bug#22465: xwidget-webkit-scroll-behaviour = image is non-functional

bug#22465: xwidget-webkit-scroll-behaviour = image is non-functional

[Glenn Morris]

Package: emacs
Version: 25.0.50

When xwidget-webkit-scroll-behavior = image, the functions
xwidget-webkit-scroll-forward and xwidget-webkit-scroll-backward are
obviously broken (they just call themselves recursively forever).

bug#22465: xwidget-webkit-scroll-behaviour = image is non-functional

[Paul Eggert]

[-- Attachment #1: Type: text/plain, Size: 81 bytes --]

Attached is a proposed patch for this bug. It is not fancy, but it works for me.

[-- Attachment #2: 0001-Fix-xwidget-webkit-scroll-forward-infloop.fix --]
[-- Type: text/plain, Size: 1395 bytes --]

From 879895ad058294eb49d8372ef5dbf053973e45b9 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 5 May 2016 22:44:16 -0700
Subject: [PATCH] Fix xwidget-webkit-scroll-forward infloop
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* lisp/xwidget.el (xwidget-webkit-scroll-forward)
(xwidget-webkit-scroll-backward): Don’t loop if
xwidget-webkit-scroll-behavior’s value is ‘image’ (Bug#22465).
---
 lisp/xwidget.el | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lisp/xwidget.el b/lisp/xwidget.el
index 19f631f..d64237a 100644
--- a/lisp/xwidget.el
+++ b/lisp/xwidget.el
@@ -165,7 +165,7 @@ xwidget-webkit-scroll-forward
   (interactive)
   (if (eq xwidget-webkit-scroll-behavior 'native)
       (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t 50)
-    (xwidget-webkit-scroll-forward)))   ; FIXME infloop!
+    (image-forward-hscroll 5)))
 
 (defun xwidget-webkit-scroll-backward ()
   "Scroll webkit backwards.
@@ -174,7 +174,7 @@ xwidget-webkit-scroll-backward
   (interactive)
   (if (eq xwidget-webkit-scroll-behavior 'native)
       (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t -50)
-    (xwidget-webkit-scroll-backward))) ; FIXME infloop!
+    (image-backward-hscroll 5)))
 
 
 ;; The xwidget event needs to go into a higher level handler
-- 
2.7.4

bug#22465: xwidget-webkit-scroll-behaviour = image is non-functional

[Glenn Morris]

Paul Eggert wrote:

> Attached is a proposed patch for this bug. It is not fancy, but it
> works for me.

Thanks. I wonder if the 'image scrolling method should simply be
removed, since it doesn't work (to date) and isn't the default.
Are two methods really needed/useful?

> From 879895ad058294eb49d8372ef5dbf053973e45b9 Mon Sep 17 00:00:00 2001
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Thu, 5 May 2016 22:44:16 -0700
> Subject: [PATCH] Fix xwidget-webkit-scroll-forward infloop
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
>
> * lisp/xwidget.el (xwidget-webkit-scroll-forward)
> (xwidget-webkit-scroll-backward): Don't loop if
> xwidget-webkit-scroll-behavior's value is 'image' (Bug#22465).
> ---
>  lisp/xwidget.el | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/lisp/xwidget.el b/lisp/xwidget.el
> index 19f631f..d64237a 100644
> --- a/lisp/xwidget.el
> +++ b/lisp/xwidget.el
> @@ -165,7 +165,7 @@ xwidget-webkit-scroll-forward
>    (interactive)
>    (if (eq xwidget-webkit-scroll-behavior 'native)
>        (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t 50)
> -    (xwidget-webkit-scroll-forward)))   ; FIXME infloop!
> +    (image-forward-hscroll 5)))
>  
>  (defun xwidget-webkit-scroll-backward ()
>    "Scroll webkit backwards.
> @@ -174,7 +174,7 @@ xwidget-webkit-scroll-backward
>    (interactive)
>    (if (eq xwidget-webkit-scroll-behavior 'native)
>        (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t -50)
> -    (xwidget-webkit-scroll-backward))) ; FIXME infloop!
> +    (image-backward-hscroll 5)))
>  
>  
>  ;; The xwidget event needs to go into a higher level handler

bug#22465: xwidget-webkit-scroll-behaviour = image is non-functional

[joakim]

Glenn Morris <rgm@gnu.org> writes:

> Paul Eggert wrote:
>
>> Attached is a proposed patch for this bug. It is not fancy, but it
>> works for me.
>
> Thanks. I wonder if the 'image scrolling method should simply be
> removed, since it doesn't work (to date) and isn't the default.
> Are two methods really needed/useful?

