Use lexical-binding for Gravatar support

For discussion, see the following thread:
https://lists.gnu.org/archive/html/emacs-devel/2019-07/msg00528.html
* lisp/gnus/gnus-gravatar.el: Use lexical-binding.  Link custom
group 'gnus-gravatar' to 'gravatar'.
(gnus-gravatar-size, gnus-gravatar-too-ugly): Doc fix.
(gnus-gravatar-insert): Check liveness of article buffer sooner.
(gnus-treat-from-gravatar, gnus-treat-mail-gravatar): Use
interactive spec "p" instead of emulating it.
* lisp/image/gravatar.el: Use lexical-binding.
(gravatar-cache-expired): Remove.  Change all callers to use
url-cache-expired instead.
(gravatar-get-data, gravatar-retrieve)
(gravatar-retrieve-synchronously): Simplify.

2 files changed, 71 insertions, 90 deletions

diff --git a/lisp/gnus/gnus-gravatar.el b/lisp/gnus/gnus-gravatar.el
index 19cbf529c65..ec3f909161f 100644
--- a/lisp/gnus/gnus-gravatar.el
+++ b/lisp/gnus/gnus-gravatar.el
@@ -1,9 +1,9 @@
-;;; gnus-gravatar.el --- Gnus Gravatar support
+;;; gnus-gravatar.el --- Gnus Gravatar support -*- lexical-binding: t -*-
 
 ;; Copyright (C) 2010-2019 Free Software Foundation, Inc.
 
 ;; Author: Julien Danjou <julien@danjou.info>
-;; Keywords: news
+;; Keywords: multimedia, news
 
 ;; This file is part of GNU Emacs.
 
@@ -29,13 +29,15 @@
 (require 'mail-extr) ;; Because of binding `mail-extr-disable-voodoo'.
 
 (defgroup gnus-gravatar nil
-  "Gnus Gravatar."
+  "Gravatars in Gnus."
+  :link '(custom-group-link gravatar)
   :group 'gnus-visual)
 
 (defcustom gnus-gravatar-size nil
-  "How big should gravatars be displayed.
+  "Size in pixels at which gravatars should be displayed.
 If nil, default to `gravatar-size'."
-  :type '(choice (const nil) integer)
+  :type '(choice (const :tag "Default" nil)
+                 (integer :tag "Pixels"))
   :version "24.1"
   :group 'gnus-gravatar)
 
@@ -48,7 +50,7 @@ If nil, default to `gravatar-size'."
 (defcustom gnus-gravatar-too-ugly gnus-article-x-face-too-ugly
   "Regexp matching posters whose avatar shouldn't be shown automatically.
 If nil, show all avatars."
-  :type '(choice regexp (const nil))
+  :type '(choice regexp (const :tag "Allow all" nil))
   :version "24.1"
   :group 'gnus-gravatar)
 
@@ -74,56 +76,57 @@ If nil, show all avatars."
           (ignore-errors
             (gravatar-retrieve
              (cadr address)
-             'gnus-gravatar-insert
+             #'gnus-gravatar-insert
              (list header address category))))))))
 
