Thumbnail quality options

[aaronleopold]

I'd like to add additional configuration options around thumbnail generation. Primarily, I'd like to support the following:

• JPG, JPEG-XL, WEBP export format (currently only WEBP)
• Customizable scale factor (0-1, default currently is 0.75)
• Customizable dimensions (maybe, might be too much of a hassle)

I will need to decide whether this should be library or server level options.

General tasks:

• Create generalized wrapper function in my image crate that handles the conversion
  • should accept the options selected from user
• Update WEBP conversion to accept options
• Create functions to convert buffer to:
  • JPG
  • JPEG-XL
  • WEBP
  • PNG

[berkingurcan]

I can take it

[aaronleopold]

Hey @berkingurcan thanks! Sorry for the late reply, been extra busy lately. Here you'll find all of the image thumbnail generation logic.

Essentially, what I was thinking was to update what's there, and add a few new functions for the new formats, to allow future custom scaling options. Something like:

/// The size factor to use when generating a thumbnail. This can be a
/// scaled factor, where the height and width are scaled by the same factor, a
/// a custom factor, where the height and width are scaled by different factors,
/// or a specific size, where the height and width are set to the specified size.
/// 
/// All floats are clamped to the range [0.0, 1.0].
pub enum ThumbnailSizeFactor {
	Scaled(f32),
	CustomScaled((f32, f32)),
	Sized((u32, u32)),
}

/// The format to use when generating a thumbnail.
pub enum ThumbnailFormat {
	Webp,
	Jpeg,
	JpegXl,
	Png,
}

pub struct ThumbnailConfig {
	pub size_factor: ThumbnailSizeFactor,
	pub format: ThumbnailFormat,
}

impl Default for ThumbnailConfig {
	fn default() -> Self {
		Self {
			size_factor: ThumbnailSizeFactor::Scaled(0.5),
			format: ThumbnailFormat::Webp,
		}
	}
}

So the thumbnail functions would take a reference to a ThumbnailConfig that controls some of the hard coded values throughout that file. It might be worth while to consider splitting my image.rs into a crate with multiple modules per format, and have some sort of factory pattern for uniformity. E.g:

• image/jpg.rs
  • from_path
  • from_bytes
• image/png.rs
  • from_path
  • from_bytes
• etc

But, I'll leave that up to you. I think for now you can leave the jpeg-xl format alone, since it would require pulling in https://github.com/inflation/jpegxl-rs, but if you want to try it feel free.

[aaronleopold]

Resolved from #134