How to replace MapView with separate Pins?

Question

I'm trying to change MapView in my Xamarin Forms app (with Mapsui and Prism), as I need separate view to store Pins. First MapView (let's call it default) is for displaying all pins from list. Second MapView (history) is for displaying new pins, which are removed when leaving Page.

I have Dictionary for storing my MapViews to have easy way to access any view I want. Every created MapView has the same instance of Map. I want to change from default to history which should hide pins that are added in default view.

I change view with this:

public void ChangeView(string name)
        {
            var prev = MapView;
            loggerService.Info($"Pins: {prev.Pins.Count}");
            MapView = GetView(name); // Current MapView in XAML, returns instance of MapView
            loggerService.Info($"New view pins: {MapView.Pins.Count}");

            Task.Factory.StartNew(() => 
            {
                Task.Delay(2000).Wait();

                loggerService.Info($"View pins: {MapView.Pins.Count}");
            });

            MapView.Refresh();
        }

extra code with log is for debugging purposes - it shows correct values (prev pins = 7, new pins = 0, view pins = 0).

I've added history view without Zoom buttons to make sure it is changing - and it is (so there is no need to post XAML, I think).

How should I change MapView to hide pins when navigating to history and show them when I switch back to default view? Or is there a better way to 'group' Pins and hide/show them basing on name?

Update I think this may be important to mention:

public Pin AddMarker(Position point)
        {
            var pin = new Pin(MapView)
            {
                Label = "PinType.Pin",
                Position = point,
                Type = PinType.Pin,
                Transparency = 0.5f,
                Color = Xamarin.Forms.Color.FromRgb(2, 144, 210),
                Scale = 0.5f,
            };

            MapView.Pins.Add(pin);

            return pin;
        }

This is the way I add Pins to view. This is the same MapView as above (all the code is from MapService).

score 0 · Accepted Answer · answered Apr 01 '19 at 19:13

0

Some options

Perhaps you can bind the IsVisible property of the Pins to a HistoryMode field on your view. I never used this myself.
Use some of the lower level functionality. Like
- Use separate layers for default and history and enable/disable them when needed. You might need to do the conversion of WGS84 (gps coordinates) to SphericalMercator. https://mapsui.com/api/Mapsui.Projection.SphericalMercator.html?q=sphericalmercator
- Use a ThemeStyle. It has a method that can be use to specify any style you need (visible/color/symbol) based and the feature attributes. https://mapsui.com/api/Mapsui.Styles.Thematics.ThemeStyle.html?q=themestyle

For the lower level functionality you may need to the samples to get you on your way: https://mapsui.com/documentation/samples.html

answered Apr 01 '19 at 19:13

pauldendulk

1,378
12
23

Thanks for detailed answer. I think the separate layer is the most suitable for my case. But how am I able to hide pins from layer? As I can see, PointsSample covers "points" as bitmap, not built in Pins feature, am I right? – Szymon Jabłoński Apr 02 '19 at 19:52
I dived in MapView code and found out that `Pins` is nothing than predefined layer with `ObservableCollectionProvider` containing Pins. I think I will figure the rest out. Thanks a lot! – Szymon Jabłoński Apr 03 '19 at 18:48
It is always an option to copy the MapView code to your own project and modify it to your needs. – pauldendulk Apr 05 '19 at 11:27
Finally I've changed switching MapViews to switching Layers. Now it's working as expected. – Szymon Jabłoński Apr 12 '19 at 14:24

How to replace MapView with separate Pins?

1 Answers1