Short version:

It is probably just as well to remove the 'image method.

Long version:

The 'image method was the original scrolling method, which simply makes
a large xwidget and scrolls it using the same method as emacs uses to
scroll images. I liked this method because it was consistent with other
Emacs scrolling.

The 'native method lets webkit do the scrolling.

Originally I used the 'image method myself and added the 'native method
because users wanted it. Now I never use 'image, only 'native.

Perhaps someone still prefers the 'image method though.



>
>> From 879895ad058294eb49d8372ef5dbf053973e45b9 Mon Sep 17 00:00:00 2001
>> From: Paul Eggert <eggert@cs.ucla.edu>
>> Date: Thu, 5 May 2016 22:44:16 -0700
>> Subject: [PATCH] Fix xwidget-webkit-scroll-forward infloop
>> MIME-Version: 1.0
>> Content-Type: text/plain; charset=UTF-8
>> Content-Transfer-Encoding: 8bit
>>
>> * lisp/xwidget.el (xwidget-webkit-scroll-forward)
>> (xwidget-webkit-scroll-backward): Don't loop if
>> xwidget-webkit-scroll-behavior's value is 'image' (Bug#22465).
>> ---
>>  lisp/xwidget.el | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/lisp/xwidget.el b/lisp/xwidget.el
>> index 19f631f..d64237a 100644
>> --- a/lisp/xwidget.el
>> +++ b/lisp/xwidget.el
>> @@ -165,7 +165,7 @@ xwidget-webkit-scroll-forward
>>    (interactive)
>>    (if (eq xwidget-webkit-scroll-behavior 'native)
>>        (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t 50)
>> -    (xwidget-webkit-scroll-forward)))   ; FIXME infloop!
>> +    (image-forward-hscroll 5)))
>>  
>>  (defun xwidget-webkit-scroll-backward ()
>>    "Scroll webkit backwards.
>> @@ -174,7 +174,7 @@ xwidget-webkit-scroll-backward
>>    (interactive)
>>    (if (eq xwidget-webkit-scroll-behavior 'native)
>>        (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t -50)
>> -    (xwidget-webkit-scroll-backward))) ; FIXME infloop!
>> +    (image-backward-hscroll 5)))
>>  
>>  
>>  ;; The xwidget event needs to go into a higher level handler

-- 
Joakim Verona

bug#22465: xwidget-webkit-scroll-behaviour = image is non-functional

[Paul Eggert]

[-- Attachment #1: Type: text/plain, Size: 347 bytes --]

joakim@verona.se wrote:
> Perhaps someone still prefers the 'image method though.

This seems unlikely, given that it recurses infinitely whenever it scrolls left
or right. Anyway, thanks for following up. If nobody objects I would like to
install the attached patch to emacs-25 to remove xwidget-webkit-scroll-behavior
and therefore fix the bug.

[-- Attachment #2: 0001-Remove-buggy-non-native-image-scrolling.patch --]
[-- Type: text/x-diff, Size: 3749 bytes --]

From 58b7ecc4bcba46c775a7edca209587f034185861 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sat, 7 May 2016 17:17:55 -0700
Subject: [PATCH] Remove buggy non-native image scrolling

This never worked, and could cause infinite recursion.
Problem reported by Glenn Morris (Bug#22465).
* lisp/xwidget.el (xwidget-webkit-scroll-behavior): Remove.
All uses removed.
---
 lisp/xwidget.el | 43 +++++++++----------------------------------
 1 file changed, 9 insertions(+), 34 deletions(-)

diff --git a/lisp/xwidget.el b/lisp/xwidget.el
index 19f631f..7a0ca8b 100644
--- a/lisp/xwidget.el
+++ b/lisp/xwidget.el
@@ -34,13 +34,6 @@
 (require 'cl-lib)
 (require 'bookmark)
 
-(defcustom xwidget-webkit-scroll-behavior 'native
-  "Scrolling behavior of the webkit instance.
-The possible values are: `native' or `image'."
-  :version "25.1"
-  :group 'frames   ; TODO add xwidgets group if more options are added
-  :type '(choice (const native) (const image)))
-
 (declare-function make-xwidget "xwidget.c"
                   (type title width height arguments &optional buffer))
 (declare-function xwidget-set-adjustment "xwidget.c"
@@ -141,40 +134,24 @@ xwidget-webkit-mode-map
   "Keymap for `xwidget-webkit-mode'.")
 
