c++qtqmlqt5qtlocation

Clearing route and getting way points in QT,QML,C++


I have two questions which are somehow related.

  1. I have created a route on an open street map and I want to extract a list of points that correspond to the way points of the generated route (not just the start and the finish). How can this be achieved? For example I want to extract way points for the generated red route from the image bellow (of course I do not want to extract all the points from a route but from 10 in 10 meters).

enter image description here

  1. How do I erase the generated route with red, and have the original map (without the red route) I have tried many function on the map item but non of them worked. For example I have tried the code below but the red route remains.

    function clearMapDataForSession()
     {
        mapview.clearData();
        routeModel.update()
     }
    

Solution

  • You can get a list of coordinates from the Route by using the properties path or segments. The path property directly gives you a list of coordinates on the given Route, the segments property on the other hand gives you a list of RouteSegments which in turn contain a list of coordinates given by its path property.

    Print the list of Route coordinates via segments:

    var segments = routeModel.get(0).segments
    for (var i = 0; i < segments.length; i++) {
        var path = segments[i].path
        for (var j = 0; j < path.length; j++)
            console.log(path[j])
    }
    

    Print the list of Route coordinates via path:

    var path = routeModel.get(0).path
    for (var i = 0; i < path.length; i++) {
        console.log(path[i])
    }
    

    If you compare the list of coordinates given by the two options, they are the same. The benefit of RouteSegments is that you get the distance of the segment as a property. So if you want to generate a list of coordinates/points on the Route at the same distance, this would help you in writing some sort of an algorithm.

    In order to erase a generated Route you need to call reset() on the RouteModel. If you want to also clear the waypoints of a RouteQuery you should call clearWaypoints() as well.

    import QtQuick 2.15
    import QtQuick.Controls 2.15
    import QtQuick.Layouts 1.15
    import QtLocation 5.15
    import QtPositioning 5.15
    
    ApplicationWindow {
        id: window
        width: 800
        height: 600
        visible: true
        title: qsTr("Map")
    
        header: ToolBar {
            RowLayout {
                anchors.fill: parent
                ToolButton {
                    text: qsTr("Reset")
                    onClicked: {
                        routeQuery.clearWaypoints()
                        routeModel.reset()
                    }
                }
            }
        }
    
        Plugin {
            id: mapPlugin
            name: "osm"
        }
    
        RouteQuery {
            id: routeQuery
        }
    
        RouteModel {
            id: routeModel
            plugin: mapPlugin
            query: routeQuery
            autoUpdate: false
        }
    
        Map {
            id: map
            anchors.fill: parent
            plugin: mapPlugin
            center: QtPositioning.coordinate(59.91, 10.75) // Oslo
            zoomLevel: 14
    
            MapItemView {
                model: routeModel
                delegate: MapRoute {
                    route: routeData
                    line.color: "blue"
                    line.width: 5
                    smooth: true
                    opacity: 0.8
                }
            }
    
            MapItemView {
                model: routeModel.status == RouteModel.Ready ? routeModel.get(0).path : null
                delegate: MapQuickItem {
                    anchorPoint.x: pathMarker.width / 2
                    anchorPoint.y: pathMarker.height / 2
                    coordinate: modelData
    
                    sourceItem: Rectangle {
                        id: pathMarker
                        width: 8
                        height: 8
                        radius: 8
                        border.width: 1
                        border.color: "black"
                        color: "yellow"
                    }
                }
            }
    
            MapItemView {
                model: routeQuery.waypoints
                delegate: MapQuickItem {
                    anchorPoint.x: waypointMarker.width / 2
                    anchorPoint.y: waypointMarker.height / 2
                    coordinate: modelData
    
                    sourceItem: Rectangle {
                        id: waypointMarker
                        width: 10
                        height: 10
                        radius: 10
                        border.width: 1
                        border.color: "black"
                        color: "red"
                    }
                }
            }
    
            MouseArea {
                anchors.fill: parent
                onClicked: {
                    routeQuery.addWaypoint(map.toCoordinate(Qt.point(mouse.x,mouse.y)))
                    routeModel.update()
                }
            }
        }
    }
    

    enter image description here