QGCMapPolygonVisuals.qml

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import QtQuick
import QtQuick.Controls
import QtLocation
import QtPositioning
import QtQuick.Dialogs
import QtQuick.Layouts
 
import QGroundControl
import QGroundControl.Controls
import QGroundControl.FlightMap
import QGroundControl.PlanView
 
/// QGCMapPolygon map visuals
Item {
    id: _root
 
    property var    mapControl                                  ///< Map control to place item in
    property var    mapPolygon                                  ///< QGCMapPolygon object
    property bool   interactive:        mapPolygon.interactive
    property color  interiorColor:      "transparent"
    property color  altColor:           "transparent"
    property real   interiorOpacity:    1
    property int    borderWidth:        0
    property color  borderColor:        "black"
 
    property bool   _circleMode:                false
    property real   _circleRadius
    property bool   _circleRadiusDrag:          false
    property var    _circleRadiusDragCoord:     QtPositioning.coordinate()
    property string _instructionText:           _polygonToolsText
    property var    _savedVertices:             [ ]
    property bool   _savedCircleMode
    property bool   _isVertexBeingDragged:      false
 
    property real _zorderDragHandle:    QGroundControl.zOrderMapItems + 3   // Highest to prevent splitting when items overlap
    property real _zorderSplitHandle:   QGroundControl.zOrderMapItems + 2
    property real _zorderCenterHandle:  QGroundControl.zOrderMapItems + 1   // Lowest such that drag or split takes precedence
 
    readonly property string _polygonToolsText: qsTr("Polygon Tools")
    readonly property string _traceText:        qsTr("Click in the map to add vertices. Click 'Done Tracing' when finished.")
 
    function addCommonVisuals() {
        if (_objMgrCommonVisuals.empty) {
            _objMgrCommonVisuals.createObject(polygonComponent, mapControl, true)
        }
    }
 
    function removeCommonVisuals() {
        _objMgrCommonVisuals.destroyObjects()
    }
 
    function addEditingVisuals() {
        if (_objMgrEditingVisuals.empty) {
            _objMgrEditingVisuals.createObjects(
                [ dragHandlesComponent, splitHandlesComponent, centerDragHandleComponent, edgeLengthHandlesComponent ],
                mapControl,
                false /* addToMap */)
        }
    }
 
    function removeEditingVisuals() {
        _objMgrEditingVisuals.destroyObjects()
    }
 
    function addToolbarVisuals() {
        if (_objMgrToolVisuals.empty) {
            var toolbar = _objMgrToolVisuals.createObject(toolbarComponent, mapControl)
            toolbar.z = QGroundControl.zOrderWidgets
        }
    }
 
    function removeToolVisuals() {
        _objMgrToolVisuals.destroyObjects()
    }
 
    function addCircleVisuals() {
        if (_objMgrCircleVisuals.empty) {
            _objMgrCircleVisuals.createObject(radiusVisualsComponent, mapControl)
        }
    }
 
    /// Calculate the default/initial 4 sided polygon
    function defaultPolygonVertices() {
        // Initial polygon is inset to take 2/3rds space
        var rect = Qt.rect(mapControl.centerViewport.x, mapControl.centerViewport.y, mapControl.centerViewport.width, mapControl.centerViewport.height)
        rect.x += (rect.width * 0.25) / 2
        rect.y += (rect.height * 0.25) / 2
        rect.width *= 0.75
        rect.height *= 0.75
 
        var centerCoord =       mapControl.toCoordinate(Qt.point(rect.x + (rect.width / 2), rect.y + (rect.height / 2)),   false /* clipToViewPort */)
        var topLeftCoord =      mapControl.toCoordinate(Qt.point(rect.x, rect.y),                                          false /* clipToViewPort */)
        var topRightCoord =     mapControl.toCoordinate(Qt.point(rect.x + rect.width, rect.y),                             false /* clipToViewPort */)
        var bottomLeftCoord =   mapControl.toCoordinate(Qt.point(rect.x, rect.y + rect.height),                            false /* clipToViewPort */)
        var bottomRightCoord =  mapControl.toCoordinate(Qt.point(rect.x + rect.width, rect.y + rect.height),               false /* clipToViewPort */)
 