 (defun xwidget-webkit-scroll-up ()
-  "Scroll webkit up.
-Depending on the value of `xwidget-webkit-scroll-behavior',
-this scrolls in `native' fashion, or like `image-mode' would."
+  "Scroll webkit up."
   (interactive)
-  (if (eq xwidget-webkit-scroll-behavior 'native)
-      (xwidget-set-adjustment (xwidget-webkit-last-session) 'vertical t 50)
-    (image-scroll-up)))
+  (xwidget-set-adjustment (xwidget-webkit-last-session) 'vertical t 50))
 
 (defun xwidget-webkit-scroll-down ()
-  "Scroll webkit down.
-Depending on the value of `xwidget-webkit-scroll-behavior',
-this scrolls in `native' fashion, or like `image-mode' would."
+  "Scroll webkit down."
   (interactive)
-  (if (eq xwidget-webkit-scroll-behavior 'native)
-      (xwidget-set-adjustment (xwidget-webkit-last-session) 'vertical t -50)
-    (image-scroll-down)))
+  (xwidget-set-adjustment (xwidget-webkit-last-session) 'vertical t -50))
 
 (defun xwidget-webkit-scroll-forward ()
-  "Scroll webkit forwards.
-Depending on the value of `xwidget-webkit-scroll-behavior',
-this scrolls in `native' fashion, or like `image-mode' would."
+  "Scroll webkit forwards."
   (interactive)
-  (if (eq xwidget-webkit-scroll-behavior 'native)
-      (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t 50)
-    (xwidget-webkit-scroll-forward)))   ; FIXME infloop!
+  (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t 50))
 
 (defun xwidget-webkit-scroll-backward ()
-  "Scroll webkit backwards.
-Depending on the value of `xwidget-webkit-scroll-behavior',
-this scrolls in `native' fashion, or like `image-mode' would."
+  "Scroll webkit backwards."
   (interactive)
-  (if (eq xwidget-webkit-scroll-behavior 'native)
-      (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t -50)
-    (xwidget-webkit-scroll-backward))) ; FIXME infloop!
+  (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t -50))
 
 
 ;; The xwidget event needs to go into a higher level handler
@@ -417,9 +394,7 @@ xwidget-webkit-adjust-size-to-content
 (defun xwidget-webkit-adjust-size-dispatch ()
   "Adjust size according to mode."
   (interactive)
-  (if (eq xwidget-webkit-scroll-behavior 'native)
-      (xwidget-webkit-adjust-size-to-window)
-    (xwidget-webkit-adjust-size-to-content))
+  (xwidget-webkit-adjust-size-to-window)
   ;; The recenter is intended to correct a visual glitch.
   ;; It errors out if the buffer isn't visible, but then we don't get
   ;; the glitch, so silence errors.
-- 
2.7.4

bug#22465: xwidget-webkit-scroll-behaviour = image is non-functional

[joakim]

Paul Eggert <eggert@cs.ucla.edu> writes:

> joakim@verona.se wrote:
>> Perhaps someone still prefers the 'image method though.
>
> This seems unlikely, given that it recurses infinitely whenever it scrolls left
> or right. Anyway, thanks for following up. If nobody objects I would like to
> install the attached patch to emacs-25 to remove xwidget-webkit-scroll-behavior
> and therefore fix the bug.

I agree, please install this fix.

