QML Maps with Pinch Zoom

From Qt Wiki
Revision as of 13:05, 28 November 2016 by EdwardWelbourne (talk | contribs) (Sub-categorize)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

En Ar Bg De El Es Fa Fi Fr Hi Hu It Ja Kn Ko Ms Nl Pl Pt Ru Sq Th Tr Uk Zh

QML Map using PinchArea to zoom and MouseArea to pan

Qt Mobility's Location plugin provides a very nice QML Map item, but currently leaves navigation up to the developer to implement. Two common navigation methods are using a swipe gesture to pan the map around and using a pinch gesture to zoom in and out.

Having not found any solid examples of how to do these two things together, I thought I would post an example of some code which implement these two features. The code uses the PinchArea element which was introduced in Qt Quick 1.1.

I hope you find this helpful!

import QtQuick 1.1 import QtMobility.location 1.2

Rectangle {

id: pinchmap

property double defaultLatitude: 37.69

property double defaultLongitude: –97.33
property int defaultZoomLevel: 7

property alias mapType: map.mapType

width: 640

height: 350

Map {

id: map

anchors.fill: parent

zoomLevel: pinchmap.defaultZoomLevel
plugin: Plugin { name: "nokia" }
mapType: Map.StreetMap

center: Coordinate {

latitude: pinchmap.defaultLatitude
longitude: pinchmap.defaultLongitude
}
}

PinchArea {

id: pincharea

property double _oldZoom

anchors.fill: parent
function calcZoomDelta(zoom, percent) {
return zoom + Math.log(percent)/Math.log(2)
}
onPinchStarted: {

oldZoom = map.zoomLevel

}
onPinchUpdated: {
map.zoomLevel = calcZoomDelta(oldZoom, pinch.scale)
}
onPinchFinished: {
map.zoomLevel = calcZoomDelta(oldZoom, pinch.scale)
}
}
MouseArea {
id: mousearea
property boolisPanning: false
property intlastX: –1
property intlastY: –1
anchors.fill : parent
onPressed: {

isPanning = true lastX = mouse.x lastY = mouse.y

}
onReleased: {

isPanning = false

}
onPositionChanged: {
if (isPanning) {
var dx = mouse.x -lastX
var dy = mouse.y -lastY
map.pan(-dx, -dy)

lastX = mouse.x lastY = mouse.y

}
}
onCanceled: {

_isPanning = false;

}
}

}