bug#23412: 25.1.50; GUI Emacs on Mac OS X: text is keeping shaking/re-displaying when insert text with external input method

[Alan Third <alan@idiocy.org>]

[-- Attachment #1: Type: text/plain, Size: 1185 bytes --]

On Tue, Oct 29, 2019 at 01:24:11PM +0000, HaiJun Zhang wrote:
> I tried the patch. It works well for almost all the use cases except the following one:
> Press ESC to cancel the input. The working text will not be cleared
> as before. It will be cleared after inputting another char or
> pressing ENTER.

That makes sense. It looks like there is no explicit clear from the
toolkit.

> I think there are cases like the above when only
> ’ns-unput-working-text is fired without following
> ’ns-put-working-text.
> 
> In my modified ns-unput-working-text, it processes these cases. If
> the new working text is the same as the old one, then there will be
> no following ’ns-put-working-text and it clears the working text.
> Maybe the checking can be done in C?

I think in C we can get away with just checking whether the new text
is empty. If there is any text at all then replacing the working text
seems to do the right thing, even if the new text is shorter than the
old. I could be wrong, though, I’ve never really used these input
methods so don’t know if there are things I’m not testing.

New patch attached, please try it and let me know how it goes.
-- 
Alan Third

[-- Attachment #2: 0001-Prevent-text-flicker-with-macOS-input-methods-bug-23.patch --]
[-- Type: text/plain, Size: 1087 bytes --]

From dd965985108e36ab3e559834963765a23a44ca2b Mon Sep 17 00:00:00 2001
From: Alan Third <alan@idiocy.org>
Date: Mon, 28 Oct 2019 11:21:29 +0000
Subject: [PATCH] Prevent text flicker with macOS input methods (bug#23412)

* src/nsterm.m ([EmacsView setMarkedText:selectedRange:]): Don't
always delete the working text as ns-put-working-text does that.
---
 src/nsterm.m | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/nsterm.m b/src/nsterm.m
index 5583c6105c..afe7069aae 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -6435,15 +6435,17 @@ - (void)setMarkedText: (id)aString selectedRange: (NSRange)selRange
            (unsigned long)selRange.length,
            (unsigned long)selRange.location);
 
-  if (workingText != nil)
-    [self deleteWorkingText];
   if ([str length] == 0)
-    return;
+    {
+      [self deleteWorkingText];
+      return;
+    }
 
   if (!emacs_event)
     return;
 
   processingCompose = YES;
+  [workingText release];
   workingText = [str copy];
   ns_working_text = build_string ([workingText UTF8String]);
 
-- 
2.21.0