 (defun gnus-gravatar-insert (gravatar header address category)
   "Insert GRAVATAR for ADDRESS in HEADER in current article buffer.
-Set image category to CATEGORY."
+Set image category to CATEGORY.  This function is intended as a
+callback for `gravatar-retrieve'."
   (unless (eq gravatar 'error)
     (gnus-with-article-buffer
-      (let ((mark (point-marker))
-            (inhibit-point-motion-hooks t)
-            (case-fold-search t))
-        (save-restriction
-          (article-narrow-to-head)
-          ;; The buffer can be gone at this time
-          (when (buffer-live-p (current-buffer))
+      ;; The buffer can be gone at this time.
+      (when (buffer-live-p (current-buffer))
+        (let ((real-name (car address))
+              (mail-address (cadr address))
+              (mark (point-marker))
+              (inhibit-point-motion-hooks t)
+              (case-fold-search t))
+          (save-restriction
+            (article-narrow-to-head)
             (gnus-article-goto-header header)
             (mail-header-narrow-to-field)
-            (let ((real-name (car address))
-                  (mail-address (cadr address)))
-              (when (if real-name
-                        (re-search-forward
-                         (concat (replace-regexp-in-string
-                                  "[\t ]+" "[\t\n ]+"
-                                  (regexp-quote real-name))
-                                 "\\|"
-                                 (regexp-quote mail-address))
-                         nil t)
-                      (search-forward mail-address nil t))
-                (goto-char (1- (match-beginning 0)))
-                ;; If we're on the " quoting the name, go backward
-                (when (looking-at "[\"<]")
-                  (goto-char (1- (point))))
-                ;; Do not do anything if there's already a gravatar. This can
-                ;; happens if the buffer has been regenerated in the mean time, for
-                ;; example we were fetching someaddress, and then we change to
-                ;; another mail with the same someaddress.
-                (unless (memq 'gnus-gravatar (text-properties-at (point)))
-                  (let ((point (point)))
-                    (setq gravatar (append gravatar gnus-gravatar-properties))
-                    (gnus-put-image gravatar (buffer-substring (point) (1+ point)) category)
-                    (put-text-property point (point) 'gnus-gravatar address)
-                    (gnus-add-wash-type category)
-                    (gnus-add-image category gravatar)))))))
-        (goto-char (marker-position mark))))))
+            (when (if real-name
+                      (re-search-forward
+                       (concat (replace-regexp-in-string
+                                "[\t ]+" "[\t\n ]+"
+                                (regexp-quote real-name))
+                               "\\|"
+                               (regexp-quote mail-address))
+                       nil t)
+                    (search-forward mail-address nil t))
+              (goto-char (1- (match-beginning 0)))
+              ;; If we're on the " quoting the name, go backward.
+              (when (looking-at-p "[\"<]")
+                (goto-char (1- (point))))
+              ;; Do not do anything if there's already a gravatar.  This can
+              ;; happen if the buffer has been regenerated in the mean time, for
+              ;; example we were fetching someaddress, and then we change to
+              ;; another mail with the same someaddress.
+              (unless (get-text-property (point) 'gnus-gravatar)
+                (let ((pos (point)))
+                  (setq gravatar (append gravatar gnus-gravatar-properties))
+                  (gnus-put-image gravatar (buffer-substring pos (1+ pos)) category)
+                  (put-text-property pos (point) 'gnus-gravatar address)
+                  (gnus-add-wash-type category)
+                  (gnus-add-image category gravatar)))))
+          (goto-char mark))))))
 
 ;;;###autoload
 (defun gnus-treat-from-gravatar (&optional force)
   "Display gravatar in the From header.
 If gravatar is already displayed, remove it."
-  (interactive (list t)) ;; When type `W D g'
+  (interactive "p")
   (gnus-with-article-buffer
     (if (memq 'from-gravatar gnus-article-wash-types)
         (gnus-delete-images 'from-gravatar)
@@ -133,12 +136,12 @@ If gravatar is already displayed, remove it."
 (defun gnus-treat-mail-gravatar (&optional force)
   "Display gravatars in the Cc and To headers.
 If gravatars are already displayed, remove them."
-  (interactive (list t)) ;; When type `W D h'
-    (gnus-with-article-buffer
-      (if (memq 'mail-gravatar gnus-article-wash-types)
-          (gnus-delete-images 'mail-gravatar)
-        (gnus-gravatar-transform-address "cc" 'mail-gravatar force)
-        (gnus-gravatar-transform-address "to" 'mail-gravatar force))))
+  (interactive "p")
+  (gnus-with-article-buffer
+    (if (memq 'mail-gravatar gnus-article-wash-types)
+        (gnus-delete-images 'mail-gravatar)
+      (gnus-gravatar-transform-address "cc" 'mail-gravatar force)
+      (gnus-gravatar-transform-address "to" 'mail-gravatar force))))
 
 (provide 'gnus-gravatar)
 
diff --git a/lisp/image/gravatar.el b/lisp/image/gravatar.el
index 9a1ec3b556b..ea746b71d7b 100644
--- a/lisp/image/gravatar.el
+++ b/lisp/image/gravatar.el
@@ -1,9 +1,9 @@
-;;; gravatar.el --- Get Gravatars
+;;; gravatar.el --- Get Gravatars -*- lexical-binding: t -*-
 
 ;; Copyright (C) 2010-2019 Free Software Foundation, Inc.
 
