[docs/example] example on how to interoperate with code expecting pixels as raw data

[planetmarshall]

A common task is to interoperate with code expecting data as raw bytes, eg as a single contiguous array or as an array of padded scanlines.

It would be great to have an example and an entry in the docs.

I'd be happy to make a contribution but the reason I'm asking about it is that I'm not exactly sure how best to do it, short of just copying pixel-by-pixel.

[sdebionne]

I believe that what you are looking for is documented here:

https://www.boost.org/doc/libs/latest/libs/gil/doc/html/reference/group___image_view_constructors.html

Does that fit your needs ?

[planetmarshall]

I believe that what you are looking for is documented here:

https://www.boost.org/doc/libs/latest/libs/gil/doc/html/reference/group___image_view_constructors.html

Does that fit your needs ?

Possibly. Unfortunately that documentation is not readable for me. Possibly something to do with the stylesheet?

[planetmarshall]

Possibly. Unfortunately that documentation is not readable for me. Possibly something to do with the stylesheet?

Raised a separate issue #782

[sdebionne]

Indeed this is unfortunate.

// from raw CMYK planar data:

template<typename IC >
auto planar_cmyk_view (std::size_t width, std::size_t height, IC c, IC m, IC y, IC k, std::ptrdiff_t rowsize_in_bytes) -> typename type_from_x_iterator< planar_pixel_iterator< IC, cmyk_t > >::view_t
 
// from 2-channel planar data:

template<typename IC >
auto planar_devicen_view (std::size_t width, std::size_t height, IC c0, IC c1, std::ptrdiff_t rowsize_in_bytes) -> typename type_from_x_iterator< planar_pixel_iterator< IC, devicen_t< 2 > > >::view_t
 
// from 3-channel planar data:

template<typename IC >
auto planar_devicen_view (std::size_t width, std::size_t height, IC c0, IC c1, IC c2, std::ptrdiff_t rowsize_in_bytes) -> typename type_from_x_iterator< planar_pixel_iterator< IC, devicen_t< 3 > > >::view_t

...

// Constructing image views from raw interleaved pixel data:
 
template<typename Iterator >
auto interleaved_view (std::size_t width, std::size_t height, Iterator pixels, std::ptrdiff_t rowsize_in_bytes) -> typename type_from_x_iterator< Iterator >::view_t
 
template<typename Iterator >
auto interleaved_view (point< std::ptrdiff_t > dim, Iterator pixels, std::ptrdiff_t rowsize_in_bytes) -> typename type_from_x_iterator< Iterator >::view_t
 
// Returns C pointer to the the channels of an interleaved homogeneous view:

template<typename HomogeneousView >
auto interleaved_view_get_raw_data (HomogeneousView const &view) -> typename detail::channel_pointer_type< HomogeneousView >::type
 
template<typename HomogeneousView >
auto planar_view_get_raw_data (HomogeneousView const &view, int plane_index) -> typename detail::channel_pointer_type< HomogeneousView >::type
 
// from raw RGB planar data:

template<typename IC >
auto planar_rgb_view (std::size_t width, std::size_t height, IC r, IC g, IC b, std::ptrdiff_t rowsize_in_bytes) -> typename type_from_x_iterator< planar_pixel_iterator< IC, rgb_t > >::view_t
 
// from raw RGBA planar data:

template<typename ChannelPtr >
auto planar_rgba_view (std::size_t width, std::size_t height, ChannelPtr r, ChannelPtr g, ChannelPtr b, ChannelPtr a, std::ptrdiff_t rowsize_in_bytes) -> typename type_from_x_iterator< planar_pixel_iterator< ChannelPtr, rgba_t > >::view_t

[planetmarshall]

Many thanks for that - I have something working now. I still think an example and a note in the docs would be useful as it wasn't immediately obvious to me how to do this - but I'm happy to contribute something.

[mloskot]

Please, @planetmarshall, feel encouraged to contribute to the docs.