        // Initial polygon has max width and height of 3000 meters
        var halfWidthMeters =   Math.min(topLeftCoord.distanceTo(topRightCoord), 3000) / 2
        var halfHeightMeters =  Math.min(topLeftCoord.distanceTo(bottomLeftCoord), 3000) / 2
        topLeftCoord =      centerCoord.atDistanceAndAzimuth(halfWidthMeters, -90).atDistanceAndAzimuth(halfHeightMeters, 0)
        topRightCoord =     centerCoord.atDistanceAndAzimuth(halfWidthMeters, 90).atDistanceAndAzimuth(halfHeightMeters, 0)
        bottomLeftCoord =   centerCoord.atDistanceAndAzimuth(halfWidthMeters, -90).atDistanceAndAzimuth(halfHeightMeters, 180)
        bottomRightCoord =  centerCoord.atDistanceAndAzimuth(halfWidthMeters, 90).atDistanceAndAzimuth(halfHeightMeters, 180)
 
        return [ topLeftCoord, topRightCoord, bottomRightCoord, bottomLeftCoord  ]
    }
 
    /// Reset polygon back to initial default
    function _resetPolygon() {
        mapPolygon.beginReset()
        mapPolygon.clear()
        mapPolygon.appendVertices(defaultPolygonVertices())
        mapPolygon.endReset()
        _circleMode = false
    }
 
    function _createCircularPolygon(center, radius) {
        var unboundCenter = center.atDistanceAndAzimuth(0, 0)
        var segments = 16
        var angleIncrement = 360 / segments
        var angle = 0
        mapPolygon.beginReset()
        mapPolygon.clear()
        _circleRadius = radius
        for (var i=0; i<segments; i++) {
            var vertex = unboundCenter.atDistanceAndAzimuth(radius, angle)
            mapPolygon.appendVertex(vertex)
            angle += angleIncrement
        }
        mapPolygon.endReset()
        _circleMode = true
    }
 
    /// Reset polygon to a circle which fits within initial polygon
    function _resetCircle() {
        var initialVertices = defaultPolygonVertices()
        var width = initialVertices[0].distanceTo(initialVertices[1])
        var height = initialVertices[1].distanceTo(initialVertices[2])
        var radius = Math.min(width, height) / 2
        var center = initialVertices[0].atDistanceAndAzimuth(width / 2, 90).atDistanceAndAzimuth(height / 2, 180)
        _createCircularPolygon(center, radius)
    }
 
    function _handleInteractiveChanged() {
        if (interactive) {
            addEditingVisuals()
            addToolbarVisuals()
        } else {
            mapPolygon.traceMode = false
            removeEditingVisuals()
            removeToolVisuals()
        }
    }
 
    function _saveCurrentVertices() {
        _savedVertices = [ ]
        _savedCircleMode = _circleMode
        for (var i=0; i<mapPolygon.count; i++) {
            _savedVertices.push(mapPolygon.vertexCoordinate(i))
        }
    }
 
    function _restorePreviousVertices() {
        mapPolygon.beginReset()
        mapPolygon.clear()
        for (var i=0; i<_savedVertices.length; i++) {
            mapPolygon.appendVertex(_savedVertices[i])
        }
        mapPolygon.endReset()
        _circleMode = _savedCircleMode
    }
 
    onInteractiveChanged: _handleInteractiveChanged()
 
    on_CircleModeChanged: {
        if (_circleMode) {
            addCircleVisuals()
        } else {
            _objMgrCircleVisuals.destroyObjects()
        }
    }
 