 ;; Author: Julien Danjou <julien@danjou.info>
-;; Keywords: news
+;; Keywords: comm, multimedia
 
 ;; This file is part of GNU Emacs.
 
@@ -26,10 +26,9 @@
 
 (require 'url)
 (require 'url-cache)
-(require 'image)
 
 (defgroup gravatar nil
-  "Gravatar."
+  "Gravatars."
   :version "24.1"
   :group 'comm)
 
@@ -88,22 +87,13 @@ Valid sizes range from 1 to 2048 inclusive."
           gravatar-rating
           gravatar-size))
 
-(defun gravatar-cache-expired (url)
-  "Check if URL is cached for more than `gravatar-cache-ttl'."
-  (cond (url-standalone-mode
-         (not (file-exists-p (url-cache-create-filename url))))
-        (t (let ((cache-time (url-is-cached url)))
-             (if cache-time
-                 (time-less-p (time-add cache-time gravatar-cache-ttl) nil)
-               t)))))
-
 (defun gravatar-get-data ()
-  "Get data from current buffer."
+  "Return body of current URL buffer, or nil on failure."
   (save-excursion
     (goto-char (point-min))
-    (when (re-search-forward "^HTTP/.+ 200 OK$" nil (line-end-position))
-      (when (search-forward "\n\n" nil t)
-        (buffer-substring (point) (point-max))))))
+    (and (re-search-forward "^HTTP/.+ 200 OK$" nil (line-end-position))
+         (search-forward "\n\n" nil t)
+         (buffer-substring (point) (point-max)))))
 
 (defun gravatar-data->image ()
   "Get data of current buffer and return an image.
@@ -113,29 +103,20 @@ If no image available, return 'error."
         (create-image data nil t)
       'error)))
 
-(autoload 'help-function-arglist "help-fns")
-
 ;;;###autoload
-(defun gravatar-retrieve (mail-address cb &optional cbargs)
+(defun gravatar-retrieve (mail-address callback &optional cbargs)
   "Asynchronously retrieve a gravatar for MAIL-ADDRESS.
-When finished, call CB as (apply CB GRAVATAR CBARGS),
+When finished, call CALLBACK as (apply CALLBACK GRAVATAR CBARGS),
 where GRAVATAR is either an image descriptor, or the symbol
 `error' if the retrieval failed."
   (let ((url (gravatar-build-url mail-address)))
-    (if (gravatar-cache-expired url)
-        (let ((args (list url
-                          'gravatar-retrieved
-                          (list cb (when cbargs cbargs)))))
-          (when (> (length (help-function-arglist 'url-retrieve))
-                   4)
-            (setq args (nconc args (list t))))
-          (apply #'url-retrieve args))
-      (apply cb
-               (with-temp-buffer
-                 (set-buffer-multibyte nil)
-                 (url-cache-extract (url-cache-create-filename url))
-                 (gravatar-data->image))
-               cbargs))))
+    (if (url-cache-expired url gravatar-cache-ttl)
+        (url-retrieve url #'gravatar-retrieved (list callback cbargs) t)
+      (apply callback
+             (with-temp-buffer
+               (url-cache-extract (url-cache-create-filename url))
+               (gravatar-data->image))
+             cbargs))))
 
 ;;;###autoload
 (defun gravatar-retrieve-synchronously (mail-address)
@@ -143,19 +124,16 @@ where GRAVATAR is either an image descriptor, or the symbol
 Value is either an image descriptor, or the symbol `error' if the
 retrieval failed."
   (let ((url (gravatar-build-url mail-address)))
-    (if (gravatar-cache-expired url)
+    (if (url-cache-expired url gravatar-cache-ttl)
         (with-current-buffer (url-retrieve-synchronously url)
           (when gravatar-automatic-caching
             (url-store-in-cache (current-buffer)))
-          (let ((data (gravatar-data->image)))
-            (kill-buffer (current-buffer))
-            data))
+          (prog1 (gravatar-data->image)
+            (kill-buffer (current-buffer))))
       (with-temp-buffer
-        (set-buffer-multibyte nil)
         (url-cache-extract (url-cache-create-filename url))
         (gravatar-data->image)))))
 
-
 (defun gravatar-retrieved (status cb &optional cbargs)
   "Callback function used by `gravatar-retrieve'."
   ;; Store gravatar?