Develop Reference

Drawing routes in Android collapses the device

I'm developing an Android aplication that has to show some "places of interest" on a mapview, along with the device current location. This works well.
Also, in my app, the user could "tap" a "place of interest" marker and the aplication would have to draw a route to that marker.
I used Google Directions api to get the route, along with a polyline decoder to get the GeoPoints between the user and the place. For my testing route, google gives me about 200 different GeoPoints.
So, I have a class like this to add those GeoPoints:
public class RouteOverlay extends Overlay {
private GeoPoint gp1;
private GeoPoint gp2;
private int color;
public RouteOverlay(GeoPoint gp1, GeoPoint gp2, int color) {
this.gp1 = gp1;
this.gp2 = gp2;
this.color = color;
}
#Override
public void draw(Canvas canvas, MapView mapView, boolean shadow) {
Projection projection = mapView.getProjection();
Paint paint = new Paint();
Point point = new Point();
projection.toPixels(gp1, point);
paint.setColor(color);
Point point2 = new Point();
projection.toPixels(gp2, point2);
paint.setStrokeWidth(5);
paint.setAlpha(120);
canvas.drawLine(point.x, point.y, point2.x, point2.y, paint);
super.draw(canvas, mapView, shadow);
}
}
what I do to draw the route is the following:
1) Detect the onClick event to a marker in the map.
2) From that event, I create a new thread, where I make the call to the Google API.
3) Once I have the result, I parse/convert it in a GeoPoint list.
4) Then I call my drawPath method:
private void drawPath(List<GeoPoint> geoPoints, int color) {
mapOverlays.clear();
mapOverlays.add(myLocationOverlay);
mapOverlays.add(itemizedoverlay);
for (int i = 1; i < geoPoints.size(); i++) {
mapOverlays.add(new RouteOverlay(geoPoints.get(i - 1), geoPoints.get(i), color));
}
mapView.postInvalidate();
5) Finally, I return to the UI thread.
This method clears the map overlay list (mapOverlays). Then, adds to the list the current location and the "places of interest" overlays. And, finally, adds the route overlays.
The problem is that, suddenly, works veeery slow and finally crashes. But there is no message in the LogCat. So, I thought that 30 overlays + 1 + more than 200 for the route are too much for the phone to handle. But the tutorials I've seen do it this way so...
Can someone tell me if I do anything wrong?
Thanks in advance.

I figured out what I was doing wrong.
When I called the drawPath function, after obtaining the List of GeoPoints, I made a loop to check the coordinates of each point. Something like
for (int i = 0; i < geoList.size(); i++){
Log.i("GEOPOINT " + i, geoList.get(i).toString());
drawpath(geoList, Color.BLUE);
}
The drawPath function got called N times. So the device crashed. My fault.
Programming at 2:00 am is not good for the code!

How to get latitude and longitude with a custom GeoPointer

I have a GPS map and want to use a custom geopoint (using a my PNG) that when I click on a place in the map returns latitude and longitude.
Searching I have found this code
public void recieveLongClick(MotionEvent ev)
{
Projection p = mapView.getProjection();
GeoPoint geoPoint = p.fromPixels((int) ev.getX(), (int) ev.getY());
// You can now pull lat/lng from geoPoint
}
But I don't know how to use this and how to define a GeoPointer with a custom image that is showed when someone click on a place in the map.

mapview, replace/remove a map pin

This part of code takes some coordinates and draws a tag icon in the map.
private void drawMapLocations(Canvas canvas, MapView mapView) {
Iterator<MapTagLocation> iterator = mapTab.getMapLocations().iterator();
Point screenCoords = new Point();
while (iterator.hasNext()) {
MapTagLocation location = iterator.next();
mapView.getProjection().toPixels(location.getPoint(), screenCoords);
canvas.drawBitmap(tagIcon, screenCoords.x - tagIcon.getWidth() / 2, screenCoords.y - tagIcon.getHeight(), null);
}
}
Now I want to make a method that removes or replace a specific tag in the map. Is there any way?
*The tagIcon is a Bitmap.

