Best practice for changing cursor in ArcGIS Pro MapTool without lag

rdc_hirohara — Fri, 27 Mar 2026 05:31:55 GMT

Hello,

I am developing an ArcGIS Pro SDK MapTool in C#.

I want to change the mouse cursor depending on whether the current mouse position is on a selected polygon feature or not.
For example:

show `Hand` when the mouse is on the selected feature
show `Cross` otherwise

At first, I implemented the check inside `OnToolMouseMove` using `QueuedTask.Run`, something like:

protected override void OnToolMouseMove(MapViewMouseEventArgs args) { _ = QueuedTask.Run(() => { var mapPoint = MapView.Active.ClientToMap(args.ClientPoint); bool isHit = GeometryEngine.Instance.Intersects(_selectedGeometry, mapPoint); Cursor = isHit ? Cursors.Hand : Cursors.Cross; }); base.OnToolMouseMove(args); }

However, this caused noticeable lag.
It looks like `QueuedTask` calls keep getting queued during mouse movement, and cursor updates become delayed.

I improved the behavior by preventing multiple simultaneous cursor checks and only processing the latest mouse position, but I still have these questions:

Is there any official or recommended best practice for changing the cursor dynamically in a `MapTool` based on mouse position?
Is there any way to avoid `ClientToMap` on every mouse move while still keeping correct hit-testing?
Is the default `MapTool` cursor documented anywhere?I am currently using `Cursors.Cross` as the non-hit cursor, but I am not sure whether that matches ArcGIS Pro’s default tool cursor.
More generally, what is the recommended pattern for high-frequency mouse-move processing in a `MapTool` when MCT access is required?

For context, the selected geometry may sometimes include multiple polygons, and possibly polygons with holes, so replacing the hit-test with a very rough custom approximation is not always ideal.

If anyone has sample code, recommendations, or experience with this kind of cursor handling, I would appreciate it.

Thank you.

Re: Best practice for changing cursor in ArcGIS Pro MapTool without lag

sjones_esriau — Mon, 30 Mar 2026 09:33:43 GMT

Hey there,

Traditional OnToolMouseMove tricks wont work here but you can use some Task secret sauce (TaskCompletionSource).

private Geometry _firstSelectedGeometry = null; private TaskCompletionSource<MapPoint> _tcs; private System.Windows.Point _lastClientPoint; private bool _processing = false; protected override void OnToolMouseMove(MapViewMouseEventArgs args) { _lastClientPoint = args.ClientPoint; // If a conversion is already in progress, don't start another if (_processing) return; _processing = true; _tcs = new TaskCompletionSource<MapPoint>(); QueuedTask.Run(() => { var mapPoint = MapView.Active.ClientToMap(args.ClientPoint); _tcs.TrySetResult(mapPoint); }); // Continue on UI thread when MCT finishes _ = HandleMapPointAsync(); base.OnToolMouseMove(args); } private async Task HandleMapPointAsync() { try { var mapPoint = await _tcs.Task; bool isHit = GeometryEngine.Instance.Intersects(_firstSelectedGeometry, mapPoint); Cursor = isHit ? Cursors.Hand : Cursors.Cross; } finally { _processing = false; } }

Why this works

Only one ClientToMap is ever queued.
Latest mouse position always wins.

If you have complex geometry you could still do a pre-hit test with the evelope (.Contains) but this may not be required.

Ps. This is not definitive Esri code....

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Best practice for changing cursor in ArcGIS Pro MapTool without lag

Re: Best practice for changing cursor in ArcGIS Pro MapTool without lag