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).
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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.
I wish to emulate this effect in Xcode with Swift. After some research I managed to find some articles about drawing smooth curves using a set of points .But I am still unclear about how I could to dynamically modify curves when the user touches/holds the screen.
Question :
I know how to make a smooth Bezier curve, but how can I add gesture recognizers such that by dragging the curve its shape changes.
I only need someone to point me in the right direction. Is there a guide or article in particular that could be useful?
Create transparent ControlPointView for every control point of the curve with a size of 50*50pt, so that users can easily tap them and drag.
Add a small image in the middle of every ControlPointView, so that users can see where the control point is located.
Add UIPanGestureRecognizer on every ControlPointView and handle it in view controller.
Use centers of control points to rebuild UIBezierPath every time gesture recognizer's state is changed.
I have an app that I want the user to be able to dray a box around a location, say a parking lot. I can't figure out a good way to let them draw this. I can track a long press, and draw the MKPolygon from the touch points, but I would like them to be able to trace the parking lot, and then get the coordinate values for the corners.
I have no idea how to do this, and any help would be appreciated.
A slightly different and probably easier approach you can try is to let the user specify the corners using draggable annotations.
To start "drawing", place two (or more) annotations to represent the corners of the box. Be sure to use an annotation class that implements setCoordinate: so it's draggable.
The user can drag the corners where they want and tap some button when done at which point you can create the MKPolygon using the annotation coordinates and then remove the annotations.
Or, you can re-create the MKPolygon every time the user finishes dragging an annotation (corner) and the user taps some button to say "done" and then you can remove the annotations.
I am working on an app in which I want similar kind of functionality as that of WebMD body image.
How can I identify which part of image is touched in an optimal way? Do I have to slice the image according to requirements?
How can I add some tags into the image? Similar to the facebook photo upload functionality in iphone.
You need some way to figure out what the user touched, or tried to touch.
You might use a list of annotation-like objects, where each object has a location. When the user touches the image, you'll need to find the annotation in the list that's closest to the touch location and react appropriately. The "optimal" way to do that is probably to use a quad tree. For an iPhone app, though, the number of touchable points is probably pretty small (several dozen?), and a brute force search through the list will probably be more than fast enough.
Another option would be to overlay a transparent view on top of your image for each region that you want the user to be able to touch. Doing this would also make it simple to draw a "tag" at each of those locations.
I want to draw a tile-based overlay on top of a MKMapView, but there's no obvious way to do this.
This appears to be tricky since you can zoom to any level with MKMapView (unlike Google Maps).
Has anyone attempted to do this?
Incase this question is still getting views readers should check out the HazardMap and TileMap demo code from WWDC2010.
I'm working on a game where I need to overlay objects on the map and have them scroll and zoom with the map.
Using annotation views I've been able to solve the first problem and partially solve the second problem. Annotations automatically move with the map. For scaling them, I use the mapView:regionDidChangeAnimated: delegate method to resize my annotations after a zoom event. The problem is that the annotations don't rescale until after the zoom gesture is complete.
I can think of two approaches other than filing a bug with Apple requesting that they provide an API for map overlays:
Put a (mostly invisible) view over the top of the MKMapView that intercepts zoom and scroll events, handles them, and passes them on to the map view.
Customize the open-source RouteMe library with tiles from Open Street Map or CloudMade (the former is slow, the latter costs money). But it's fully open source so you should be able to do overlays to your heart's content. You could also run your own tile server that does the tile overlays on the server.
Something I discovered later:
http://www.gisnotes.com/wordpress/2009/10/iphone-devnote-14-drawing-a-point-line-polygon-on-top-of-mkmapview/
Not quite a tile-based solution, but interesting nonetheless.