
                new GradientStop(Colors.Red, 0.25));                
            myHorizontalGradient.GradientStops.Add(
                new GradientStop(Colors.Blue, 0.75));        
            myHorizontalGradient.GradientStops.Add(
                new GradientStop(Colors.LimeGreen, 1.0));

            // Use the brush to paint the rectangle.
            horizontalFillRectangle.Fill = myHorizontalGradient; 

The following illustration shows the gradient created by the previous example.

To create a vertical linear gradient, change the StartPoint and EndPoint of the LinearGradientBrush to (0.5,0) and (0.5,1). In the following example, a Rectangle is painted with a vertical linear gradient.

<!-- This rectangle is painted with a vertical 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>

Rectangle verticalFillRectangle = new Rectangle();
verticalFillRectangle.Width = 200;
verticalFillRectangle.Height = 100;

// Create a vertical linear gradient with four stops.   
LinearGradientBrush myVerticalGradient =
    new LinearGradientBrush();
myVerticalGradient.StartPoint = new Point(0.5,0);
myVerticalGradient.EndPoint = new Point(0.5,1);
myVerticalGradient.GradientStops.Add(
    new GradientStop(Colors.Yellow, 0.0));
myVerticalGradient.GradientStops.Add(
    new GradientStop(Colors.Red, 0.25));                
myVerticalGradient.GradientStops.Add(
    new GradientStop(Colors.Blue, 0.75));        
myVerticalGradient.GradientStops.Add(
    new GradientStop(Colors.LimeGreen, 1.0));

// Use the brush to paint the rectangle.
verticalFillRectangle.Fill = myVerticalGradient;  

The following illustration shows the gradient created by the previous example.

Observação

The examples in this topic use the default coordinate system for setting start points and end points.O sistema de coordenadas padrão é em relação a uma caixa delimitadora: 0 indica 0 por cento da caixa delimitadora, e 1 indica a 100 por cento da caixa delimitadora.You can change this coordinate system by setting the MappingMode property to the value BrushMappingMode.Absolute.An absolute coordinate system is not relative to a bounding box.Values are interpreted directly in local space.

Para obter exemplos adicionais, consulte A amostra de pincéis. For more information about gradients and other types of brushes, see Painting with Solid Colors and Gradients Overview.