    Connections {
        target: mapPolygon
        function onTraceModeChanged(traceMode) {
            if (traceMode) {
                _instructionText = _traceText
                _objMgrTraceVisuals.createObject(traceMouseAreaComponent, mapControl, false)
            } else {
                _instructionText = _polygonToolsText
                _objMgrTraceVisuals.destroyObjects()
            }
        }
    }
 
    Component.onCompleted: {
        addCommonVisuals()
        _handleInteractiveChanged()
    }
    Component.onDestruction: mapPolygon.traceMode = false
 
    QGCDynamicObjectManager { id: _objMgrCommonVisuals }
    QGCDynamicObjectManager { id: _objMgrToolVisuals }
    QGCDynamicObjectManager { id: _objMgrEditingVisuals }
    QGCDynamicObjectManager { id: _objMgrTraceVisuals }
    QGCDynamicObjectManager { id: _objMgrCircleVisuals }
 
    QGCPalette { id: qgcPal }
 
    KMLOrSHPFileDialog {
        id:             kmlOrSHPLoadDialog
        title:          qsTr("Select Polygon File")
 
        onAcceptedForLoad: (file) => {
            mapPolygon.loadKMLOrSHPFile(file)
            mapFitFunctions.fitMapViewportToMissionItems()
            close()
        }
    }
 
    QGCMenu {
        id: menu
 
        property int _editingVertexIndex: -1
 
        function popupVertex(curIndex) {
            menu._editingVertexIndex = curIndex
            removeVertexItem.visible = (mapPolygon.count > 3 && menu._editingVertexIndex >= 0)
            menu.popup()
        }
 
        function popupCenter() {
            menu.popup()
        }
 
        QGCMenuItem {
            id:             removeVertexItem
            visible:        !_circleMode
            text:           qsTr("Remove vertex")
            onTriggered: {
                if (menu._editingVertexIndex >= 0) {
                    mapPolygon.removeVertex(menu._editingVertexIndex)
                }
            }
        }
 
        QGCMenuSeparator {
            visible:        removeVertexItem.visible
        }
 
        QGCMenuItem {
            text:           qsTr("Set radius..." )
            visible:        _circleMode
            onTriggered:    editCircleRadiusDialogFactory.open()
        }
 
        QGCMenuItem {
            text:           qsTr("Edit position..." )
            visible:        _circleMode
            onTriggered:    editCenterPositionDialogFactory.open()
        }
 
        QGCMenuItem {
            text:           qsTr("Edit position..." )
            visible:        !_circleMode && menu._editingVertexIndex >= 0
            onTriggered:    editVertexPositionDialogFactory.open()
        }
    }
 
    Component {
        id: polygonComponent
 
        MapPolygon {
            color:          mapPolygon.showAltColor ? altColor : interiorColor
            opacity:        interiorOpacity
            visible:        _root.visible
            border.color:   mapPolygon.vertexDrag ? "orange" : borderColor
            border.width:   mapPolygon.vertexDrag ? 3 : borderWidth
            path:           mapPolygon.vertexDrag ? mapPolygon.dragPath : mapPolygon.path
        }
    }
 
    Component {
        id: edgeLengthHandleComponent
 
        MapQuickItem {
            id:             mapQuickItem
            anchorPoint.x:  sourceItem.width / 2
            anchorPoint.y:  sourceItem.height / 2
            visible:        !_circleMode
 
            property int vertexIndex
            property real distance
 
            property var _unitsConversion: QGroundControl.unitsConversion
 
            sourceItem: Text {
              text:     _unitsConversion.metersToAppSettingsHorizontalDistanceUnits(distance).toFixed(1) + " " +
                        _unitsConversion.appSettingsHorizontalDistanceUnitsString
              color:    "white"
            }
        }
    }
 
