Allow counter-clockwise rotations in image-rotate

* lisp/image.el (image-rotate): Extend with an optional argument
specifying the rotation in degrees (bug#35421).
* doc/lispref/display.texi (Showing Images):
* etc/NEWS: Document the change.
* test/lisp/image-tests.el (image-rotate): New test.

1 files changed, 23 insertions, 0 deletions

diff --git a/test/lisp/image-tests.el b/test/lisp/image-tests.el
index 5a5b8ea1f71..01c81e3022f 100644
--- a/test/lisp/image-tests.el
+++ b/test/lisp/image-tests.el
@@ -21,6 +21,8 @@
 
 (require 'ert)
 (require 'image)
+(eval-when-compile
+  (require 'cl-lib))
 
 (defconst image-tests--emacs-images-directory
   (expand-file-name "../etc/images" (getenv "EMACS_TEST_DIRECTORY"))
@@ -53,4 +55,25 @@
                (expand-file-name "splash.svg"
                                  image-tests--emacs-images-directory)))))
 
+(ert-deftest image-rotate ()
+  "Test `image-rotate'."
+  (cl-letf* ((image (list 'image))
+             ((symbol-function 'image--get-imagemagick-and-warn)
+              (lambda () image)))
+    (let ((current-prefix-arg '(4)))
+      (call-interactively #'image-rotate))
+    (should (equal image '(image :rotation 270.0)))
+    (call-interactively #'image-rotate)
+    (should (equal image '(image :rotation 0.0)))
+    (image-rotate)
+    (should (equal image '(image :rotation 90.0)))
+    (image-rotate 0)
+    (should (equal image '(image :rotation 90.0)))
+    (image-rotate 1)
+    (should (equal image '(image :rotation 91.0)))
+    (image-rotate 1234.5)
+    (should (equal image '(image :rotation 245.5)))
+    (image-rotate -154.5)
+    (should (equal image '(image :rotation 91.0)))))
+
 ;;; image-tests.el ends here