Android How to get my MapView's Screen coord? (the visible rect)

How can I get the my MapView's Screen coord to save? (visible rect left-top, and zoomlevel)
I'd like to reload that coords after a while. How can I do that?
Thanks, Leslie

I don't know if you have found an answer to your question, so I'll show you my solution. I've put the following code a subclass of the class MapView.
GeoPoint topLeft = this.getProjection().fromPixels(getLeft(), getTop());
GeoPoint bottomRight = this.getProjection().fromPixels(getRight(), getBottom());
int topLat = topLeft.getLatitudeE6();
int topLng = topLeft.getLongitudeE6();
int bottomLat = bottomRight.getLatitudeE6();
int bottomLng = bottomRight.getLongitudeE6();
I hope it will help you.

You needn't know coordinates of visible area (corners of your MapView). The center of the screen and a zoom level will be enough.
// obtain and persist this values
GeoPoint center = mapView.getMapCenter();
int zoomLevel = mapView.getZoomLevel();
// later restore them when you need
GeoPoint center = ...;
int zoomLevel = ...;
// and init your MapView with this values
MapController controller = mapView.getController();
controller.setZoom(zoomLevel);
controller.animateTo(center);

Efficient Map Overlays in Android Google Map

I want to do the following and am kind of stuck on these for a few days:
I was trying to draw polylines (I have encoded polylines, but have managed to decode those) that move when I move the map.
The only solution that I found was for Geopoints to be transformed into screen coordinates... which won't move if I move the map.
I used HelloItemizedOverlay to add about 150 markers and it gets very very slow.
Any idea what to do? I was thinking about threads (handler).
I was looking for some sort of a timer function that executes a given function periodically, say, every 1 minute or so.
I was also looking for ways to clear the Google map from all the markers/lines, etc.

Answers given below :
1) Here's a solution that I used :
/** Called when the activity is first created. */
private List<Overlay> mapOverlays;
private Projection projection;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
linearLayout = (LinearLayout) findViewById(R.id.zoomview);
mapView = (MapView) findViewById(R.id.mapview);
mapView.setBuiltInZoomControls(true);
mapOverlays = mapView.getOverlays();
projection = mapView.getProjection();
mapOverlays.add(new MyOverlay());
}
#Override
protected boolean isRouteDisplayed() {
return false;
}
class MyOverlay extends Overlay{
public MyOverlay(){
}
public void draw(Canvas canvas, MapView mapv, boolean shadow){
super.draw(canvas, mapv, shadow);
Paint mPaint = new Paint();
mPaint.setDither(true);
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(2);
GeoPoint gP1 = new GeoPoint(19240000,-99120000);
GeoPoint gP2 = new GeoPoint(37423157, -122085008);
Point p1 = new Point();
Point p2 = new Point();
Path path = new Path();
Projection projection.toPixels(gP1, p1);
projection.toPixels(gP2, p2);
path.moveTo(p2.x, p2.y);
path.lineTo(p1.x,p1.y);
canvas.drawPath(path, mPaint);
}
courtesy: Drawing a line/path on Google Maps
2) Here's what worked for me :
createMarkers()
{
for(elem:bigList)
{
GeoPoint geoPoint = new GeoPoint((int)(elem.getLat()*1000000), (int) (elem.getLon()*1000000));
OverlayItem overlayItem = new OverlayItem(geoPoint, elem.getName(), elem.getData());
itemizedOverlay.addOverlay(overlayItem);
}
itemizedOverlay.populateNow();
mapOverlays.add(itemizedOverlay); //outside of for loop
}
and in MyOverlay:
public void addOverlay(OverlayItem overlay)
{
m_overlays.add(overlay);
}
public void populateNow()
{
populate();
}
courtesy: stackoverflow.com unknown link
3) The best way is to use a timer class. A very detailed description of the timer class and how to use it is given at this link :
http://life.csu.edu.au/java-tut/essential/threads/timer.html
4) I used this code :
if(!mapOverlays.isEmpty())
{
mapOverlays.clear();
mapView.invalidate();
}
Hope these answers help atleast one other person. Thanks.

