CCITT Group 4 / T.6 "fax machine" compression handling example

[hotspoons]

The maintainer of the fax crate was gracious enough to help me get CCITT group 4/T.6 compression support working with the tiff crate (see this) and he suggested I offer it as an example here. I'm just taking a guess for how you would want to include an example of this integration, so here it is!

[sophie-h]

This code looks quite clean. Maybe this could just be added as a feature to tiff? That would make the example redundant.

[fintelia]

Yeah, I'd be in favor of adding this as a feature to tiff. This is where we dispatch on which compression to use:

image-tiff/src/decoder/image.rs

Lines 361 to 370 in daa0e3e

	Ok(match compression_method {
	CompressionMethod::None => Box::new(reader),
	CompressionMethod::LZW => {
	Box::new(LZWReader::new(reader, usize::try_from(compressed_length)?))
	}
	CompressionMethod::PackBits => Box::new(PackBitsReader::new(reader, compressed_length)),
	CompressionMethod::Deflate | CompressionMethod::OldDeflate => {
	Box::new(DeflateReader::new(reader))
	}
	CompressionMethod::ModernJPEG => {

I do think it'll take a bit of effort though. The fax crate seems to sometimes panic if it encounters malformed input and it isn't immediately obvious whether we could handle incremental decompression (which helps both for perf and to avoid OOMs from specially crafted inputs)