I've spent a few hours this rainy afternoon taking my first look as this Map component.

I often struggle with Gambas documentation because I'm really thick, so I'm looking for advice. I started with a new project and just dragged a MapView onto the main form. The first bit of code is quite easy:-

Then I added some code based upon an example I found from a French guy, which I've called showMethod1:-


This code works, but I have 2 problems with it; I don't think I have ever seen the "!" used this way, and the autocomplete doesn't seem to recognise the "Points" method (…at least I assume its a method).

I then re-wrote the code as showMethod2, which also works:-


Again, this code doesn't look much like anything in the user documentation. I also can't see any manual reference to:-


…which seems to be the undocumented default Method to setup the Lat & Lon Properties. So for displayMethod3 I created a new instance of MapPoint and set these two properties individually.


So your views & comments would be appreciated, even if it turns out I've missed something important in the documentation.


However, zooming the map and drawing polylines & circles is more straightforward:-

(Click to enlarge)

SteveDee,
The exclamation point (! or 'bang') looks like a dictionary access operator that I used to see in VB/VBA.

https://social.msdn.microsoft.com/Forums/en-US/1393df69-929e-49c6-93b0-5cb0fa7a6430/what-is-a-operator
vb.net - What does this { ! } mean in the specific line of code? - Stack Overflow

I was never fond of it myself, and went out of my way to use the other syntax.
Steve S
PS – thanks for sharing, will be watching where you get with the map component…
_________________

stevedee said

Code (gambas)

1. Public Sub showMethod1()
2.  
3.   MapView1.Map.AddShape("downtown")
4.   MapView1.Map!downtown.AddPoint("church", MapPoint(51.059, -0.33))
5.   MapView1.Map.Center = MapView1.Map!downtown!church.Points
6.  
7. End

This code works, but I have 2 problems with it; I don't think I have ever seen the "!" used this way, and the autocomplete doesn't seem to recognise the "Points" method (…at least I assume its a method).

I then re-wrote the code as showMethod2, which also works:-

Code (gambas)

1. Public Sub showMethod2()
2.  
3.   MapView1.Map.AddShape("downtown")
4.   MapView1.Map["downtown"].AddPoint("church", MapPoint(51.059, -0.33))
5.   MapView1.Map.Center = MapView1.Map["downtown"]["church"].Points
6.  
7. End

sjsepan said

…The exclamation point (! or 'bang') looks like a dictionary access operator…

Thanks Steve, that's another clue.

I'm familiar with "!" being using to access fields in a database, like this extract from one of my old Gambas projects:-


… but I don't think I've ever seen it used in Gambas beyond that. Maybe "!" can be used to access the elements in a collection or an array? I cant see anything about this in the documentation, so I'll have to experiment.

sjsepan said

The exclamation point (! or 'bang') looks like a dictionary access operator…

You are spot-on Steve.

Generally, there are 3 collection types in computer science; array, set & dictionary

In Gambas (& VB) a Collection is basically a Dictionary, and we can use the "!" as follows:-


…or use this method:-

Ok, I now have a much better idea of how to use the Map component. Here is a simplified example, which uses the MapView graphical component as a drawing area.

The first step is to select a map. I'm using a free "Hike & Bike" OpenStreetMap, and the terms & conditions require me to display a copyright message:-

   MapView1.Map.AddTile("openstreet", "https://tiles.wmflabs.org/hikebike/\{z}/{x}/{y}.png").Copyright = "© OpenStreetMap Contributors"

This one line of code is all you need to display a world map which can be zoomed using the display controls.

To plot data (such as a route recorded on a gps device) the data needs to be prepared as a series of MapPoints, where each point consists of a Latitude and a Longitude which must be added to a Gambas collection:-

Or:-   

We need to add a MapShape layer & give it a simple string name (a key):-


It would be nice to have a balloon shaped flag at the start of route. This also needs a key/name, so lets call it "starter":-


When the map is displayed, I'd like it centred on my starting point:-


…which simply centres the map at "starter" on the "outdoor" MapShape layer.

Now we can plot the route data in myRoute as a series of linked red lines, giving it a key/name ("walkies"):-


One final touch is to zoom in to get a more "local" view:-




I will post an example project under Project Showcase for anyone interested.

Hello
…from Wiki of italian Gambas Forum:

Guide della comunità - Gambas-it.org - Wikipedia

vuott said

…from Wiki of italian Gambas Forum…

Many thanks vuott, that looks like a great resource.

This image shows an English translation of topics:-

(Click to enlarge)