topic Re: Buffering a click in screen space in ArcGIS Pro SDK Questions

Buffering a click in screen space

MBambino_ATS — Tue, 12 Sep 2023 15:26:09 GMT

I have a Map Tool that listens for a click on the map to then search for shapes (mainly lines and points). I already have the settings enabled to use the visual shape to increase the click area, but is it possible to extend that even further? I know that you can use a circle to increase the search area, but that makes zoomed-in clicks much wider than zoomed out clicks. Is there a way to scale the circle to the screen size, so for example, I would search and extra 4 pixels in all directions?

Re: Buffering a click in screen space

GKmieliauskas — Tue, 12 Sep 2023 15:44:12 GMT

Hi,

Look at ArcGIS Pro SDK community sample

It uses MapTool with SketchOutputMode equal SketchOutputMode.Screen.

In OnToolActivateAsync method it expands clicked point extent by 3 pixels.

Re: Buffering a click in screen space

MBambino_ATS — Tue, 12 Sep 2023 21:01:05 GMT

protected override async Task<bool> OnSketchCompleteAsync(Geometry geometry) { return await QueuedTask.Run<bool>(async () => { // geometry is a point var clickedPnt = geometry as MapPoint; if (clickedPnt == null) return false; float tolerance = 4.0f; // Buffer size // Take the screen-space point and buffer it by the tolerance var topLeft = new Coordinate2D(clickedPnt.X - tolerance, clickedPnt.Y + tolerance); var bottomRight = new Coordinate2D(clickedPnt.X + tolerance, clickedPnt.Y - tolerance); Geometry envelopeGeometry = EnvelopeBuilderEx.CreateEnvelope(topLeft, bottomRight); if (envelopeGeometry == null) return false; var result = ActiveMapView.GetFeatures(envelopeGeometry); foreach (var kvp in result.ToDictionary()){ // Do Stuff } return true; // Return T/F based on the above loop }); }

Thanks for pointing me to that!
I found a mistake in that example, though. The envelope created is never used, and if it were used, it wouldn't find the correct target due to a differing spatial reference id.
Here is the correct code:

Re: Buffering a click in screen space

Wolf — Wed, 13 Sep 2023 21:52:23 GMT

Thanks for pointing out the issue with the sample, i will correct the issue for the upcoming 3.2 release.

This code uses a circle around the click point using the pixel tolerance as the radius:

// pixel tolerance var toleranceInScreenUnits = 10; // Use bottomRight to popup the dynamic menu result bottomRight = new Point(clickedPnt.X + toleranceInScreenUnits, clickedPnt.Y + toleranceInScreenUnits); var toleranceInMapUnits = GetScreenPointsInMapUnits(toleranceInScreenUnits, MapView.Active); // Create a search circle around the click point using the pixel tolerance as a radius var pnt = MapView.Active.ClientToMap(new Point(clickedPnt.X, clickedPnt.Y)); var arcSegment = EllipticArcBuilderEx.CreateCircle(pnt.Coordinate2D, toleranceInMapUnits, ArcOrientation.ArcClockwise, pnt.SpatialReference); var circlePolygon = PolygonBuilderEx.CreatePolygon(new[] { arcSegment }); //Get the features that intersect the search circle polygon var result = ActiveMapView.GetFeatures(circlePolygon);

Here is a screenshot that show the search polygon on the map:

Re: Buffering a click in screen space

MBambino_ATS — Thu, 14 Sep 2023 12:24:33 GMT

Thank you for that!
Where does GetScreenPointsInMapUnits come from?

Re: Buffering a click in screen space

Wolf — Thu, 14 Sep 2023 22:44:02 GMT

Sorry i forgot to include the GetScreenPointsInMapUnits method in my snippet above.

private double GetScreenPointsInMapUnits (double pixels, MapView mapView) { var left = new Point(0, 0); var right = new Point(0, pixels); var pntLeft = mapView.ClientToMap(left); var pntRight = mapView.ClientToMap(right); var line = LineBuilderEx.CreateLineSegment (pntLeft, pntRight); return line.Length; }

In essence the method takes the tolerance in screen units (i.e. pixels) and returns the tolerance in units for the current active map's spatial reference. So when i generate the circle geometry for the search i can then use toleranceInMapUnits as the radius for the circle.