    Component {
        id: edgeLengthHandlesComponent
 
        Repeater {
            model: _isVertexBeingDragged ? mapPolygon.path : undefined
 
            delegate: Item {
                property var _edgeLengthHandle
 
                function _setHandlePosition() {
                    var vertices = mapPolygon.vertexDrag ? mapPolygon.dragPath : mapPolygon.path
                    var nextIndex = index + 1
                    if (nextIndex > vertices.length - 1) {
                        nextIndex = 0
                    }
                    var distance = vertices[index].distanceTo(vertices[nextIndex])
                    var azimuth = vertices[index].azimuthTo(vertices[nextIndex])
                    _edgeLengthHandle.coordinate = vertices[index].atDistanceAndAzimuth(distance / 2, azimuth)
                    _edgeLengthHandle.distance = distance
                }
 
                Connections {
                    target: mapPolygon
                    function onDragPathChanged() { _setHandlePosition() }
                }
 
                Component.onCompleted: {
                    _edgeLengthHandle = edgeLengthHandleComponent.createObject(mapControl)
                    _edgeLengthHandle.vertexIndex = index
                    _setHandlePosition()
                    mapControl.addMapItem(_edgeLengthHandle)
                }
 
                Component.onDestruction: {
                    if (_edgeLengthHandle) {
                        _edgeLengthHandle.destroy()
                    }
                }
            }
        }
    }
 
    Component {
        id: splitHandleComponent
 
        MapQuickItem {
            id:             mapQuickItem
            anchorPoint.x:  sourceItem.width / 2
            anchorPoint.y:  sourceItem.height / 2
            visible:        !_circleMode && !_isVertexBeingDragged && !mapPolygon.centerDrag
 
            property int vertexIndex
 
            sourceItem: SplitIndicator {
                z:          _zorderSplitHandle
                onClicked:  if(_root.interactive) mapPolygon.splitPolygonSegment(mapQuickItem.vertexIndex)
            }
        }
    }
 
    Component {
        id: splitHandlesComponent
 
        Repeater {
            model: mapPolygon.path
 
            delegate: Item {
                property var _splitHandle
                property var _vertices:     mapPolygon.path
 
                function _setHandlePosition() {
                    var nextIndex = index + 1
                    if (nextIndex > _vertices.length - 1) {
                        nextIndex = 0
                    }
                    var distance = _vertices[index].distanceTo(_vertices[nextIndex])
                    var azimuth = _vertices[index].azimuthTo(_vertices[nextIndex])
                    _splitHandle.coordinate = _vertices[index].atDistanceAndAzimuth(distance / 2, azimuth)
                }
 
                Component.onCompleted: {
                    _splitHandle = splitHandleComponent.createObject(mapControl)
                    _splitHandle.vertexIndex = index
                    _setHandlePosition()
                    mapControl.addMapItem(_splitHandle)
                }
 
                Component.onDestruction: {
                    if (_splitHandle) {
                        _splitHandle.destroy()
                    }
                }
            }
        }
    }
 
    // Control which is used to drag polygon vertices
    Component {
        id: dragAreaComponent
 
        MissionItemIndicatorDrag {
            id:             dragArea
            mapControl:     _root.mapControl
            z:              _zorderDragHandle
            visible:        !_circleMode
            onDragStart:    { _isVertexBeingDragged = true; mapPolygon.vertexDrag = true }
            onDragStop:     { _isVertexBeingDragged = false; mapPolygon.vertexDrag = false; mapPolygon.verifyClockwiseWinding() }
 
            property int polygonVertex
 
            property bool _creationComplete: false
 
            Component.onCompleted: _creationComplete = true
 
            onItemCoordinateChanged: {
                if (_creationComplete) {
                    // During component creation some bad coordinate values got through which screws up draw
                    mapPolygon.adjustVertex(polygonVertex, itemCoordinate)
                }
            }
 
