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# CVFillExtendedPixelsCallBackData

A structure for holding information that describes a custom extended pixel fill algorithm.

```
struct CVFillExtendedPixelsCallBackData
```

## Overview

You must fill out this structure and store it as part of your pixel format description Core Foundation dictionary (key: `kCVPixelFormatFillExtendedPixelsCallback`, type: `CFData`). However, if your custom pixel format never needs the functionality of [`CVPixelBufferFillExtendedPixels(_:)`](/documentation/CoreVideo/CVPixelBufferFillExtendedPixels(_:)), you don’t need to add this key or implement the associated callback.

For more information about defining a custom pixel format, see [Pixel Format Description Keys](/documentation/CoreVideo/pixel-format-description-keys).

## Topics

### Initializers

[`init()`](/documentation/CoreVideo/CVFillExtendedPixelsCallBackData/init())

[`init(version:fillCallBack:refCon:)`](/documentation/CoreVideo/CVFillExtendedPixelsCallBackData/init(version:fillCallBack:refCon:))

### Properties

[`fillCallBack`](/documentation/CoreVideo/CVFillExtendedPixelsCallBackData/fillCallBack)

[`refCon`](/documentation/CoreVideo/CVFillExtendedPixelsCallBackData/refCon)

A pointer to application-defined data that is passed to your custom pixel fill function.

[`version`](/documentation/CoreVideo/CVFillExtendedPixelsCallBackData/version)

The version of this fill algorithm.


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