From e2aa2a2048ceaf2bf570e8785520b3e764bdb0b7 Mon Sep 17 00:00:00 2001
From: ed <eddavies95@gmail.com>
Date: Mon, 7 Jun 2021 16:52:51 +0100
Subject: [PATCH] Accessibility:  Throttle TreeView/ListBox Viewport move
 AccessibilityEvent::structureChanged notifications

---
 modules/juce_gui_basics/widgets/juce_ListBox.cpp | 14 +++++++++++---
 .../juce_gui_basics/widgets/juce_TreeView.cpp    | 16 ++++++++++++----
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/modules/juce_gui_basics/widgets/juce_ListBox.cpp b/modules/juce_gui_basics/widgets/juce_ListBox.cpp
index 6da89672e4..06c01a228e 100644
--- a/modules/juce_gui_basics/widgets/juce_ListBox.cpp
+++ b/modules/juce_gui_basics/widgets/juce_ListBox.cpp
@@ -274,7 +274,8 @@ public:
 
 
 //==============================================================================
-class ListBox::ListViewport  : public Viewport
+class ListBox::ListViewport  : public Viewport,
+                               private Timer
 {
 public:
     ListViewport (ListBox& lb)  : owner (lb)
@@ -319,8 +320,7 @@ public:
         if (auto* m = owner.getModel())
             m->listWasScrolled();
 
-        if (auto* handler = owner.getAccessibilityHandler())
-            handler->notifyAccessibilityEvent (AccessibilityEvent::structureChanged);
+        startTimer (50);
     }
 
     void updateVisibleArea (const bool makeSureItUpdatesContent)
@@ -456,6 +456,14 @@ public:
     }
 
 private:
+    void timerCallback() override
+    {
+        stopTimer();
+
+        if (auto* handler = owner.getAccessibilityHandler())
+            handler->notifyAccessibilityEvent (AccessibilityEvent::structureChanged);
+    }
+
     ListBox& owner;
     OwnedArray<RowComponent> rows;
     int firstIndex = 0, firstWholeIndex = 0, lastWholeIndex = 0;
diff --git a/modules/juce_gui_basics/widgets/juce_TreeView.cpp b/modules/juce_gui_basics/widgets/juce_TreeView.cpp
index 266123c227..54949d2f0a 100644
--- a/modules/juce_gui_basics/widgets/juce_TreeView.cpp
+++ b/modules/juce_gui_basics/widgets/juce_TreeView.cpp
@@ -621,7 +621,8 @@ private:
 };
 
 //==============================================================================
-class TreeView::TreeViewport  : public Viewport
+class TreeView::TreeViewport  : public Viewport,
+                                private Timer
 {
 public:
     TreeViewport() = default;
@@ -645,9 +646,7 @@ public:
         lastX = newVisibleArea.getX();
         updateComponents (hasScrolledSideways);
 
-        if (auto* tree = getParentComponent())
-            if (auto* handler = tree->getAccessibilityHandler())
-                handler->notifyAccessibilityEvent (AccessibilityEvent::structureChanged);
+        startTimer (50);
     }
 
     ContentComponent* getContentComp() const noexcept
@@ -665,6 +664,15 @@ public:
     }
 
 private:
+    void timerCallback() override
+    {
+        stopTimer();
+
+        if (auto* tree = getParentComponent())
+            if (auto* handler = tree->getAccessibilityHandler())
+                handler->notifyAccessibilityEvent (AccessibilityEvent::structureChanged);
+    }
+
     int lastX = -1;
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (TreeViewport)