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, 2 insertions, 1 deletions

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index a38569f7263..4b10788862e 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -5992,7 +5992,8 @@ Decrease the image size (@code{image-increase-size}).  A prefix value
 of @samp{4} means to decrease the size by 40%.  The default is 20%.
 
 @item r
-Rotate the image by 90 degrees (@code{image-rotate}).
+Rotate the image by 90 degrees clockwise (@code{image-rotate}).
+A prefix means to rotate by 90 degrees counter-clockwise instead.
 
 @item o
 Save the image to a file (@code{image-save}).