feat: compute thumbhash for images (#596)

* feat: compute thumbhash for images

Signed-off-by: newt <hi@newty.dev>

* Merge branch 'main' into feat/thumbhash

Signed-off-by: newt <hi@newty.dev>

* style: move comment onto newline

Signed-off-by: newt <hi@newty.dev>

* feat: make thumbhash optional

Signed-off-by: newt <hi@newty.dev>

---------

Signed-off-by: newt <hi@newty.dev>
Signed-off-by: newt (: <hi@newty.dev>
Signed-off-by: Tom <iamtomahawkx@gmail.com>
Co-authored-by: Tom <iamtomahawkx@gmail.com>

crates/services/autumn/Cargo.toml

@@ -17,6 +17,7 @@ jxl-oxide = "0.8.1"
 kamadak-exif = "0.5.4"
 # revolt_little_exif = "0.5.1"
 image = { version = "0.25.2" } # avif encode requires dav1d system library: features = ["avif-native"]
+thumbhash = "0.1.0"
 
 # File processing
 revolt_clamav-client = { version = "0.1.5" }

crates/services/autumn/src/exif.rs

@@ -19,6 +19,7 @@ pub async fn strip_metadata(
         Metadata::Image {
             width,
             height,
+            thumbhash,
             animated,
         } => match mime {
             // // little_exif does not appear to parse JPEGs correctly? had 2/2 files fail
@@ -102,6 +103,7 @@ pub async fn strip_metadata(
                     Metadata::Image {
                         width,
                         height,
+                        thumbhash: thumbhash.clone(),
                         animated: *animated,
                     },
                 ))

crates/services/autumn/src/metadata.rs

@@ -1,5 +1,6 @@
 use std::io::Cursor;
 
+use image::{GenericImageView, ImageError, ImageReader};
 use revolt_database::Metadata;
 use revolt_files::{image_size, is_animated, video_size};
 use tempfile::NamedTempFile;
@@ -26,6 +27,16 @@ pub fn generate_metadata(f: &NamedTempFile, mime_type: &str) -> Metadata {
             .map(|(width, height)| Metadata::Image {
                 width: width as isize,
                 height: height as isize,
+                thumbhash: ImageReader::open(f)
+                    .and_then(|r| r.with_guessed_format())
+                    .map_err(ImageError::from)
+                    .and_then(|r| r.decode())
+                    .map(|img| img.thumbnail(100, 100))
+                    .map(|img| (img.dimensions(), img.to_rgba8().into_raw()))
+                    .map(|((width, height), rgba)| {
+                        thumbhash::rgba_to_thumb_hash(width as usize, height as usize, &rgba)
+                    })
+                    .ok(),
                 animated: is_animated(f, mime_type).unwrap_or(false),
             })
             .unwrap_or_default()