Develop Reference

Polygon not is not filling in android mapview

I am trying to draw a filled polygon on a map view in my app. No matter what I have tried it will not draw filled in. I can get the strokes to show up but I can not get it to fill. Below is the draw method of my polygon class. It overrides overlays.
public void draw(Canvas canvas, MapView mapv, boolean shadow) {
super.draw(canvas, mapv, shadow);
Paint mPaint = new Paint();
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setColor(Color.BLACK);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(6);
Paint mPaintFill = new Paint();
mPaintFill.setStyle(Paint.Style.FILL);
mPaintFill.setColor(Color.GREEN);
Path path = new Path();
GeoPoint start = route.get(0);
for (int i = 1; i < route.size(); ++i) {
Point p1 = new Point();
Point p2 = new Point();
Projection projection = mapv.getProjection();
projection.toPixels(start, p1);
projection.toPixels(route.get(i), p2);
path.moveTo(p2.x, p2.y);
path.lineTo(p1.x, p1.y);
start = route.get(i);
}
canvas.drawPath(path, mPaint);
canvas.drawPath(path, mPaintFill);
//canvas.clipPath(path, Op.DIFFERENCE);
}
The above code for me will draw the lines correctly but it doesn't get filled in. Removing canvas.drawPath(path, mPaint); and just leaving the fill one results in nothing showing on the map. I have even tried setting Paint.Style.STROKE to Paint.Style.FILL_AND_STROKE. I am at a complete loss and at this point am thinking it is something simple I am over looking.

Overlay behavior when zooming

I am having trouble with overlays. I have drawn a polygon overlay on the map, however, when I zoom in or out, the edges no longer align with where I want them to. How can I fix this?
Here is what it looks like when I start the app (it covers the whole parking lot perfectly):
Correct
Here is what it looks like when I zoom out (edges no longer line up with parking lot. The overlay looks a bit bigger than the parking lot):
Zoomed out
Also, it doesn't align well when I zoom in. In this case the overlay is a bit smaller that the parking lot. (Sorry, stackoverflow won't let me post more that 2 links)
Any suggestions on how to fix this?
Here is the code:
private Projection projection;
private List<Overlay> mapOverlays;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MapView mapView = (MapView) findViewById(R.id.mapView);
mapView.setBuiltInZoomControls(true);
MapController mc = mapView.getController();
mc.setZoom(17);
mc.animateTo(new GeoPoint((int)(32.734248*1E6), (int)(-97.113448*1E6)));
mapOverlays = mapView.getOverlays();
projection = mapView.getProjection();
mapOverlays.add(new MyOverlay());
mapView.postInvalidate();
}
#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(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setAlpha(100);
GeoPoint gP1 = new GeoPoint(32733839,-97112976);
GeoPoint gP2 = new GeoPoint(32733875, -97113448);
GeoPoint gP3 = new GeoPoint(32734961,-97113455);
GeoPoint gP4 = new GeoPoint(32734953, -97112962);
Point p1 = new Point();
Point p2 = new Point();
Point p3 = new Point();
Point p4 = new Point();
Path path = new Path();
projection.toPixels(gP1, p1);
projection.toPixels(gP2, p2);
projection.toPixels(gP3, p3);
projection.toPixels(gP4, p4);
path.moveTo(p1.x, p1.y);
path.lineTo(p2.x,p2.y);
path.lineTo(p3.x,p3.y);
path.lineTo(p4.x,p4.y);
canvas.drawPath(path, mPaint);
}
}
}

