From 81e7c10a73d887161afd1e6d96af5861bba6ed2b Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Wed, 27 Oct 2021 15:40:20 +0300
Subject: [PATCH] Emit DataOfferInterface::dragAndDropActionsChanged() only if
 dnd actions change

With some apps, firefox specifically, it's possible to enter a dnd
positive feedback loop, e.g.

* kwin sends wl_data_offer::action event
* the app reacts to it and calls wl_data_offer::set_actions() with the
  same actions
* kwin re-sends the wl_data_offer::action event because
  DataOfferInterface::dragAndDropActionsChanged() has been emitted
* the app calls wl_data_offer::set_actions() again, and so on...

This should make D&D in Firefox more responsive.
---
 src/wayland/dataoffer_interface.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/wayland/dataoffer_interface.cpp b/src/wayland/dataoffer_interface.cpp
index ce9db22398..ed68217251 100644
--- a/src/wayland/dataoffer_interface.cpp
+++ b/src/wayland/dataoffer_interface.cpp
@@ -119,9 +119,11 @@ void DataOfferInterfacePrivate::data_offer_set_actions(Resource *resource, uint3
         preferredAction = DataDeviceManagerInterface::DnDAction::Ask;
     }
 
-    supportedDnDActions = supportedActions;
-    preferredDnDAction = preferredAction;
-    Q_EMIT q->dragAndDropActionsChanged();
+    if (supportedDnDActions != supportedActions || preferredDnDAction != preferredAction) {
+        supportedDnDActions = supportedActions;
+        preferredDnDAction = preferredAction;
+        Q_EMIT q->dragAndDropActionsChanged();
+    }
 }
 
 void DataOfferInterface::sendSourceActions()