ID2D1DeviceContext::CreateGradientStopCollection method

Creates a gradient stop collection, enabling the gradient to contain color channels with values outside of [0,1] and also enabling rendering to a high-color render target with interpolation in sRGB space.

Syntax

HRESULT CreateGradientStopCollection(
  const D2D1_GRADIENT_STOP      *straightAlphaGradientStops,
  UINT32                        straightAlphaGradientStopsCount,
  D2D1_COLOR_SPACE              preInterpolationSpace,
  D2D1_COLOR_SPACE              postInterpolationSpace,
  D2D1_BUFFER_PRECISION         bufferPrecision,
  D2D1_EXTEND_MODE              extendMode,
  D2D1_COLOR_INTERPOLATION_MODE colorInterpolationMode,
  ID2D1GradientStopCollection1  **gradientStopCollection1
);

Parameters

straightAlphaGradientStops

Type: const D2D1_GRADIENT_STOP*

An array of color values and offsets.

straightAlphaGradientStopsCount

Type: UINT

The number of elements in the gradientStops array.

preInterpolationSpace

Type: D2D1_COLOR_SPACE

Specifies both the input color space and the space in which the color interpolation occurs.

postInterpolationSpace

Type: D2D1_COLOR_SPACE

The color space that colors will be converted to after interpolation occurs.

bufferPrecision

Type: D2D1_BUFFER_PRECISION

The precision of the texture used to hold interpolated values.

Note  This method will fail if the underlying Direct3D device does not support the requested buffer precision. Use ID2D1DeviceContext::IsBufferPrecisionSupported to determine what is supported.
 

extendMode

Type: D2D1_EXTEND_MODE

Defines how colors outside of the range defined by the stop collection are determined.

colorInterpolationMode

Type: D2D1_COLOR_INTERPOLATION_MODE

Defines how colors are interpolated. D2D1_COLOR_INTERPOLATION_MODE_PREMULTIPLIED is the default, see Remarks for more info.

gradientStopCollection1

Type: ID2D1GradientStopCollection1**

The new gradient stop collection.

Return Value

Type: HRESULT

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

HRESULT Description
S_OK No error occurred.
E_OUTOFMEMORY Direct2D could not allocate sufficient memory to complete the call.
E_INVALIDARG An invalid value was passed to the method.

Remarks

This method linearly interpolates between the color stops. An optional color space conversion is applied post-interpolation. Whether and how this gamma conversion is applied is determined by the pre- and post-interpolation. This method will fail if the device context does not support the requested buffer precision.

In order to get the desired result, you need to ensure that the inputs are specified in the correct color space.

You must always specify colors in straight alpha, regardless of interpolation mode being premultiplied or straight. The interpolation mode only affects the interpolated values. Likewise, the stops returned by ID2D1GradientStopCollection::GetGradientStops will always have straight alpha.

If you specify D2D1_COLOR_INTERPOLATION_MODE_PREMULTIPLIED, then all stops are premultiplied before interpolation, and then un-premultiplied before color conversion.

Starting with Windows 8, the interpolation behavior of this method has changed.

The table here shows the behavior in Windows 7 and earlier.

Gamma Before Interpolation Behavior After Interpolation Behavior GetColorInteroplationGamma (output color space)
1.0 Clamps the inputs and then converts from sRGB to scRGB. Converts from scRGB to sRGB post-interpolation. 1.0
2.2 Clamps the inputs. No Operation 2.2
 

The table here shows the behavior in Windows 8 and later.

Gamma Before Interpolation Behavior After Interpolation Behavior GetColorInteroplationGamma (output color space)
sRGB to scRGB No Operation Clamps the outputs and then converts from sRGB to scRGB. 1.0
scRGB to sRGB No Operation Clamps the outputs and then converts from sRGB to scRGB. 2.2
sRGB to sRGB No Operation No Operation 2.2
scRGB to scRGB No Operation No Operation 1.0

Requirements

   
Minimum supported client Windows 8 and Platform Update for Windows Vista [desktop apps | UWP apps]
Minimum supported server Windows Server 2012 and Platform Update for Windows Server 2008 [desktop apps | UWP apps]
Target Platform Windows
Header d2d1_1.h
DLL D2d1.dll

See Also

D2D1_BUFFER_PRECISION

D2D1_EXTEND_MODE

D2D1_GAMMA_CONVERSION

D2D1_GRADIENT_STOP

ID2D1DeviceContext

ID2D1GradientStopCollection1

ID2D1RenderTarget::CreateGradientStopCollection