D2D1_GRADIENT_STOP structure (d2d1.h)

Contains the position and color of a gradient stop.

Syntax

typedef struct D2D1_GRADIENT_STOP {
  FLOAT        position;
  D2D1_COLOR_F color;
} D2D1_GRADIENT_STOP;

Members

position

Type: FLOAT

A value that indicates the relative position of the gradient stop in the brush. This value must be in the [0.0f, 1.0f] range if the gradient stop is to be seen explicitly.

color

Type: D2D1_COLOR_F

The color of the gradient stop.

Remarks

Gradient stops can be specified in any order if they are at different positions. Two stops may share a position. In this case, the first stop specified is treated as the "low" stop (nearer 0.0f) and subsequent stops are treated as "higher" (nearer 1.0f). This behavior is useful if a caller wants an instant transition in the middle of a stop.

Typically, there are at least two points in a collection, although creation with only one stop is permitted. For example, one point is at position 0.0f, another point is at position 1.0f, and additional points are distributed in the [0, 1] range. Where the gradient progression is beyond the range of [0, 1], the stops are stored, but may affect the gradient.

When drawn, the [0, 1] range of positions is mapped to the brush, in a brush-dependent way. For details, see ID2D1LinearGradientBrush and ID2D1RadialGradientBrush.

Gradient stops with a position outside the [0, 1] range cannot be seen explicitly, but they can still affect the colors produced in the [0, 1] range. For example, a two-stop gradient {{0.0f, Black}, {2.0f, White}} is indistinguishable visually from {{0.0f, Black}, {1.0f, Mid-level gray}}. Also, the colors are clamped before interpolation.

Examples

The following example creates an array of gradient stops, then uses them to create an ID2D1GradientStopCollection.

// 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
    );

The next code example uses the ID2D1GradientStopCollection to create an ID2D1LinearGradientBrush.

// 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
        );
}

Requirements

See also

Brushes Overview

CreateGradientStopCollection

How to Create a Linear Gradient Brush

How to Create a Radial Gradient Brush

ID2D1GradientStopCollection

ID2D1LinearGradientBrush

ID2D1RadialGradientBrush