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boostorg / gil

Boost.GIL - Generic Image Library | Requires C++14 since Boost 1.80
https://boostorg.github.io/gil
Boost Software License 1.0
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Fixed int -> float truncation warning in pixel.hpp #689

Closed jsenn closed 2 years ago

jsenn commented 2 years ago

Description

The underlying channel type for grayscale pixels is a 32-bit float. If Channel cannot be losslessly converted to a float--for example, if it is int--this would generate a compiler warning. The fix here is to perform an explicit cast. Fixes #688.

References

See related issue: #688.

jsenn commented 2 years ago

The proposed change fixes the warning for the sample code given, but fails template instantiation for pixels that have a raw channel type (i.e., that don't use scoped_channel_value).

Also, on further inspection I'm not sure that a simple cast is even warranted here--the warning in #688 results from a piece of code in numeric.hpp that's multiplying 2 shorts (producing an int) and then assigning it to a 32-bit float grayscale pixel (which is scoped to [0, 1]). I'm not sure what the correct behaviour even is there, so I'll close this and let someone more knowledgeable figure this out.