Re: image-rotate: Accept angle as an argument

[Tino Calancha <tino.calancha@gmail.com>]

On Mon, 5 Sep 2016, Tino Calancha wrote:

>
> Hello,
> lisp/image.el defines 'image-increase-size' and 'image-decrease-size',
> with an argument N.  We might allow for an argument in 'image-rotate'
> as well.

I would like also to modify 'image-increase-size' and 
'image-decrease-size' as i did with 'image-rotate':
A prefix argument prompt user for the size factor.  Then you can perform 
arbitrary rotations and resize of an image using these commands as 
follows:
;; FILE is the file name of an image file:
emacs -Q FILE:
1 r 15 RET ; rotate image 15 degrees
1 r -15 RET ; rotate image -15 degrees
1 + 50 RET ; increase image size 50%
1 - 40 RET ; decrease image size 40%

So the proposal is 2 patches:

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From aefda287d0d739c99f6e45f568a22b67f1eb19da Mon Sep 17 00:00:00 2001
From: Tino Calancha <tino.calancha@gmail.com>
Date: Mon, 5 Sep 2016 16:26:03 +0900
Subject: [PATCH 1/2] image-rotate: Accept angle as an argument

* lisp/image.el (image-rotate):
Add argument ANGLE, the angle in degrees for the rotation.
Add optional argument _ARG; in interactive calls, a non-nil
value prompt for ANGLE.
---
  lisp/image.el | 17 +++++++++++++----
  1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/lisp/image.el b/lisp/image.el
index e1f52de..cad8332 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -1008,12 +1008,21 @@ image--current-scaling
          (display-width (car (image-size image t))))
      (/ (float display-width) image-width)))

-(defun image-rotate ()
-  "Rotate the image under point by 90 degrees clockwise."
-  (interactive)
+(defun image-rotate (angle &optional _arg)
+  "Rotate the image under point by ANGLE degrees clockwise.
+If ANGLE is a negative number, then rotate counterclockwise.
+When called interactively with a prefix argument, prompt for ANGLE."
+  (interactive
+   (let* ((ask current-prefix-arg)
+          (default 90)
+          (prompt "Rotate image by ANGLE degrees: ")
+          (rotation (if ask
+                        (read-number prompt default)
+                      default)))
+     (list rotation ask)))
    (let ((image (image--get-imagemagick-and-warn)))
      (plist-put (cdr image) :rotation
-               (float (mod (+ (or (plist-get (cdr image) :rotation) 0) 
90)
+               (float (mod (+ (or (plist-get (cdr image) :rotation) 0) 
angle)
                             ;; We don't want to exceed 360 degrees
                             ;; rotation, because it's not seen as valid
                             ;; in exif data.
-- 
2.9.3

From 7428267a2723315e9a8df3f7a687aeb66513dde4 Mon Sep 17 00:00:00 2001
From: Tino Calancha <tino.calancha@gmail.com>
Date: Mon, 5 Sep 2016 16:29:56 +0900
Subject: [PATCH 2/2] image-increase-size: Prompt for size factor in
  interactive calls

* lisp/image.el (image-increase-size, image-decrease-size):
Add optional argument _ARG; in interactive calls, a non-nil
value prompt for the size factor.
---
  lisp/image.el | 43 ++++++++++++++++++++++++++++---------------
  1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/lisp/image.el b/lisp/image.el
index cad8332..1bfa042 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -951,23 +951,36 @@ imagemagick-enabled-types

  (imagemagick-register-types)

-(defun image-increase-size (n)
-  "Increase the image size by a factor of N.
+(defun image-increase-size (n &optional _arg)
+  "Increase the image size.
  If N is 3, then the image size will be increased by 30%.  The
-default is 20%."
-  (interactive "P")
-  (image--change-size (if n
-                          (1+ (/ n 10.0))
-                        1.2)))
-
-(defun image-decrease-size (n)
-  "Decrease the image size by a factor of N.
+default is 20%.
+When called interactively with a prefix argument, prompt for N."
+  (interactive
+   (let* ((ask current-prefix-arg)
+          (default 20)
+          (num (if ask
+                   (read-number "Increase image size by X %: " default)
+                 default)))
+     (list (/ num 10.0) ask)))
+  (image--change-size (1+ (/ n 10.0))))
+
+(defun image-decrease-size (n &optional _arg)
+  "Decrease the image size.
  If N is 3, then the image size will be decreased by 30%.  The
-default is 20%."
-  (interactive "P")
-  (image--change-size (if n
-                          (- 1 (/ n 10.0))
-                        0.8)))
+default is 20%.
+When called interactively with a prefix argument, prompt for N."
+  (interactive
+   (let* ((ask current-prefix-arg)
+          (default 20)
+          (num (if ask
+                   (read-number "Decrease image size by X %: " default)
+                 default)))
+     (list (/ num 10.0) ask)))
+  (let ((decrease (/ n 10.0)))
+    (image--change-size (if (< decrease 1)
+                            (- 1 decrease)
+                          0))))

  (defun image--get-image ()
    (let ((image (get-text-property (point) 'display)))
-- 
2.9.3

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In GNU Emacs 25.1.50.1 (x86_64-pc-linux-gnu, GTK+ Version 3.20.9)
  of 2016-09-05
Repository revision: 62e4dc4660cb3b29cfffcad0639e51c7f382ced8