            onClicked: if(_root.interactive) menu.popupVertex(polygonVertex)
        }
    }
 
    Component {
        id: centerDragHandle
        MapQuickItem {
            id:             mapQuickItem
            anchorPoint.x:  dragHandle.width  * 0.5
            anchorPoint.y:  dragHandle.height * 0.5
            z:              _zorderDragHandle
            visible:        !_isVertexBeingDragged
            sourceItem: Rectangle {
                id:             dragHandle
                width:          ScreenTools.defaultFontPixelHeight * 1.5
                height:         width
                radius:         width * 0.5
                color:          Qt.rgba(1,1,1,0.8)
                border.color:   Qt.rgba(0,0,0,0.25)
                border.width:   1
                QGCColoredImage {
                    width:      parent.width
                    height:     width
                    color:      Qt.rgba(0,0,0,1)
                    mipmap:     true
                    fillMode:   Image.PreserveAspectFit
                    source:     "/qmlimages/MapCenter.svg"
                    sourceSize.height:  height
                    anchors.centerIn:   parent
                }
            }
        }
    }
 
    Component {
        id: dragHandleComponent
 
        MapQuickItem {
            id:             mapQuickItem
            anchorPoint.x:  dragHandle.width  / 2
            anchorPoint.y:  dragHandle.height / 2
            z:              _zorderDragHandle
            visible:        !_circleMode && !mapPolygon.centerDrag
 
            property int polygonVertex
 
            sourceItem: Rectangle {
                id:             dragHandle
                width:          ScreenTools.defaultFontPixelHeight * 1.5
                height:         width
                radius:         width * 0.5
                color:          Qt.rgba(1,1,1,0.8)
                border.color:   Qt.rgba(0,0,0,0.25)
                border.width:   1
            }
        }
    }
 
    // Add all polygon vertex drag handles to the map
    Component {
        id: dragHandlesComponent
 
        Repeater {
            model: mapPolygon.pathModel
 
            delegate: Item {
                property var _visuals: [ ]
 
                Component.onCompleted: {
                    var dragHandle = dragHandleComponent.createObject(mapControl)
                    dragHandle.coordinate = Qt.binding(function() { return object.coordinate })
                    dragHandle.polygonVertex = Qt.binding(function() { return index })
                    mapControl.addMapItem(dragHandle)
                    var dragArea = dragAreaComponent.createObject(mapControl, { "itemIndicator": dragHandle, "itemCoordinate": object.coordinate })
                    dragArea.polygonVertex = Qt.binding(function() { return index })
                    _visuals.push(dragHandle)
                    _visuals.push(dragArea)
                }
 
                Component.onDestruction: {
                    for (var i=0; i<_visuals.length; i++) {
                        _visuals[i].destroy()
                    }
                    _visuals = [ ]
                }
            }
        }
    }
 
    QGCPopupDialogFactory {
        id: editCircleRadiusDialogFactory
 
        dialogComponent: editCircleRadiusDialog
    }
 
    Component {
        id: editCircleRadiusDialog
 
        QGCPopupDialog {
            id:         popupDialog
            title:      qsTr("Set Radius")
            buttons:    Dialog.Save | Dialog.Cancel
 
            onAccepted: {
                const appRadius = Number(radiusField.text)
                if (!isNaN(appRadius) && appRadius > 0) {
                    const radiusMeters = QGroundControl.unitsConversion.appSettingsHorizontalDistanceUnitsToMeters(appRadius)
                    _createCircularPolygon(mapPolygon.center, radiusMeters)
                } else {
                    preventClose = true
                }
            }
 
            ColumnLayout {
                width:      ScreenTools.defaultFontPixelWidth * 30
                spacing:    ScreenTools.defaultFontPixelHeight
 
                QGCLabel {
                    Layout.fillWidth:   true
                    text:               qsTr("Enter circle radius.")
                    wrapMode:           Text.WordWrap
                }
 
                QGCTextField {
                    id:                 radiusField
                    Layout.fillWidth:   true
                    text:               QGroundControl.unitsConversion.metersToAppSettingsHorizontalDistanceUnits(_circleRadius).toFixed(1)
                    validator:          DoubleValidator { bottom: 0.1; notation: DoubleValidator.StandardNotation }
                    inputMethodHints:   Qt.ImhFormattedNumbersOnly
                }
 