Everytime the zoom changes, Projection also changes. Even when you make a large move in the map without changing zoom, projection may change.
To correct your code you need to add the line as bellow:
public void draw(Canvas canvas, MapView mapv, boolean shadow){
super.draw(canvas, mapv, shadow);
Projection projection = mapv.getProjection(); //Add this line
Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setAlpha(100);
GeoPoint gP1 = new GeoPoint(32733839,-97112976);
GeoPoint gP2 = new GeoPoint(32733875, -97113448);
GeoPoint gP3 = new GeoPoint(32734961,-97113455);
GeoPoint gP4 = new GeoPoint(32734953, -97112962);
Point p1 = new Point();
Point p2 = new Point();
Point p3 = new Point();
Point p4 = new Point();
Path path = new Path();
projection.toPixels(gP1, p1);
projection.toPixels(gP2, p2);
projection.toPixels(gP3, p3);
projection.toPixels(gP4, p4);
path.moveTo(p1.x, p1.y);
path.lineTo(p2.x,p2.y);
path.lineTo(p3.x,p3.y);
path.lineTo(p4.x,p4.y);
canvas.drawPath(path, mPaint);
}
And you can remove the projection created in onCreate().
--EDITED--
Improvements - Quick wins
onDraw() is called twice eveytime you move the map or change zoom level, so it's important to make it as possible. Bellow you can find some suggestions:
private List<Overlay> mapOverlays;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MapView mapView = (MapView) findViewById(R.id.mapView);
mapView.setBuiltInZoomControls(true);
MapController mc = mapView.getController();
mc.setZoom(17);
mc.animateTo(new GeoPoint((int)(32.734248*1E6), (int)(-97.113448*1E6)));
mapOverlays = mapView.getOverlays();
mapOverlays.add(new MyOverlay());
mapView.postInvalidate();
}
#Override
protected boolean isRouteDisplayed() {
return false;
}
class MyOverlay extends Overlay{
//Moved objects that need only one instance to the initialization, to avoid creating a new copy of each every time draw() runs
private Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
private GeoPoint gP1 = new GeoPoint(32733839,-97112976);
private GeoPoint gP2 = new GeoPoint(32733875, -97113448);
private GeoPoint gP3 = new GeoPoint(32734961,-97113455);
private GeoPoint gP4 = new GeoPoint(32734953, -97112962);
private Point p1 = new Point();
private Point p2 = new Point();
private Point p3 = new Point();
private Point p4 = new Point();
private Path path = new Path();
public MyOverlay(){
//mPaint settings done on class creation, to avoid repeating them on draw() call
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setAlpha(100);
}
public void draw(Canvas canvas, MapView mapv, boolean shadow){
super.draw(canvas, mapv, shadow);
//draw is always called twice, one with shadow equal to true and one to false.
//This can be used to draw the same image with shadow
//But you are not using shadows, so you can immediately return half of the calls, and reduce the draw() effort by half
if(shadow) return;
Projection projection = mapv.getProjection();
projection.toPixels(gP1, p1);
projection.toPixels(gP2, p2);
projection.toPixels(gP3, p3);
projection.toPixels(gP4, p4);
path.rewind();
path.moveTo(p1.x,p1.y);
path.lineTo(p2.x,p2.y);
path.lineTo(p3.x,p3.y);
path.lineTo(p4.x,p4.y);
canvas.drawPath(path, mPaint);
}
}
Improvements - a more complex one
The improvement I'm describing bellow is a overkill for you current overlay. It only makes sense when you have realy huge paths to draw.
When you move the map, without zomming it, with the code above the path will be recreated and redrawn in a different place to be aligned with the map. But the path you are creating is the same size, same shape as the previous one, just in a different position.
You can achive the same result using:
path.offset(dx, dy);
where dx, dy is the number of pixels you need to move the path to keep it aligned with the map. Of course, you need to keep track where was the map last time you offset the path, so you can offset the path to the new map position.
If you have a path with several thousands of points, offseting the path will be about 100 times faster then redrawing it.
You also need to keep track on zoom level, as you still need to recreate the path when zoom changes. You can't use getCurrentZoomLevel() to do it, as it´s not synchronized with zoom animation. You need to test longitudeSpan() value changes, to be able to have a synchronized path creation with zoom change animation.
I hope this will help.
Regards.

