Reduce CursorChanged Events for Accessibility (#5196)

## Summary of the Pull Request Reduce the number of times we dispatch a cursor changed event. We were firing it every time the renderer had to do anything related to the cursor. Unfortunately, blinking the cursor triggered this behavior. Now we just check if the position has changed. ## PR Checklist * [X] Closes #5143 ## Validation Steps Performed Verified using Narrator Also verified #3791 still works right
microsoft · Apr 1, 2020 · f8227e6 · f8227e6 · github-actions · Apr 1, 2020
1 parent 8585bc6
commit f8227e6
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Showing 2 changed files with 14 additions and 5 deletions.
diff --git a/src/renderer/uia/UiaRenderer.cpp b/src/renderer/uia/UiaRenderer.cpp
@@ -68,12 +68,21 @@ UiaEngine::UiaEngine(IUiaEventDispatcher* dispatcher) :
 // Arguments:
 // - pcoordCursor - the new position of the cursor
 // Return Value:
-// - S_FALSE
-[[nodiscard]] HRESULT UiaEngine::InvalidateCursor(const COORD* const /*pcoordCursor*/) noexcept
+// - S_OK
+[[nodiscard]] HRESULT UiaEngine::InvalidateCursor(const COORD* const pcoordCursor) noexcept
+try
 {
-    _cursorChanged = true;
-    return S_FALSE;
+    RETURN_HR_IF_NULL(E_INVALIDARG, pcoordCursor);
+
+    // check if cursor moved
+    if (*pcoordCursor != _prevCursorPos)
+    {
+        _prevCursorPos = *pcoordCursor;
+        _cursorChanged = true;
+    }
+    return S_OK;
 }
+CATCH_RETURN();
 
 // Routine Description:
 // - Invalidates a rectangle describing a pixel area on the display
@@ -246,7 +255,6 @@ UiaEngine::UiaEngine(IUiaEventDispatcher* dispatcher) :
     _selectionChanged = false;
     _textBufferChanged = false;
     _cursorChanged = false;
-    _prevSelection.clear();
     _isPainting = false;
 
     return S_OK;

diff --git a/src/renderer/uia/UiaRenderer.hpp b/src/renderer/uia/UiaRenderer.hpp
@@ -88,5 +88,6 @@ namespace Microsoft::Console::Render
         Microsoft::Console::Types::IUiaEventDispatcher* _dispatcher;
 
         std::vector<SMALL_RECT> _prevSelection;
+        til::point _prevCursorPos;
     };
 }