QtLocation map updates

[Lubomir I. Ivanov]

On 27 July 2017 at 19:26, Lubomir I. Ivanov <neolit123 at gmail.com> wrote:
>
> so, everything is pretty much in place including editing

pull request made:
https://github.com/Subsurface-divelog/subsurface/pull/516

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This is a side-by-side implementation of the Qt Location based map
next to our already existing Marble map. Both map implementations now
now exist in the codebase and can be swapped.

It's a bit of patch bomb with ~120 commits and while it goes back and
forth here and there, the patches try to remain small and follow my
thinking process...still, if some refactoring is needed, let me know.

How it works:

The best thing about this map widget is that it can be used for both
the mobile and desktop versions. The mobile version support is not
implemented, as it needs some decision making. The desktop version
support begins with the class dekstop-widgets/mapwidget.cpp which is a
QQuickWidget that loads
a QML file mobile-widgets/qml/MapWidget.qml. All the NO_MARBLE
abstraction is taken care of and MapWidget methods are used instead of
Globe methods. The code in mapwidget.cpp code is minimal as this class
desktop-version specific. The magic happens in the class
mobile-widgets/qmlmapwidgetheloper.cppwhich is the backend of the map
widget. It is instantiated in MapWidget.qml and both the mobile and
desktop version need to communicated with it. A new model is added -
qt-models/maplocationmodel.cppthat deals with the population of
markers on the map.

The map itself supports a context menu
(mobile-widgets/qml/MapWidgetContextMenu.qml) with easy support for
any number of options. Markers on this map can be edited by dragging
instead of a double-click. The right mouse button is not used, while
double-click is used to zoom in over a location or a marker. This is
easy to translate to the mobile version without abstraction, plus on
mobile the Map QML object should already support functionality like
pinch zoom.

For the mobile version the infrastructure should be already in place.
the MapWidget needs to instantiated somewhere, some extra signal/slot
handling needs to be added and it should be good to go (hopefully).

How to build:

- you need Qt 5.9 (i haven't tested with newer or on anything but Win32)
- build using cmake -DNO_MARBLE=1

Next steps would be:

- receive code reviews
- receive feedback on the functionality
- remove Marble from the codebase
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also, it might be a good idea to test deployment before removing Marble.

lubomir
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