                QGCLabel {
                    Layout.fillWidth:   true
                    text:               QGroundControl.unitsConversion.appSettingsHorizontalDistanceUnitsString
                }
            }
        }
    }
 
    QGCPopupDialogFactory {
        id: editCenterPositionDialogFactory
 
        dialogComponent: editCenterPositionDialog
    }
 
    Component {
        id: editCenterPositionDialog
 
        EditPositionDialog {
            title:      qsTr("Edit Center Position")
            coordinate: mapPolygon.center
            onCoordinateChanged: {
                // Prevent spamming signals on vertex changes by setting centerDrag = true when changing center position.
                // This also fixes a bug where Qt gets confused by all the signalling and draws a bad visual.
                mapPolygon.centerDrag = true
                mapPolygon.center = coordinate
                mapPolygon.centerDrag = false
            }
        }
    }
 
    QGCPopupDialogFactory {
        id: editVertexPositionDialogFactory
 
        dialogComponent: editVertexPositionDialog
    }
 
    Component {
        id: editVertexPositionDialog
 
        EditPositionDialog {
            title:      qsTr("Edit Vertex Position")
            coordinate: mapPolygon.vertexCoordinate(menu._editingVertexIndex)
            onCoordinateChanged: {
                mapPolygon.adjustVertex(menu._editingVertexIndex, coordinate)
                mapPolygon.verifyClockwiseWinding()
            }
        }
    }
 
    Component {
        id: centerDragAreaComponent
 
        MissionItemIndicatorDrag {
            mapControl:                 _root.mapControl
            z:                          _zorderCenterHandle
            onItemCoordinateChanged:    mapPolygon.center = itemCoordinate
            onDragStart:                { mapPolygon.centerDrag = true; mapPolygon.vertexDrag = true }
            onDragStop:                 { mapPolygon.centerDrag = false; mapPolygon.vertexDrag = false }
            onClicked:                  if(_root.interactive) menu.popupCenter()
        }
    }
 
    Component {
        id: centerDragHandleComponent
 
        Item {
            property var dragHandle
            property var dragArea
 
            Component.onCompleted: {
                dragHandle = centerDragHandle.createObject(mapControl)
                dragHandle.coordinate = Qt.binding(function() { return mapPolygon.centerDrag ? mapPolygon.dragCenter : mapPolygon.center })
                mapControl.addMapItem(dragHandle)
                dragArea = centerDragAreaComponent.createObject(mapControl, { "itemIndicator": dragHandle, "itemCoordinate": mapPolygon.center })
            }
 
            Component.onDestruction: {
                dragHandle.destroy()
                dragArea.destroy()
            }
        }
    }
 
    Component {
        id: toolbarComponent
 
        PlanEditToolbar {
            anchors.horizontalCenter:       mapControl.left
            anchors.horizontalCenterOffset: mapControl.centerViewport.left + (mapControl.centerViewport.width / 2)
            y:                              mapControl.centerViewport.top
            availableWidth:                 mapControl.centerViewport.width
 
            QGCButton {
                _horizontalPadding: 0
                text:               qsTr("Basic")
                visible:            !mapPolygon.traceMode
                onClicked:          _resetPolygon()
            }
 
            QGCButton {
                _horizontalPadding: 0
                text:               qsTr("Circular")
                visible:            !mapPolygon.traceMode
                onClicked:          _resetCircle()
            }
 
            QGCButton {
                _horizontalPadding: 0
                text:               mapPolygon.traceMode ? qsTr("Done Tracing") : qsTr("Trace")
                onClicked: {
                    if (mapPolygon.traceMode) {
                        if (mapPolygon.count < 3) {
                            _restorePreviousVertices()
                        }
                        mapPolygon.traceMode = false
                    } else {
                        _saveCurrentVertices()
                        _circleMode = false
                        mapPolygon.traceMode = true
                        mapPolygon.clear();
                    }
                }
            }
 
