Containers::Array<Color4ub> from ImageData2D

[hsdk123]

Looking for a Containers::Array from ImageData2D implementation as per gitter chat.

Use case: when ex. don't need to iterate over all pixels, but just need to fetch one or a certain portion continuously.

[mosra]

For the record (also grabbed from Gitter), this is (an untested) snippet that should work for most common image formats:

#include <Corrade/Utility/Algorithms.h> // for copy()

Containers::Array<Color4ub> outputData{std::size_t(image.size().product()), 
    Containers::DirectInit, Color4ub{0, 0, 0, 255}}; // set alpha to 1 by default
Containers::StridedArrayView2D<Color4ub> output{outputData, 
    {std::size_t(image.size().y()), std::size_t(image->size().x())}};
if(image.format() == PixelFormat::RGBA8Unorm) {
    Utility::copy(image.pixels<Color4ub>(), output);
} else if(image.format() == PixelFormat::RGB8Unorm) {
    Utility::copy(image.pixels<Color3ub>(), 
                  Containers::arrayCast<Color3ub>(output)); // alpha stays at 255
} else if(image.format() == PixelFormat::R8Unorm) {
    // broadcasts the red channel to RGB
    Utility::copy(Containers::arrayCast<const UnsignedByte>(image.pixels()).broadcast<2>(3), 
                  Containers::arrayCast<3, UnsignedByte>(output)); // alpha stays at 255
} else Fatal{} << "Oh noes!";