How do I create a PixelFormat to pass to Surface.from() ?

[avrame]

I'm trying to render an image that I created with Blend2d.cr. I passed in the bytes of the image in the first argument, the width, and height next. But I don't know how to create a PixelFormat instance to pass in as the fourth argument.

[ysbaddaden]

You can use SDL::Image.load to load an image as a SDL::Surface or directly render it to a SDL::Renderer.

The alternative would be to decode the image into a flat byte buffer and respect one of the pixel format or create a specific one so SDL can know where each pixel is in the buffer and how to interpret the bytes as pixel colors (too much hassle).

[avrame]

Thanks for the quick response @ysbaddaden I'm trying to work with the raw pixel data from the Blend2D rendering as creating an image and then loading it is too slow. I want it fast enough to run at 60+ fps. Is there a different way to do this with SDL or should I try a library more suited to this?

[ysbaddaden]

Oh, then you need to know the byte format for a Blend2D::Image buffer (preferably) or a mean to translate to a known format (RGBA32).

Most of the pixels related C functions don't have a binding, but you may write some. I noticed LibC::SDL_PixelFormatEnum has a RGBA32 member (for example) then I found
https://stackoverflow.com/a/32000743 that reports that we can use LibC::SDL_AllocFormat to get a LibC::SDL_PixelFormat* for a given enum!

Toying with this, you should eventually be able to render from blend2d to sdl.

[avrame]

That worked great - thanks! I forked this library and made a few updates to get it working. I can make a PR later - maybe after the holidays.