I have the same problem. We are developing an iphone app and an android app at the same time. I have 2500 + map overlays. No problem on iphone; a huge performance hit on android when calling populate() after adding all overlays. (Of course, my first try was to call populate() every time after adding an overlay; a typical mistake due to google's tutorial. Now I am calling populate() just once, after all 2500+ overlays have been added to the ItemizedOverlay.)
So the single populate() call takes over 40 seconds to complete on an htc hero device. I had to put in a busy indicator; no progress bar is possible because we cannot get any information about the progress of populate().
I tried another solution: not use ItemizedOverlay but add overlays by hand, subclassing Overlay. Result: indeed it is much faster to add all those overlays to the map; however, the map becomes unusable due to constant calling of the draw() method on each overlay. In my draw method, I tried to optimize as much as possible; I do not create a bitmap every time. My draw() method looks like this:
public void draw(android.graphics.Canvas canvas, MapView mapView, boolean shadow) {
// our marker bitmap already includes shadow.
// centerPoint is the geopoint where we need to put the marker.
if (!shadow) {
Point point = new Point();
mapView.getProjection().toPixels(centerPoint, point);
canvas.drawBitmap(markerBitmap, point.x, point.y, null);
}
}
Here markerBitmap is precomputed. I don't know what else I could optimize. Is there some kind of populate() call required if we are not using ItemizedOverlay??? I could not find any good answers for that.
Right now I resort to caching the ItemizedOverlay once it has been created in a background thread. This way at least the user does not have to wait every time.

For #2, I don't think you solved anything there. Your hard-to-read code is showing how to put markers on overlay and then, how to add that overlay to the map. That's exactly how I do it. I have map with around 300 hotels and it takes around 5 seconds for Android on my Nexus One to create markers. The whole thing is running inside thread and I guess I will have to do some sort of progress bar to let user know what's going on.
I am working on app that already exists on iPhone and it seems iPhone doesn't have any issues to almost instantaneously draw these 300+ markers. I'll have hard time to explain existence of progress bar to my bosses.
If anybody have idea how to optimize this process... I will be grateful.
Here is my code:
...
for (int m = 0; m < ArrList.size(); m++) {
tName = ArrList.get(m).get("name").toString();
tId = ArrList.get(m).get("id").toString();
tLat = ArrList.get(m).get("lat").toString();;
tLng = ArrList.get(m).get("lng").toString();;
try {
lat = Double.parseDouble(tLat);
lng = Double.parseDouble(tLng);
p1 = new GeoPoint(
(int) (lat * 1E6),
(int) (lng * 1E6));
OverlayItem overlayitem = new OverlayItem(p1, tName, tId);
itemizedoverlay.addOverlay(overlayitem);
} catch (NumberFormatException e) {
Log.d(TAG, "NumberFormatException" + e);
}
}
I know I could save some time by avoiding this String > Double conversion, but I don't feel that would give me significant saving.. or it would?

For your 4th question.... simply use the mapOverlays.clear(); method and all the previous markers will be vanished.
code:
if(!mapOverlays.isEmpty()) {
mapOverlays.clear();
mapView.invalidate();
}

Multiple number of drawable objects can be added to a single Overlay which can then be added to the map. Hence, drawing x number of overlay's for x number of objects wouldnt be necessary unless the objects are of different types. Code snippet..
..
Here, CustomPinPoint is my class which extends ItemizedOverlay<OverlayItem>
CustomPinPoint customPinPoint = new CustomPinPoint(drawable, Main.this);
OverlayItem tempOverLayItem = new OverlayItem(
touchedPoint, "PinPoint", "PintPoint 2"); //Point One
customPinPoint.insertPinPoint(tempOverLayItem);
tempOverLayItem = new OverlayItem(new GeoPoint(
(int)(-27.34498 * 1E6), (int)(153.00724 * 1E6)), "PinPoint",
"PintPoint 2"); //Point Two
customPinPoint.insertPinPoint(tempOverLayItem);
overlayList.add(customPinPoint); //Overlay added only once