Apply EXIF orientation when converting images with ImageMagick

Photos taken on phones store pixels unrotated with an EXIF Orientation
tag. Converting them to formats where the tag is lost or ignored (png,
webp, ...) produced sideways images. Add -auto-orient so the pixels are
rotated according to the tag before writing the output.

Author: casi-3

src/converters/imagemagick.ts

@@ -468,6 +468,10 @@ export function convert(
     outputArgs.push("-background", "white", "-alpha", "remove");
   }
 
+  // Apply EXIF orientation so photos (e.g. from phones) don't end up sideways
+  // when converted to formats where the orientation tag is lost or ignored
+  outputArgs.push("-auto-orient");
+
   return new Promise((resolve, reject) => {
     execFile(
       "magick",

tests/converters/imagemagick.test.ts

@@ -163,3 +163,19 @@ test("convert respects emf as input filetype", async () => {
   );
   expect(loggedMessage).toBe("stdout: Fake stdout");
 });
+
+test("convert applies EXIF auto-orient", async () => {
+  const mockExecFile: ExecFileFn = (
+    _cmd: string,
+    _args: string[],
+    callback: (err: ExecFileException | null, stdout: string, stderr: string) => void,
+  ) => {
+    calls.push(_args);
+    callback(null, "", "");
+  };
+
+  const result = await convert("input.jpg", "jpg", "png", "output.png", undefined, mockExecFile);
+
+  expect(result).toBe("Done");
+  expect(calls[0]).toEqual(expect.arrayContaining(["input.jpg", "-auto-orient", "output.png"]));
+});