Function JxlDecoderExtraChannelBufferSize 

pub unsafe extern "C-unwind" fn JxlDecoderExtraChannelBufferSize(
    dec: *const JxlDecoder,
    format: *const JxlPixelFormat,
    size: *mut usize,
    index: u32,
) -> JxlDecoderStatus

Returns the minimum size in bytes of an extra channel pixel buffer for the given format. This is the buffer for JxlDecoderSetExtraChannelBuffer. Requires the basic image information is available in the decoder.

Parameters

• dec: decoder object
• format: format of the pixels. The num_channels value is ignored and is always treated to be 1.
• size: output value, buffer size in bytes
• index: which extra channel to get, matching the index used in JxlDecoderGetExtraChannelInfo. Must be smaller than num_extra_channels in the associated JxlBasicInfo.

Returns

• JxlDecoderStatus::Success on success
• JxlDecoderStatus::Error on error, such as information not available yet or invalid index.