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How to Create a Linear Gradient Brush

To create a linear gradient brush, use the CreateLinearGradientBrush method and specify the linear gradient brush properties and the gradient stop collection. Some overloads enable you to specify the brush properties. The following code shows how to create a linear gradient brush to fill a circle, and a solid black brush to draw the outline of the circle.

The code produces the output shown in the following illustration.

Illustration of a square filled with a linear gradient brush

  1. Declare a variable of type ID2D1LinearGradientBrush.
    
    
        ID2D1LinearGradientBrush *m_pLinearGradientBrush;
    
    
    
  2. Use the ID2D1RenderTarget::CreateGradientStopCollection method to create the ID2D1GradientStopCollection collection with a declared array of D2D1_GRADIENT_STOP structures, as shown in the following code.

    Note  Starting with Windows 8, you can use the ID2D1DeviceContext::CreateGradientStopCollection method to create a ID2D1GradientStopCollection1 collection instead. This interface adds high-color gradients and the interpolation of gradients in either straight or prmultiplied colors. See the ID2DDeviceContext::CreateGradientStopCollection page for more information.

    
    // Create an array of gradient stops to put in the gradient stop
    // collection that will be used in the gradient brush.
    ID2D1GradientStopCollection *pGradientStops = NULL;
    
    D2D1_GRADIENT_STOP gradientStops[2];
    gradientStops[0].color = D2D1::ColorF(D2D1::ColorF::Yellow, 1);
    gradientStops[0].position = 0.0f;
    gradientStops[1].color = D2D1::ColorF(D2D1::ColorF::ForestGreen, 1);
    gradientStops[1].position = 1.0f;
    // Create the ID2D1GradientStopCollection from a previously
    // declared array of D2D1_GRADIENT_STOP structs.
    hr = m_pRenderTarget->CreateGradientStopCollection(
        gradientStops,
        2,
        D2D1_GAMMA_2_2,
        D2D1_EXTEND_MODE_CLAMP,
        &pGradientStops
        );
    
    
    
  3. Use the ID2D1RenderTarget::CreateLinearGradientBrush to create a linear gradient brush, fill the square with the brush, and draw the square with the black color brush.
    
    // The line that determines the direction of the gradient starts at
    // the upper-left corner of the square and ends at the lower-right corner.
    
    if (SUCCEEDED(hr))
    {
        hr = m_pRenderTarget->CreateLinearGradientBrush(
            D2D1::LinearGradientBrushProperties(
                D2D1::Point2F(0, 0),
                D2D1::Point2F(150, 150)),
            pGradientStops,
            &m_pLinearGradientBrush
            );
    }
    
    
    
    
    m_pRenderTarget->FillRectangle(&rcBrushRect, m_pLinearGradientBrush);
    m_pRenderTarget->DrawRectangle(&rcBrushRect, m_pBlackBrush, 1, NULL);
    
    
    

For a complete example, see Brush Types Example.

Related topics

Direct2D Reference

 

 

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