I should show a set of markers on map to indicate nearby points of interest. These markers will open public chat rooms by click and therefore I think the users should see short address information about each marker before entering that room without the need to click on the marker. However, if I change marker icons in that sense, some of the markers may collide as you can see below:
What I want to do is showing as many as possible markers without collision and replace the icon of these colliding ones with a very small marker like a dot (and no address information):
I achieved to get this result by performing x-axis sweep algorithm to detect collisions but unfortunately, if a marker stops colliding after the user scrolls the map or it exists from the screen or another markers enters the screens and begins to collide with other markers or the user scrolls to a completely new area,.. this algorithm should be performed again and again at every turn. To eliminate the majority of colliding markers I make use of maps-utils marker clustering but I need a more painstaking methodology to overcome this issue. I consider to implement quadtree but I could not be sure whether it is the best way or not. Any advice?
Example:
IMHO, the best way could be combining zoom level, quad-tree and collision detection. So, in this scenario
Here, quad-tree will be used to reduce size of items(markers) to be performed collision detection algorithm. Because you should interest with only near markers, not whole markers individually.
If you detect colliding items by zoom level (not for only visible region/bounds as you did), you will not face the problems related below
if a marker stops colliding after the user scrolls the map or it exists from the screen or another markers enters the screens and begins to collide with other markers or the user scrolls to a completely new area
Google Maps Android Marker Clustering Utility from
https://developers.google.com/maps/documentation/android-api/utility/marker-clustering does this.
You can try to remove:
mGoogleMap.setMyLocationEnabled(true);
Related
I am building an application which uses Google Maps. When displaying the map, I'm also adding markers. Is there a way to see if there are 2 markers that touch each other, meaning if a part of a marker is on top of another marker? My goal is to be able to find that out and then make them a single bigger marker instead of 2 different markers.
The answer should depend somehow on the marker's icon size and the current map zoom since if I zoom out, there's a bigger chance they might overlap.
There seem to be a library made by Google which clusters a set of markers together automatically when they are close to one another.
The library is the marker clustering utility and instruction can be found here:
https://developers.google.com/maps/documentation/android-api/utility/marker-clustering
I'm developing an application that has the following goal:
Using the google maps android API 2 I get my current position, and as I start walking the application starts drawing the route I take
The twist is that the map is a "blind" map. Meaning the map is hidden, only the Marker of my current position and a dotted line of my route is shown.
Keep in mind I'm a novice developing to Android, so please be specific. (Thank you)
I managed to create the map, get my current position and zoom in to it (Had no sens to see the whole planet while i want only my current position). And it's pretty accurate so far.
The thing is I don't know what should I do from this point on.
Basicly I need a white View between the Marker and the real map. Also as I advance that View should always be on, over the MapFragment/MapView. Also I wish to keep the zoom and drag functionality's of the MapFragment.
How can I achieve this?
At this point I'm opened to any solutions.
(Been browsing for a few days now the developers site, I have seen that with the ViewOverlay class I can put messages over the map, but I'm not sure what would the correct aproach be in my case...)
To hide the whole map behind the white view I would use Polygon class Polygon Even if you specify Polygon to cover the whole map Markers will be still displayed in front of it and as so user's current position marker will be visible. You also will be able to zoom and drag.
To draw line on map use Polyline class Polyline It will draw users path as a polyline. If you want to stick with dotted line you can use Circle objects to create it. Circle
I'm implementing a feature in my app that allows user to manually locate themselves on a map. So I use a pin to represent their location and let user drag it to the place they currently are. The simple solution is to use setDraggable(true) on the marker, but this requires users to hold the marker for 3 or 5 seconds until it is draggable. I think this is quite confusing for many user to use the feature. So, what I want is to make the dragging more responsive by letting users drag them immediately without having to hold it for a while - like how Foursquare does!
What should I do to implement my own dragging feature? If you have any suggestions, please help me and thanks.
Check out the Hailo application. They have a neat workaround for this. It only works when you have one marker to drag.
The trick is to pan the map, instead of moving the marker. They just keep the marker in a view on top of the MapFragment (it's not actually a Marker on the map).
