MapView "lite mode" as in Google Maps

[monsieurtanuki]

Issue Type

• Improvement

Description and/or steps/code to reproduce the problem

As mentioned by @AbduazizKayumov in #958, it would be nice to have a lite mode in MapView, similar to GoogleMaps':

A lite mode map is a bitmap image of a map at a specified location and zoom level

[spyhunter99]

i feel like this was requested before. Someone had asked for a mechanism to fetch a specific tile from the cache, would that satisfy this need?

[monsieurtanuki]

@spyhunter99 Rather than just a tile fetch, it's more like "I would like to put MapView snapshots into a ListView or a CardView"
I know that in my app I used some kind of MapView bitmap export (including tiles, markers, polylines, ...).
I believe most of the export part is already coded. We just need to make it easy to use.

And with a nice demo! I'm currently building another demo with all US states and gathered their geo bounding boxes.
A ListView with 50 US states snapshots would be the target demo. Possibly with rounded corners ;)

[pasniak]

I'd use it for thumbnails of locations in #719. Right now I have bitmap but it is a bit off (just part of a point is displayed i.e. just the tile containing the point, not the neighboring tile).

[monsieurtanuki]

A problem might be to know when a MapView is fully rendered and ready to export:

• when are ALL the needed tiles available?
• possible downgraded mode that includes MapTileApproximater?

For the record, when I exported a MapView into a Bitmap in my app, I used View.getDrawingCache(false). Can we do the same with many distinct maps to exports? I don't think so.

[monsieurtanuki]

Working on it...

[monsieurtanuki]

Knowing when all the needed tiles are available is not an issue, a simple loop is enough.

I managed to export a large png from a geo area, but only the tiles.
I didn't have to create a MapView for that.

Now the problem is: should I create a dummy MapView just to use its draw method, and will it work in background mode, even if the MapView is not visible? Or is it possible to ignore the View aspect and draw directly on a Canvas? Of course the additional views like info windows would be ignored...

The problem is that MapView is at the same time a View, a Canvas drawer, a touch listener and - thanks to Android technology - a kind of repository for Context, Resources or Bitmaps.

[monsieurtanuki]

Working again on the subject.

A way to include all kinds of Overlays in the snapshot is to use Projection instead of MapView in method Overlay.draw(Canvas canvas, MapView mapView, boolean shadow).

@spyhunter99 While I'm creating Overlay.draw(Canvas canvas, Projection projection, boolean shadow), wouldn't we be even better off without the "shadow" parameter, which in the code comments seems to be deemed finally useless, cf. DefaultOverlayManager - always pass false, the shadow parameter will be removed in a later version of osmdroid. What do you think about that?

[monsieurtanuki]

@spyhunter99 Forget it, I'll make it more frictionless by creating both Overlay.draw(Canvas canvas, Projection projection, boolean shadow) and Overlay.draw(Canvas canvas, Projection projection), something like:

public void draw(final Canvas pCanvas, final MapView pMapView, final boolean pShadow) {
	if (pShadow) {
		return;
	}
	draw(pCanvas, pMapView.getProjection());
}

public void draw(final Canvas pCanvas, final Projection pProjection, final boolean pShadow) {
	if (pShadow) {
		return;
	}
	draw(pCanvas, pProjection);
}

public void draw(final Canvas c, final Projection pProjection) {}

The (reachable?) goal being for classes extending Overlay to override only draw(Canvas, Projection).

[spyhunter99]

A good compromise for removing the method with the pShadow argument is exactly this. Make a new method without it, deprecate the old one and have the old one call the new one. Then may be few versions down the road, add an annoying log statement, that it will go away, then finally remove it

[monsieurtanuki]

Step 1 was #1245 - merged.

[monsieurtanuki]

Currently working on step 2. The goal is to put map snapshots in a ListView (as ImageViews)

[monsieurtanuki]

Done. I've just PR'ed #1277.

[monsieurtanuki]

Done in #1277. Closed.

[s-ilnar]

Hello, I did not understand how to use this :(
If it’s not difficult for you, tell me, please.
How can I generate images with the image of a track in a RecyclerView?

How can I turn on lite mode?

[monsieurtanuki]

@s-ilnar As stated in #1277, try to find inspiration in SampleMapSnapshot sample class, especially when a MapSnapshot is created.

[s-ilnar]

@monsieurtanuki Thank you!