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Editorial Team
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Asked: 2026-06-06T18:53:59+00:00

I’m using OSMdroid to implement a mapping application. I have implemented a custom MapTileProvider

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I’m using OSMdroid to implement a mapping application.

I have implemented a custom MapTileProvider that uses a tile source that allows zoom levels up to 22.

The default MAPNIK provider only allows zooms to level 18.

The problem is that any PathOverlay instances draw perfectly until zoom level 19, but then
are not drawn properly at zoom level 20-22. it looks like someone’s rubbed out the path with an eraser over 90% of the path length (see screenshots below).

I’ve stepped through the draw() method of PathOverlay and exerything seems to be calculating correctly (the intermediate points appear correct for ZoomLevel 22, and then the XY projections are dividing by 22-ZoomLevel to get current screen coordinates).

Can anyone provide some insight as to what the problem is, and how to resolve it?

The same thing happens if I invoke the MapView using Cloudmade small tiles, which allows zooms up until level 20 and is a ‘built-in’ osmDroid tile provider class.

    //mMapTileProvider = new HighResMapTileProvider(this);
    mMapTileProvider = new MapTileProviderBasic(this,TileSourceFactory.CLOUDMADESMALLTILES);
    mMapView = new MapView(this, 256, mResourceProxy,mMapTileProvider);

So the problem does not appear to be with the tile source or provider but with the canvas drawing method. Any ideas on how to resolve this?

At zoomLevel 19 I can see my paths nicely:
ZoomLevel 19

But here is that same path at the next zoom level:
enter image description here

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1 Answer

  1. Editorial Team

    Update: This has been fixed in osmdroid 3.0.9.

    Original Answer:
    This issue appears to be rooted in Android. I believe it is due to a rounding error that happens when you scroll a view to a large offset (possibly due to use of SKScalar). This bug can be isolated by creating a new android project with an activity and a view:

    1. Begin with the view at the origin with no scroll offset yet.
    2. Draw a circle on the canvas: canvas.drawCircle(screenCenterX, screenCenterY, 100, mPaint)
    3. Scroll the view to a large number: mainView.scrollTo(536870912, 536870912)
    4. Draw a circle on the canvas: canvas.drawCircle(newScreenCenterX, newScreenCenterY, 100, mPaint)

    The first circle draws ok, the second one draws distorted. For further evidence, try to draw your path near 0 lat/0 long and zoom in – notice the distortion no longer appears.

    I will update the osmdroid ticket with some possible solutions workarounds.

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