[Interest] How to dynamically add a MapItemView to a Map?

[Kishore J]

Done. https://bugreports.qt.io/browse/QTBUG-55782

Given the limitation, I think my immediate alternative is to create a
MapItemView like component that is instantiated outside and write code in
the map that calls addMapItem and removeMapItem on the map as and when the
list is modified. To the drawing board...

Is the patch for the bug requiring to call addMapItem for each item in the
MapItemView delegate is due for the next release? i.e. 5.8?

How about the bug relating to the setting the center of the map? Its easy
to work around but I want to know if it's me doing something wrong.
--
Regards,
Kishore

On Tue, Sep 6, 2016 at 9:25 PM, Paolo Angelelli <paolo.angelelli at qt.io>
wrote:

> On Tue, 6 Sep 2016 19:04:34 +0530
> Kishore J <kitts.mailinglists at gmail.com> wrote:
>
> > Hi
> >
> > I am inching forward with using QML maps in my C++ application. Now
> > i'm interested in dynamically adding multiple MapItemView objects to
> > a given map.
> >
> >
> > import QtQuick 2.5
> > import QtLocation 5.6
> >
> > Map {
> >     id: map
> >     objectName: "MyMap"
> > //     zoomLevel: (maximumZoomLevel - minimumZoomLevel)/2
> >     zoomLevel: minimumZoomLevel
> >
> >     plugin: Plugin {
> >         name: "here"
> >         PluginParameter {name: "here.app_id"; value: "xxxxx"}
> >         PluginParameter {name: "here.token"; value: "xxxxx"}
> >     }
> > //     activeMapType: supportedMapTypes[3]
> >     center {
> >         latitude: 10
> >         longitude: 20
> >     }
> >
> >     MapCircle {
> >         id: staticCircle
> >         center {
> >             latitude: 5
> >             longitude: 10
> >         }
> >         radius: 500000.0
> >         color: 'yellow'
> >         border.width: 4
> >         border.color: 'yellow'
> >         Component.onCompleted: {
> >             console.debug("Loaded static MapCircle")
> >             console.debug(center + ' radius: ' + radius)
> >         }
> >         Component.onDestruction: {
> >             console.debug("Unloaded static MapCircle")
> >         }
> >     }
> >
> >     MapItemView {
> >         id: mapitemview
> >         objectName: "MyMapItemView"
> >         model: ListModel {
> >             id: list
> >             ListElement{lat: 10; lon: 20; rad: 800000}
> >             ListElement{lat: 30; lon: 40; rad: 700000}
> >         }
> >         delegate: Component {
> >             id: delegate
> >
> >             MapCircle {
> >                 id: dynmapcircle
> >                 center {
> >                     latitude: lat;
> >                     longitude: lon;
> >                 }
> >                 radius: 500000.0
> >                 color: 'black'
> >                 border.width: 4
> >                 border.color: 'black'
> >                 Component.onCompleted: {
> >                     console.count("Loaded a MapCircle")
> >                     map.addMapItem(dynmapcircle)
> >                 }
> >             }
> >         }
> >
> >         Component.onCompleted: {
> >             console.debug("Loaded first MapItemView")
> >             console.debug(model.count)
> >         }
> >         Component.onDestruction: {
> >             console.debug("Unloaded first MapItemView")
> >         }
> >     }
> >
> >     MapItemView {
> >         id: mapitemview2
> >         objectName: "MyMapItemView2"
> >         model: ListModel {
> >             id: list2
> >             ListElement{lat: -10; lon: 20; rad: 800000}
> >             ListElement{lat: -30; lon: 40; rad: 700000}
> >         }
> >         delegate: Component {
> >             id: delegate2
> >
> >             MapCircle {
> >                 id: dynmapcircle2
> >                 center {
> >                     latitude: lat;
> >                     longitude: lon;
> >                 }
> >                 radius: 500000.0
> >                 color: 'blue'
> >                 border.width: 4
> >                 border.color: 'blue'
> >                 Component.onCompleted: {
> >                     console.count("Loaded a MapCircle2")
> >                     map.addMapItem(dynmapcircle2)
> >                 }
> >             }
> >         }
> >
> >         Component.onCompleted: {
> >             console.debug("Loaded second MapItemView")
> >         }
> >         Component.onDestruction: {
> >             console.debug("Unloaded second MapItemView")
> >         }
> >     }
> >
> >     Component.onCompleted:{
> >         center.latitude = 10
> >         center.longitude = 20
> >         console.debug('Loaded map ' + map.center)
> >     }
> >     Component.onDestruction:{
> >         console.debug('Unloaded map')
> >     }
> > }
> >
> > Further, i do not understand why i have to call the map.addMapItem()
> > function for each MapItem. I suspect that, that is the source of my
> > problem. I am currently able to define a separate qml file containing
> > the second MapItemView which i instantiate in C++ and set the map as
> > it's parent but that does not work.
> >
> > Any help would be appreciated.
> > --
> > Regards,
> > Kishore
> >
> > PS: I also seem to be facing another issue where the center value
> > specified in the map initialization does not work and I have to set
> > the center in the onCompleted() slot. Funnily, it only considers the
> > Latitude or Longitude value in the initialization depending on which
> > is first specified!
>
> Hi, for the first question, the answer is "you can't".
> This is a limitation of the current API, and something that might be
> worthwile extending.
> So feel free to send a feature request to jira.
>
> For the second question, please have a look if the (now merged) patch
> fixes your bug
>
> best,
> Paolo
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