Android Mapview slows after drawing too much polygon?

I've this custom class that extends the Overlay that is being added into my mapview. i have just one of this class that adds all my polygon and text into this overlay class. However this results in a very slow mapview. I added a draw integer and tested out that this class will draw 84 times each time the ondraw function is being called. Is there any solution that will help to reduce the loading speed of the mapview? Right now the mapview is very slow, each time i move left right or even zoom will be very slow. looking at the android catlog, it seems to me that overlay class ondraw is being called everysecond? should i be looking at another type of layer instead of using overlay?
#Override
public void draw(Canvas canvas, MapView mapView, boolean shadow)
{
shadow=false;
int numberofdraw= 0;
//outline
Paint paint = new Paint();
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStrokeWidth(2);
//paint.setColor(0x10000000);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
paint.setAntiAlias(true);
Point point1_draw = new Point();
for (int i =0;i<data.getCustomPolygonList().size();i++)
{
CustomPolygon customPolygon= data.getCustomPolygonList().get(i);
Path path = new Path();
path.setFillType(Path.FillType.EVEN_ODD);
for(int n=0;n<customPolygon.getCorrdinateList().size();n++)
{
GeoPoint sector1 = new GeoPoint((int)(customPolygon.getCorrdinateList().get(n).getLatitude()*1e6), (int)((customPolygon.getCorrdinateList().get(n).getLongitude())*1e6));
if(n==0){
mapView.getProjection().toPixels(sector1, point1_draw);
path.moveTo(point1_draw.x,point1_draw.y);
}else
{
mapView.getProjection().toPixels(sector1, point1_draw);
path.lineTo(point1_draw.x,point1_draw.y);
}
}
path.close();
canvas.drawPath(path, paint);
numberofdraw++;
// canvas.clipPath(path, Op.DIFFERENCE);
}
//inside sector color
for (int i =0;i<data.getCustomPolygonList().size();i++)
{
CustomPolygon customPolygon= data.getCustomPolygonList().get(i);
paint = new Paint();
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStrokeWidth(2);
paint.setColor(0x186666ff);
//paint.setColor(customPolygon.getColor());
paint.setStyle(Paint.Style.FILL_AND_STROKE);
paint.setAntiAlias(true);
point1_draw = new Point();
Path path = new Path();
path.setFillType(Path.FillType.EVEN_ODD);
for(int n=0;n<customPolygon.getCorrdinateList().size();n++)
{
GeoPoint sector1 = new GeoPoint((int)(customPolygon.getCorrdinateList().get(n).getLatitude()*1e6), (int)((customPolygon.getCorrdinateList().get(n).getLongitude())*1e6));
if(n==0){
mapView.getProjection().toPixels(sector1, point1_draw);
path.moveTo(point1_draw.x,point1_draw.y);
}else
{
mapView.getProjection().toPixels(sector1, point1_draw);
path.lineTo(point1_draw.x,point1_draw.y);
}
}
path.close();
numberofdraw++;
canvas.drawPath(path, paint);
}
//inside sector text
for (int i =0;i<data.getCustomPolygonList().size();i++)
{
CustomPolygon customPolygon= data.getCustomPolygonList().get(i);
TextPaint paintText = new TextPaint();
Point point1 = new Point();
String text=customPolygon.getName();
for(int n=0;n<customPolygon.getCorrdinateList().size();n++)
{
if(customPolygon.getTextLocation()!=null)
{
paintText.setTextSize(24);
Rect rect = new Rect();
paintText.getTextBounds(text, 0, text.length(), rect);
paintText.setTextAlign(Paint.Align.CENTER);
paintText.setTypeface(Typeface.DEFAULT_BOLD);
paintText.setColor(Color.BLACK);
GeoPoint sector1 = new GeoPoint((int)(customPolygon.getTextLocation().getLatitude()*1e6), (int)((customPolygon.getTextLocation().getLongitude())*1e6));
mapView.getProjection().toPixels(sector1, point1);
}
}
numberofdraw++;
canvas.drawText(text, point1.x, point1.y, paintText);
}
Log.e(Config.log_id,"draw no. "+ numberofdraw+"");
}

