aviary-cli/src/thumbnailing.rs

use std::io::Cursor;
use image::{io::Reader, DynamicImage, ImageResult, ImageFormat};
use webp::{Encoder, WebPMemory};

use crate::protobuf::image::Format;

pub fn thumbnail(bytes: &[u8]) -> ImageResult<(Option<WebPMemory>, u32, u32, WebPMemory, String, Format)> {
	let original_image_encoded = Reader::new(Cursor::new(bytes))
		.with_guessed_format().expect("IO errors impossible with Cursor");
	let original_format = original_image_encoded.format();
	let original_image = original_image_encoded.decode()?;

	let new_dimm = u32::min(original_image.height(), original_image.width());
	let crop_x = (original_image.width() - new_dimm) / 2;
	let crop_y = (original_image.height() - new_dimm) / 2;
	let cropped = original_image.crop_imm(crop_x, crop_y, new_dimm, new_dimm);
	let scaled = if new_dimm < 400 {
		cropped
	} else {
		cropped.thumbnail_exact(400, 400)
	}.into_rgba8();
	let scale = scaled.width();

	let blurhash = blurhash::encode(4, 4, scale, scale, scaled.as_raw());

	let (recoded_original, format) = match original_format {
		Some(ImageFormat::WebP) => (None, Format::WEBP),
		Some(ImageFormat::Avif) => (None, Format::AVIF),
		Some(ImageFormat::Jpeg) => (None, Format::JPG),
		Some(ImageFormat::Png) => (None, Format::PNG),
		Some(ImageFormat::Gif) => (None, Format::GIF),
		_ => ( // Unrecognized or format which isn't spec-supported
			Some(
				Encoder::from_image(&original_image)
					.expect("Error transcoding image as webp")
					.encode_lossless(),
			),
			Format::WEBP
		)
	};

	Ok((
		recoded_original,
		original_image.width(),
		original_image.height(),
		Encoder::from_image(&DynamicImage::ImageRgba8(scaled))
			.expect("Unexpected difficulty interpretting thumbnail")
			.encode(50.0),
		blurhash,
		format,
	))
}