# \#cairo

**URL:** https://racket.discourse.group/tag/cairo/36.md

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## [How to safely cast a \_pointer to \_bytes?](https://racket.discourse.group/t/how-to-safely-cast-a-pointer-to-bytes/364)

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**Author:** [@kurinoku](https://racket.discourse.group/u/kurinoku)\
**Replies:** 6\
**Last updated:** [December 6, 2021, 7:26pm UTC](https://racket.discourse.group/t/how-to-safely-cast-a-pointer-to-bytes/364 "2021-12-06T19:26:07Z")

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I'm using racket/draw/unsafe/cairo and a custom ffi for MagickWand C API. I have this definition, you can see the last parameter is \_bytes. (define-mwand MagickExportImagePixels (\_fun \_MagickWand-pointer \_size \_size \_s…