You can then use the map's cameraPosition.target as the location of your marker.
I'm trying to write an Android app that will allow a user to search for a generic destination (e.g., "gas station") and be presented with up to ~5 nearby locations to choose from. The screen results would display the user location in the center, and possible destination options would be indicated by markers.
The trick is that I don't want to rescale the map from its starting scale, and so some of the possible destinations may not be visible on the screen. I want to dynamically draw a clickable direction indicator (such as an arrow) that emanates from the user location and points to any off-screen destination. If there are multiple off-screen destinations, I'd probably want to scale the arrow lengths to indicate relative distances. If the user clicks on the arrow, they should be "teleported" to the off-screen location.
Any thoughts on how to best implement this? The only information I've found on overlays uses static files (Most overlays seem to be just .PNG files for markers; one example had a route that was drawn from an XML file). I'd need to calculate the arrow based on direction
to the destination (direction the arrow points) and the relative distance to that location (arrow length), so the overlay is something I'd have to come up with at run time.
I think the main challenge is drawing the clickable arrows, but another question that comes to mind is, should I search using the Google Maps API, or is this job more suited to the Google Places API?
Thanks!
I guess we should put the teleportation on hold until the problem of a dynamically-drawn, clickable overlay is solved then!
A dynamically-drawn, clickable overlay is merely a subclass of Overlay. You will override one or both of the draw() methods to render your arrows using the Canvas 2D drawing API. You will override onTap() to be notified of taps on the map, to see if they tapped on an arrow. You add the overlay to the MapView via addOverlays().add().
Most overlays seem to be just .PNG files for markers
Those are usually ItemizedOverlay classes. That's much simpler to implement, particularly if you are one of those developers (like me) who is all thumbs when it comes to Canvas. However, you cannot achieve what you want with an ItemizedOverlay, in all likelihood.
I'd need to calculate the arrow based on direction to the destination (direction the arrow points) and the relative distance to that location (arrow length), so the overlay is something I'd have to come up with at run time.
Correct. You can use a Projection to help convert between pixel space and geo-space (latitude and longitude), if needed.
Note that this all assumes you are trying to use MapActivity and MapView. You are also welcome to use WebView or a plain browser to bring up your own JavaScript-based maps, if you prefer.
I have faced some problems with the Android MapView API. I get OverlayItems from a database which I want to display in a MapView. If I'm displaying 100 Icons, I have no issues, but if it gets more - like 500 Items in one City - it first looks really bad, while second it slows down a lot. Unfortunately my goal is to display 10000 of them. I think one solution can be to register a listener to ZoomLevels to make them appear/dissapear, but I couldn't find that functionality. Second, I couldn't find a function to scale my Overlays with the Zoom of the Map.
Any Ideas are very welcome
There is a very strange behavior in ItemizedOverlay draw method. When you say: Draw line from (x,y) to (x1,y1) the draw method is called about 20-30-40 times - i don't know why. It is acceptable when you draw one line, but when you draw a thousands of lines,icons and so on...it is very very bad! To solve this problem you should create a cached overlay. This is overlay that catches the first draw, creates the object and then prevents the future draws that do the same draw.
A cluster is a dozen of icons behind one icon. For example if you have 1000 markers on the map, in a specific minimal zoom level you can not see each marker separately - it becomes a mess of icons and colors and so on. And instead of 100 markers that are very very close one by one you place a cluster marker. And on zoom in remove this cluster and create another clusters...do this until the markers became far enough away and you can seen them divided.
Check this: Cluster markers
Take the following approaches:
Create a cached overlay to prevent multiple drawing of same clusters;
Draw in thread;
Cluster your markers depending on zoom level and marker proximity.
Each time you draw in the overlay, check for sure is the current marker inside of the visible part of the screen. If it is not, do no draw it!
I had a similar problem with the icon size and zoom level in my application. What I ended up doing was having 2 sets of overlays containing the markers, one with a "zoomed in" icon and one with a "zoomed out" icon. Then just changed the overlay at a certain zoom level (using a zoom poller - On zoom event for google maps on android)