From d2c61d57357406490cde305725518a5c30b96a65 Mon Sep 17 00:00:00 2001
From: Monica Kozbial <6621618+moniika@users.noreply.github.com>
Date: Wed, 9 Jun 2021 19:20:47 -0700
Subject: [PATCH] Prevent uncessary add/remove class calls on cursor during
 drag (#4885)

---
 core/block_dragger.js  |  9 ++++++---
 core/bubble_dragger.js | 14 +++++++-------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/core/block_dragger.js b/core/block_dragger.js
index c9c477430..8dfac6542 100644
--- a/core/block_dragger.js
+++ b/core/block_dragger.js
@@ -217,9 +217,12 @@ Blockly.BlockDragger.prototype.dragBlock = function(e, currentDragDeltaXY) {
   }
 
   this.draggedConnectionManager_.update(delta, this.dragTarget_);
-  this.wouldDeleteBlock_ = this.draggedConnectionManager_.wouldDeleteBlock();
-
-  this.updateCursorDuringBlockDrag_();
+  var wouldDeleteBlock = this.draggedConnectionManager_.wouldDeleteBlock();
+  if (wouldDeleteBlock != this.wouldDeleteBlock_) {
+    // Prevent unnecessary add/remove class calls.
+    this.updateCursorDuringBlockDrag_();
+  }
+  this.wouldDeleteBlock_ = wouldDeleteBlock;
 };
 
 /**
diff --git a/core/bubble_dragger.js b/core/bubble_dragger.js
index 38c339158..2112eb3ab 100644
--- a/core/bubble_dragger.js
+++ b/core/bubble_dragger.js
@@ -140,9 +140,13 @@ Blockly.BubbleDragger.prototype.dragBubble = function(e, currentDragDeltaXY) {
     oldDragTarget && oldDragTarget.onDragExit();
     this.dragTarget_ && this.dragTarget_.onDragEnter();
   }
-  this.wouldDeleteBubble_ = this.shouldDelete_(this.dragTarget_);
 
-  this.updateCursorDuringBubbleDrag_();
+  var wouldDeleteBubble = this.shouldDelete_(this.dragTarget_);
+  if (wouldDeleteBubble != this.wouldDeleteBubble_) {
+    // Prevent unnecessary add/remove class calls.
+    this.updateCursorDuringBubbleDrag_();
+  }
+  this.wouldDeleteBubble_ = wouldDeleteBubble;
 };
 
 /**
@@ -177,11 +181,7 @@ Blockly.BubbleDragger.prototype.shouldDelete_ = function(dragTarget) {
  * @private
  */
 Blockly.BubbleDragger.prototype.updateCursorDuringBubbleDrag_ = function() {
-  if (this.wouldDeleteBubble_) {
-    this.draggingBubble_.setDeleteStyle(true);
-  } else {
-    this.draggingBubble_.setDeleteStyle(false);
-  }
+  this.draggingBubble_.setDeleteStyle(this.wouldDeleteBubble_);
 };
 
 /**