Fix rotations.

src/pixie/fileformats/jpeg.nim

@@ -988,16 +988,16 @@ proc buildImage(state: var DecoderState): Image =
       result.flipVertical()
     of 5:
       result.rotate90()
+      result.flipHorizontal()
     of 6:
       result.rotate90()
-      result.flipHorizontal()
     of 7:
       result.rotate90()
       result.flipVertical()
-      result.flipHorizontal()
     of 8:
       result.rotate90()
       result.flipVertical()
+      result.flipHorizontal()
     else:
       failInvalid("invalid orientation")
 

src/pixie/images.nim

@@ -171,11 +171,12 @@ proc flipVertical*(image: Image) {.raises: [].} =
       )
 
 proc rotate90*(image: Image) {.raises: [PixieError].} =
-  ## Rotates the image 90 degrees.
+  ## Rotates the image 90 degrees clockwise.
   var copy = newImage(image.height, image.width)
   for y in 0 ..< copy.height:
     for x in 0 ..< copy.width:
-      copy.data[copy.dataIndex(x, y)] = image.data[image.dataIndex(y, x)]
+      copy.data[copy.dataIndex(x, y)] =
+        image.data[image.dataIndex(y, image.height - x - 1)]
   image.width = copy.width
   image.height = copy.height
   image.data = copy.data