Merge pull request #1619 from deltachat/rotate-images

respect image orientation from exif on recoding

src/blob.rs

@@ -14,6 +14,7 @@ use thiserror::Error;
 use crate::config::Config;
 use crate::constants::*;
 use crate::context::Context;
+use crate::error::Error;
 use crate::events::Event;
 use crate::message;
 
@@ -408,7 +409,13 @@ impl<'a> BlobObject<'a> {
             return Ok(());
         }
 
-        let img = img.thumbnail(img_wh, img_wh);
+        let mut img = img.thumbnail(img_wh, img_wh);
+        match self.get_exif_orientation(context) {
+            Ok(90) => img = img.rotate90(),
+            Ok(180) => img = img.rotate180(),
+            Ok(270) => img = img.rotate270(),
+            _ => {}
+        }
 
         img.save(&blob_abs).map_err(|err| BlobError::WriteFailure {
             blobdir: context.get_blobdir().to_path_buf(),
@@ -418,6 +425,24 @@ impl<'a> BlobObject<'a> {
 
         Ok(())
     }
+
+    pub fn get_exif_orientation(&self, context: &Context) -> Result<i32, Error> {
+        let file = std::fs::File::open(self.to_abs_path())?;
+        let mut bufreader = std::io::BufReader::new(&file);
+        let exifreader = exif::Reader::new();
+        let exif = exifreader.read_from_container(&mut bufreader)?;
+        if let Some(orientation) = exif.get_field(exif::Tag::Orientation, exif::In::PRIMARY) {
+            // possible orientation values are described at http://sylvana.net/jpegcrop/exif_orientation.html
+            // we only use rotation, in practise, flipping is not used.
+            match orientation.value.get_uint(0) {
+                Some(3) => return Ok(180),
+                Some(6) => return Ok(90),
+                Some(8) => return Ok(270),
+                other => warn!(context, "exif orientation value ignored: {:?}", other),
+            }
+        }
+        Ok(0)
+    }
 }
 
 impl<'a> fmt::Display for BlobObject<'a> {