内容

• 详细描述
• 用法范例

MapItemGroup QML Type

The MapItemGroup type is a container for map items. 更多...

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详细描述

Its purpose is to enable code modularization by allowing the usage of qml files containing map elements related to each other, and the associated bindings.

注意： The release of this API with Qt 5.9 is a Technology Preview.

用法范例

The following snippet shows how to use a MapItemGroup to create a MapCircle , centered at the coordinate (63, -18) with a radius of 100km, filled in red, surrounded by an ondulated green border, both contained in a semitransparent blue circle with a MouseArea that moves the whole group. This group is defined in a separate file named PolygonGroup.qml:

import QtQuick 2.4
import QtPositioning 5.6
import QtLocation 5.9
MapItemGroup {
    id: itemGroup
    property alias position: mainCircle.center
    property var radius: 100 * 1000
    property var borderHeightPct : 0.3
    MapCircle {
        id: mainCircle
        center : QtPositioning.coordinate(40, 0)
        radius: itemGroup.radius * (1.0 + borderHeightPct)
        opacity: 0.05
        visible: true
        color: 'blue'
        MouseArea{
            anchors.fill: parent
            drag.target: parent
            id: maItemGroup
        }
    }
    MapCircle {
        id: groupCircle
        center: itemGroup.position
        radius: itemGroup.radius
        color: 'crimson'
        onCenterChanged: {
            groupPolyline.populateBorder();
        }
    }
    MapPolyline {
        id: groupPolyline
        line.color: 'green'
        line.width: 3
        function populateBorder() {
            groupPolyline.path = [] // clearing the path
            var waveLength = 8.0;
            var waveAmplitude = groupCircle.radius * borderHeightPct;
            for (var i=0; i <= 360; i++) {
                var wavePhase = (i/360.0 * 2.0 * Math.PI )* waveLength
                var waveHeight = (Math.cos(wavePhase) + 1.0) / 2.0
                groupPolyline.addCoordinate(groupCircle.center.atDistanceAndAzimuth(groupCircle.radius + waveAmplitude * waveHeight , i))
            }
        }
        Component.onCompleted: {
            populateBorder()
        }
    }
}
					

PolygonGroup.qml is now a reusable component that can then be used in a Map as:

Map {
    id: map
    PolygonGroup {
        id: polygonGroup
        position: QtPositioning.coordinate(63,-18)
    }
}