UPD: Done. Look at this beautiful polygon.
UPD: In Flutter / openstreetmap, I want to let users draw a polygon by tapping a map and/or clicking a button. The polygon should be not filled. I need a very simple example just to get an idea of how it works.
The final task is:
I am making a flutter application that should give the user the ability to get information about markers located within a certain area on the map. I use osm. By pressing the button, the user initiates the construction of an arbitrary polygon, each corner of which is formed at the place of the next pressing of the button. When the construction of the polygon is completed, the objects inside the polygon are shown, the rest are hidden or not built. After that, the cycle ends by clearing the map.
I haven't found any solution for osm. I would appreciate any help. I don't have any code yet)
You can use the flutter_map library, I'm sure you can understand the documentation and how to set it up.
Then use PolygonLayerOptions(polygons: [Polygon(points: polygonList)]) as a layer on top of the OSM layer. Then set up the list polygonList and use the FlutterMap()'s onTap callback to get the position at which the user tapped and add the LatLng to the polygonList list. There are multiple other configuration options within the Polygon() constructor, and those can be found through IntelliSense or similar. To have no fill, just set the color to transparent.
I use this method (or a very similar one) for my app which lets users download areas of map. The user taps the top left and bottom right of a rectangular area they want to download, by code calculates the top right and bottom left, and a polygon is drawn to show the user exactly where they tapped. Make sure to use setState() or similar.
Related
Fairly new to Mapbox and getting there (slowly).
I have a map initially loaded at zoom level 1 for use in a web browser. When a user clicks on a marker, it'll center and zoom to level 10.
When that marker loses focus, I'd like to zoom back out to level 1.
This page discussing web applications does it (link below), but there doesn't seem to be (that I can find - sorry!) any documentation on how to achieve this.
https://docs.mapbox.com/help/getting-started/web-apps/
Any and all help appreciated!
For the first event, to zoom in when clicking a marker, you could adapt this example to zoom in addition to panning when calling flyTo
https://docs.mapbox.com/mapbox-gl-js/example/center-on-feature/
For the second part, you'd need to add a listener for another event depending on what you have in mind by "losing focus".
https://docs.mapbox.com/mapbox-gl-js/api/map/#map-events
I have this basic application where with a help of a REST API backend I fetch some custom locations(with lat long values).
I call this GET api, with a given boundary of NE and SW latlong values. So after the network call executes it gives me a list of custom markers where then I draw the google map on the screen and draw(overlay) these markers on top of the map.
The full set of markers will be fetched as explained above in init() method when Home Screen loads. so when user sees the map the custom markers are already there and visible.
This approach takes time when there are few hundred of markers coming from that GET api call.
Instead I want to modify the app so. when user sees the map view, it should inly load markers in that visible screen area(of the map) only. and when user moves from that area to another then the markers which should be in that new area comes to visible. and so on and so forth.
I am not sure of how to execute such a thing with flutter.
Can I get some guidance help on this?
I am using leafletjs in a project. On the map I have several polygons and markers. There is a click event on all of them to display some information when one of them is clicked. I would like to take the information away if the user clicks on a 'blank' part of the map (not on any polygons or markers). I know the map has the 'click' event but so far I am struggling to find a way to detect if the user clicked on a layer. Any advice?
you can use preclick event to clear all the data
https://leafletjs.com/reference-1.2.0.html#map-preclick
I have had a look around online to try and find out the best way to draw a line showing the route a user has travelled. I think I need to use the MKOverlayView, and I guess I need to collect a selection of data points to plot (would these be GPS coordinates?). The question I have is based on how I would draw the line and keep adding to it as the users location updates?
I also want to be able to clear the line when a user presses a button. How would I implement this (not the button press, just the code to clear the line off the map view)?
Thanks in advance!
You can do this using MKPolyline. At First you need to get coordinates of route, then draw polylines over it. You will find an example here to draw polyline over some coordinates.
I am interested in adding an option to my GIS Map application, the ability to draw Polygon, circle, polyroutes overlays for the user to search data within.The problem is that I've read and tested codes of how to draw an overlay, but they are always static.I want it to be dynamic, with dynamic center and points (or radius) set by the user on click.A mystery for me.(I'm a beginner in iPhone programming, this is my first app.)And I'm not using and don't want to use things like ArcGIS API for iPhone.I would appreciate any help.
To let the user "draw" an arbitrary polygon on the map, one approach is to use draggable annotations that represent the corners of the polygon. Provide an "Add Corner" button and some kind of Remove Corner button on each annotation.
See my answer to User creating a box on MKMapView for some more details. On that question though, the OP actually ended up using another solution described in the comments which would work well if the polygons are always rectangles.
For implementing a button in an annotation view (if you want a "Remove Corner" button on the annotations), see my answer to How to get click event from a button added over MKAnnotationView.
Once you a have a polygon or other overlay on the map, dragging it by direct touches may only be possible by adding a gesture recognizer to the map (with its own scrolling turned off) and using a custom MKOverlay and MKOverlayView that allow coordinate changes. Adding a gesture recognizer directly to an MKOverlayView doesn't seem to work and the built-in overlay classes don't allow changes to coordinates.
An alternative to moving by direct touches is putting some controls on the side (Up/Down/Left/Right/etc buttons) that modify the custom overlay.
The Apple sample app Breadcrumb gives an example of a custom overlay/view for a path. In WWDC 2010, the sample app LocationReminders gives an example of a custom overlay/view for a circle that can move and resize.
Finally, when you do a search for businesses, you could use the overlay's boundingMapRect (which is always a rectangle regardless of the overlay's shape) as the bounding box for the initial search and then check if the coordinate of each business found is in the overlay's actual shape using the answer to How to determine if an annotation is inside of MKPolygonView (iOS).