respect exif image orientation in previews

Cargo.toml

@@ -87,7 +87,7 @@ default = [
 ]
 desktop = ["webbrowser", "opener", "is_executable"]
 previews = []
-previews-image = ["image", "webp"]
+previews-image = ["image", "webp", "kamadak-exif"]
 extractors-web = ["webpage"]
 extractors-audio = ["id3"]
 extractors-photo = ["kamadak-exif"]

src/previews/image.rs

@@ -14,7 +14,28 @@ impl<'a> Previewable for ImagePath<'a> {
     fn get_thumbnail(&self) -> Result<Option<Vec<u8>>> {
         #[cfg(feature = "previews-image")]
         {
+            let file = std::fs::File::open(&self.0)?;
+            let mut bufreader = std::io::BufReader::new(&file);
+            let exifreader = exif::Reader::new();
+            let orientation = exifreader
+                .read_from_container(&mut bufreader)
+                .ok()
+                .and_then(|exif| {
+                    exif.get_field(exif::Tag::Orientation, exif::In::PRIMARY)
+                        .and_then(|f| match &f.value {
+                            exif::Value::Short(shorts) => Some(shorts.clone()),
+                            _ => None,
+                        })
+                })
+                .and_then(|shorts| shorts.first().cloned());
+
             let image = ImageReader::open(&self.0)?.decode()?;
+            let image = match orientation {
+                Some(3) => image.rotate180(),
+                Some(6) => image.rotate90(),
+                Some(8) => image.rotate270(),
+                _ => image
+            };
             let (w, h) = image.dimensions();
             if cmp::max(w, h) > 1024 {
                 let thumbnail = image.thumbnail(1024, 1024);