Blurred custom tiles on Android Maps V2

Question

I want to show a CustomOverlay on a Google Maps V2. The loading of the tiles works as expected, the only thing is, that the shown tiles are not appearing to be sharp at all, kin

Answer 1

It's a problem with the zoom level and scaling of the map tiles. This seems to be a problem with the Maps API V2 for Android. The behavior is supposedly intended as stated here: gmaps-api-issues #4840

I solved it by requesting larger tiles from the WMS - just replace 256x256 with 512x512.

Answer 2

I am solving this issue by drawing four tiles into one tile.

I wrote this TileProvider which is using another tile provider to create higher resolution tiles.

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;

import com.google.android.gms.maps.model.Tile;
import com.google.android.gms.maps.model.TileProvider;

import java.io.ByteArrayOutputStream;

public class CanvasTileProvider implements TileProvider {

    static final int TILE_SIZE = 512;
    private TileProvider mTileProvider;

    public CanvasTileProvider(TileProvider tileProvider) {
        mTileProvider = tileProvider;
    }

    @Override
    public Tile getTile(int x, int y, int zoom) {
        byte[] data;
        Bitmap image = getNewBitmap();
        Canvas canvas = new Canvas(image);
        boolean isOk = onDraw(canvas, zoom, x, y);
        data = bitmapToByteArray(image);
        image.recycle();

        if (isOk) {
            Tile tile = new Tile(TILE_SIZE, TILE_SIZE, data);
            return tile;
        } else {
            return mTileProvider.getTile(x, y, zoom);
        }
    }

    Paint paint = new Paint();

    private boolean onDraw(Canvas canvas, int zoom, int x, int y) {
        x = x * 2;
        y = y * 2;
        Tile leftTop = mTileProvider.getTile(x, y, zoom + 1);
        Tile leftBottom = mTileProvider.getTile(x, y + 1, zoom + 1);
        Tile rightTop = mTileProvider.getTile(x + 1, y, zoom + 1);
        Tile rightBottom = mTileProvider.getTile(x + 1, y + 1, zoom + 1);

        if (leftTop == NO_TILE && leftBottom == NO_TILE && rightTop == NO_TILE && rightBottom == NO_TILE) {
            return false;
        }


        Bitmap bitmap;

        if (leftTop != NO_TILE) {
            bitmap = BitmapFactory.decodeByteArray(leftTop.data, 0, leftTop.data.length);
            canvas.drawBitmap(bitmap, 0, 0, paint);
            bitmap.recycle();
        }

        if (leftBottom != NO_TILE) {
            bitmap = BitmapFactory.decodeByteArray(leftBottom.data, 0, leftBottom.data.length);
            canvas.drawBitmap(bitmap, 0, 256, paint);
            bitmap.recycle();
        }
        if (rightTop != NO_TILE) {
            bitmap = BitmapFactory.decodeByteArray(rightTop.data, 0, rightTop.data.length);
            canvas.drawBitmap(bitmap, 256, 0, paint);
            bitmap.recycle();
        }
        if (rightBottom != NO_TILE) {
            bitmap = BitmapFactory.decodeByteArray(rightBottom.data, 0, rightBottom.data.length);
            canvas.drawBitmap(bitmap, 256, 256, paint);
            bitmap.recycle();
        }
        return true;
    }

    private Bitmap getNewBitmap() {
        Bitmap image = Bitmap.createBitmap(TILE_SIZE, TILE_SIZE,
                Bitmap.Config.ARGB_8888);
        image.eraseColor(Color.TRANSPARENT);
        return image;
    }

    private static byte[] bitmapToByteArray(Bitmap bm) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bm.compress(Bitmap.CompressFormat.PNG, 100, bos);

        byte[] data = bos.toByteArray();
        try {
            bos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return data;
    }
}