topic Re: Adding x and y offset to a Point in Qt Maps SDK Questions

Adding x and y offset to a Point

FatmaAkdemir — Mon, 15 Nov 2021 07:07:42 GMT

I want to obtain a new Point (geodetic) by adding x and y offset (in meters) to another Point. Is there any class or function to do that like in the case of GeodeticDistanceResult?

Re: Adding x and y offset to a Point

AndrewBladon — Mon, 15 Nov 2021 12:30:28 GMT

Hi Fatma - thank you for your message.

Yes, you can create a new point by applying an offset to an existing point using the GeometryEngine::moveGeodetic method (or GeometryEngine.moveGeodetic method using Qml). This allows you to offset a point/points by a specified distance and azimuth.

If you would like to apply an offset in the x and y directions, you could use the moveGeodetic method twice, once in the x-direction and then again in the y-direction. Please find an example of this using the C++ api below, where:

An initial point initialPoint is created.
initialPoint is converted from a Point object into a QList<Point> called initialPointList for compatability with the GeometryEngine::moveGeodetic method arguments.
initialPointList is offset by 1000m in the y-direction to create a new QList<Point> called yOffsetPoint.
yOffsetPoint is offset by 500m in the x-direction to create a new QList<Point> called offsetPointList.
The offset point is converted from the QList<Point> into a Point called offsetPoint.

// Define initial point. Point initialPoint(7.65851, 45.97661, SpatialReference::wgs84()); // Apply 1000m offset in the y-direction (i.e. azimuth = 0 deg). QList<Point> initialPointList{initialPoint}; QList<Point> yOffsetPoint = GeometryEngine::moveGeodetic(initialPointList, 1000, LinearUnit::meters(), 0.0f, AngularUnit::degrees(), GeodeticCurveType::GreatElliptic); // Apply 500m offset in the x-direction (i.e. azimuth = 90 deg). QList<Point> offsetPointList = GeometryEngine::moveGeodetic(yOffsetPoint, 500, LinearUnit::meters(), 90.0f, AngularUnit::degrees(), GeodeticCurveType::GreatElliptic); // Convert offsetPointList from QList<Point> to Point. Point offsetPoint = offsetPointList.at(0);

I hope this helps you achieve your desired result. Let us know if we can provide you with any further information.

Re: Adding x and y offset to a Point

FatmaAkdemir — Mon, 15 Nov 2021 12:38:27 GMT

Thank you very much @AndrewBladon ! I guess I have overlooked this method of GeometryEngine.

Re: Adding x and y offset to a Point

lsc — Wed, 11 Oct 2023 13:59:35 GMT

Could you give me an example using this method with Qml? I want to define a function that enables a point to be shifted 2km to the north. But the return value of the function is a empty list.

Re: Adding x and y offset to a Point

LucasDanzinger — Tue, 17 Oct 2023 14:00:05 GMT

Here is some sample code I put together that moves the point and displays a graphic at the new point

ApplicationWindow { id: appWindow width: 800 height: 600 title: "Untitled172" // add a mapView component MapView { id: mv anchors.fill: parent // set focus to enable keyboard navigation focus: true // add a map to the mapview Map { // add the ArcGISStreets basemap to the map initBasemapStyle: Enums.BasemapStyleArcGISStreets initialViewpoint: ViewpointExtent { extent: Envelope { id: env json: {"spatialReference":{"latestWkid":3857,"wkid":102100},"xmax":-13013797.089479687,"xmin":-13034963.75614633,"ymax":4036739.5261344,"ymin":4020864.5261344174} } } } GraphicsOverlay { id: graphicsOverlayAddNewPoint Graphic { geometry: Point { x: -117 y: 34 spatialReference: SpatialReference {wkid: 4326} } symbol: SimpleMarkerSymbol { color: "red" } } } Component.onCompleted: { movePoint() } function movePoint() { var refPointList = []; var refPoint = ArcGISRuntimeEnvironment.createObject("Point", { x: -117, y: 34, spatialReference: Factory.SpatialReference.createWgs84()}); refPointList.push(refPoint); var linearUnit = ArcGISRuntimeEnvironment.createObject("LinearUnit", {linearUnitId: Enums.LinearUnitIdKilometers}); var angularUnit = ArcGISRuntimeEnvironment.createObject("AngularUnit", {angularUnitId: Enums.AngularUnitIdDegrees}); var movedPoints = GeometryEngine.moveGeodetic(refPointList, 2, linearUnit, 0, angularUnit, Enums.GeodeticCurveTypeGeodesic); var graphic = ArcGISRuntimeEnvironment.createObject("Graphic", { geometry: movedPoints[0], symbol: ArcGISRuntimeEnvironment.createObject("SimpleMarkerSymbol", {color: "purple"}) }); graphicsOverlayAddNewPoint.graphics.append(graphic); } } }

Re: Adding x and y offset to a Point

lsc — Sat, 21 Oct 2023 06:38:01 GMT

Thank you very much!