there are many ways you can improve it, I will suggest you one.
Buffering:
For each polygon create a new canvas and a new bitmap
Canvas myBufferCanvas;
Bitmap myBufferBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
myBufferCanvas = new Canvas(myBufferBitmap);
Then only call draw when the polygon is change, call the draw with myBufferCanvas and then call drawBitmap on the true canvas.
The advantage of this method is performance, it will be extremely fast! The disadvantage is memory, if you have to many polygons, you can kill the device. Just try reusing them some home and you will be fine.
Just remember that you can apply any transformation to your buffered image without redrawing it.

I think you should be using a custom ItemizedOverlay to manage drawing items on your MapView. That aside, there are some changes you can make to your existing code which I'm sure would speed it up. In your draw() method you are creating new Paint objects each time, setting their properties and then disposing of them. Worse still, inside the draw() method you loop through the polygon list twice, creating more Paint objects or TextPaint objects. Instead, you can create one of each Paint object once when the Overlay is initialised and then re-use them in the loop. You may also be able to do everything in one loop.

Process the data, then build the paths and finally paint the paths on the map, see the response from TWiStErRob in this post.

Mapview geopoint is holding screen

I'm having troubles on a simple task.
I'm trying to draw a square at the top left of the map shown below. (top left of the map projection)
But when I convert pixel 0,0 to latitude and longitude with TileSystem (TileSystem.PixelXYToLatLong) the point looks like it is drawn on the screen and not on the map... Why?
The code:
#Override
public void draw(Canvas canvas, MapView mapView, boolean shadow) {
// Translate point to x y coordinates on the screen
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
Point point1_draw = new Point();
Point point2_draw = new Point();
Point point3_draw = new Point();
Point point4_draw = new Point();
mapView.getProjection().toPixels(geoPointFromScreenCoords(0,0,mapView),
point1_draw);
mapView.getProjection().toPixels(geoPointFromScreenCoords(0,100,mapView),
point2_draw);
mapView.getProjection().toPixels(geoPointFromScreenCoords(100,0,mapView),
point3_draw);
mapView.getProjection().toPixels(geoPointFromScreenCoords(100,100,mapView),
point4_draw);
Path path = new Path();
path.setFillType(Path.FillType.EVEN_ODD);
path.moveTo(point1_draw.x, point1_draw.y);
path.lineTo(point2_draw.x, point2_draw.y);
path.lineTo(point3_draw.x, point3_draw.y);
path.lineTo(point4_draw.x, point4_draw.y);
path.lineTo(point1_draw.x, point1_draw.y);
path.close();
//canvas.drawCircle(120, 20, 15, paint);
canvas.drawPath(path, paint);
super.draw(canvas, mapView, false);
}`
I'm extending ItemizedOverlay. And this path is drawn on the screen and not on the map. So when i scrol away this path moves with the map... And I dont want that.

Why are you overriding draw instead of addItem?
Here is a video on how to draw on a map

Android Map Issue?

To show an specific location in android Map, I am using overlay class, and paint object which have reference of Geo point, drawing an balloon bitmap image.
But when I zoom (in/out) map, my balloon does not adjust according to the changed view of the map.
I'm using the following overlay pattern:
class MapOverlay extends com.google.android.maps.Overlay
{
#Override
public void draw(Canvas canvas, MapView mapView, boolean shadow) {
Point point = null, point1 = null;
if(p!=null)
{
point = new Point();
mapView.getProjection().toPixels(p, point);
Bitmap bmp = BitmapFactory.decodeResource(
getResources(), R.drawable.redbaloon);
canvas.drawBitmap(bmp, point.x-38, point.y+60, null);
}}
How can I draw balloon with zooming?