>
> From 58b7ecc4bcba46c775a7edca209587f034185861 Mon Sep 17 00:00:00 2001
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Sat, 7 May 2016 17:17:55 -0700
> Subject: [PATCH] Remove buggy non-native image scrolling
>
> This never worked, and could cause infinite recursion.
> Problem reported by Glenn Morris (Bug#22465).
> * lisp/xwidget.el (xwidget-webkit-scroll-behavior): Remove.
> All uses removed.
> ---
>  lisp/xwidget.el | 43 +++++++++----------------------------------
>  1 file changed, 9 insertions(+), 34 deletions(-)
>
> diff --git a/lisp/xwidget.el b/lisp/xwidget.el
> index 19f631f..7a0ca8b 100644
> --- a/lisp/xwidget.el
> +++ b/lisp/xwidget.el
> @@ -34,13 +34,6 @@
>  (require 'cl-lib)
>  (require 'bookmark)
>  
> -(defcustom xwidget-webkit-scroll-behavior 'native
> -  "Scrolling behavior of the webkit instance.
> -The possible values are: `native' or `image'."
> -  :version "25.1"
> -  :group 'frames   ; TODO add xwidgets group if more options are added
> -  :type '(choice (const native) (const image)))
> -
>  (declare-function make-xwidget "xwidget.c"
>                    (type title width height arguments &optional buffer))
>  (declare-function xwidget-set-adjustment "xwidget.c"
> @@ -141,40 +134,24 @@ xwidget-webkit-mode-map
>    "Keymap for `xwidget-webkit-mode'.")
>  
>  (defun xwidget-webkit-scroll-up ()
> -  "Scroll webkit up.
> -Depending on the value of `xwidget-webkit-scroll-behavior',
> -this scrolls in `native' fashion, or like `image-mode' would."
> +  "Scroll webkit up."
>    (interactive)
> -  (if (eq xwidget-webkit-scroll-behavior 'native)
> -      (xwidget-set-adjustment (xwidget-webkit-last-session) 'vertical t 50)
> -    (image-scroll-up)))
> +  (xwidget-set-adjustment (xwidget-webkit-last-session) 'vertical t 50))
>  
>  (defun xwidget-webkit-scroll-down ()
> -  "Scroll webkit down.
> -Depending on the value of `xwidget-webkit-scroll-behavior',
> -this scrolls in `native' fashion, or like `image-mode' would."
> +  "Scroll webkit down."
>    (interactive)
> -  (if (eq xwidget-webkit-scroll-behavior 'native)
> -      (xwidget-set-adjustment (xwidget-webkit-last-session) 'vertical t -50)
> -    (image-scroll-down)))
> +  (xwidget-set-adjustment (xwidget-webkit-last-session) 'vertical t -50))
>  
>  (defun xwidget-webkit-scroll-forward ()
> -  "Scroll webkit forwards.
> -Depending on the value of `xwidget-webkit-scroll-behavior',
> -this scrolls in `native' fashion, or like `image-mode' would."
> +  "Scroll webkit forwards."
>    (interactive)
> -  (if (eq xwidget-webkit-scroll-behavior 'native)
> -      (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t 50)
> -    (xwidget-webkit-scroll-forward)))   ; FIXME infloop!
> +  (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t 50))
>  
>  (defun xwidget-webkit-scroll-backward ()
> -  "Scroll webkit backwards.
> -Depending on the value of `xwidget-webkit-scroll-behavior',
> -this scrolls in `native' fashion, or like `image-mode' would."
> +  "Scroll webkit backwards."
>    (interactive)
> -  (if (eq xwidget-webkit-scroll-behavior 'native)
> -      (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t -50)
> -    (xwidget-webkit-scroll-backward))) ; FIXME infloop!
> +  (xwidget-set-adjustment (xwidget-webkit-last-session) 'horizontal t -50))
>  
>  
>  ;; The xwidget event needs to go into a higher level handler
> @@ -417,9 +394,7 @@ xwidget-webkit-adjust-size-to-content
>  (defun xwidget-webkit-adjust-size-dispatch ()
>    "Adjust size according to mode."
>    (interactive)
> -  (if (eq xwidget-webkit-scroll-behavior 'native)
> -      (xwidget-webkit-adjust-size-to-window)
> -    (xwidget-webkit-adjust-size-to-content))
> +  (xwidget-webkit-adjust-size-to-window)
>    ;; The recenter is intended to correct a visual glitch.
>    ;; It errors out if the buffer isn't visible, but then we don't get
>    ;; the glitch, so silence errors.

-- 
Joakim Verona

bug#22465: xwidget-webkit-scroll-behaviour = image is non-functional

[Paul Eggert]

On 05/13/2016 01:05 AM, joakim@verona.se wrote:
> I agree, please install this fix.

Thanks, installed, and closing the bug.