            QGCButton {
                _horizontalPadding: 0
                text:               qsTr("Load KML/SHP...")
                onClicked:          kmlOrSHPLoadDialog.openForLoad()
                visible:            !mapPolygon.traceMode
            }
        }
    }
 
    // Mouse area to capture clicks for tracing a polygon
    Component {
        id:  traceMouseAreaComponent
 
        MouseArea {
            anchors.fill:       mapControl
            preventStealing:    true
            z:                  QGroundControl.zOrderMapItems + 1   // Over item indicators
 
            onClicked: (mouse) => {
                if (mouse.button === Qt.LeftButton && _root.interactive) {
                    mapPolygon.appendVertex(mapControl.toCoordinate(Qt.point(mouse.x, mouse.y), false /* clipToViewPort */))
                }
            }
        }
    }
 
    Component {
        id: radiusDragHandleComponent
 
        MapQuickItem {
            id:             mapQuickItem
            anchorPoint.x:  dragHandle.width / 2
            anchorPoint.y:  dragHandle.height / 2
            z:              QGroundControl.zOrderMapItems + 2
            visible:        !mapPolygon.centerDrag
 
            sourceItem: Rectangle {
                id:         dragHandle
                width:      ScreenTools.defaultFontPixelHeight * 1.5
                height:     width
                radius:     width / 2
                color:      "white"
                opacity:    interiorOpacity * .90
            }
        }
    }
 
    Timer {
        id: radiusDragDebounceTimer
        interval: 0
        repeat: false
 
        property var pendingCoord: undefined
 
        onTriggered: {
            // re-build the circular polygon only once per event loop
            if (pendingCoord) {
                var coord = pendingCoord
                pendingCoord = undefined
                var radius = mapPolygon.center.distanceTo(coord)
                _createCircularPolygon(mapPolygon.center, radius)
            }
        }
    }
 
    Component {
        id: radiusDragAreaComponent
 
        MissionItemIndicatorDrag {
            mapControl: _root.mapControl
            onDragStart: {
                _circleRadiusDrag = true
                mapPolygon.vertexDrag = true
            }
            onDragStop: {
                _circleRadiusDrag = false
                mapPolygon.vertexDrag = false
            }
 
            onItemCoordinateChanged: {
                // Keep the handle visually attached to the cursor while radius updates are de-bounced.
                _circleRadiusDragCoord = itemCoordinate
 
                var radius = mapPolygon.center.distanceTo(itemCoordinate)
 
                if (Math.abs(radius - _circleRadius) > 0.1) {
                    // De-bounced circular polygon re-drawing
                    radiusDragDebounceTimer.pendingCoord = itemCoordinate
                    radiusDragDebounceTimer.start()
                }
            }
        }
    }
 
    Component {
        id: radiusVisualsComponent
 
        Item {
            property var    circleCenterCoord:  mapPolygon.center
 
            function _calcRadiusDragCoord() {
                _circleRadiusDragCoord = circleCenterCoord.atDistanceAndAzimuth(_circleRadius, 90)
            }
 
            onCircleCenterCoordChanged: {
                if (!_circleRadiusDrag) {
                    _calcRadiusDragCoord()
                }
            }
 
            QGCDynamicObjectManager {
                id: _objMgr
            }
 
            Component.onCompleted: {
                _calcRadiusDragCoord()
                var radiusDragHandle = _objMgr.createObject(radiusDragHandleComponent, mapControl, true)
                radiusDragHandle.coordinate = Qt.binding(function() { return _circleRadiusDragCoord })
                var radiusDragIndicator = radiusDragAreaComponent.createObject(mapControl, { "itemIndicator": radiusDragHandle, "itemCoordinate": _circleRadiusDragCoord })
                _objMgr.addObject(radiusDragIndicator)
            }
        }
    }
}