ID2D1DeviceContext::CreateGradientStopCollection method (d2d1_1.h)
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,
[out] 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.
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.
[out] 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
| Requirement | Value |
|---|---|
| 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 |