Function JxlEncoderSetExtraChannelBuffer 

pub unsafe extern "C-unwind" fn JxlEncoderSetExtraChannelBuffer(
    frame_settings: *const JxlEncoderFrameSettings,
    pixel_format: *const JxlPixelFormat,
    buffer: *const c_void,
    size: usize,
    index: u32,
) -> JxlEncoderStatus

Sets the buffer to read pixels from for an extra channel at a given index. The index must be smaller than the num_extra_channels in the associated JxlBasicInfo. Must call JxlEncoderSetExtraChannelInfo before JxlEncoderSetExtraChannelBuffer.

TODO: mention what data types in pixel formats are supported.

It is required to call this function for every extra channel, except for the alpha channel if that was already set through JxlEncoderAddImageFrame.

Parameters

• frame_settings: Set of options and metadata for this frame. Also includes reference to the encoder object.
• pixel_format: Format for pixels. Object owned by the caller and its contents are copied internally. The num_channels value is ignored, since the number of channels for an extra channel is always assumed to be one.
• buffer: Buffer type to input the pixel data from. Owned by the caller and its contents are copied internally.
• size: Size of buffer in bytes. This size should match what is implied by the frame dimensions and the pixel format.
• index: Index of the extra channel to use.

Returns

• JxlEncoderStatus::Success on success.
• JxlEncoderStatus::Error on error.