Optimize the download of the tiles about delphi_osmmap

[Fr0sT-Brutal]

the library download all tiles for all zoom number

That's not quite so. Map is smart enough to download only a fragment (current viewport + some border around it). You can check it with demo and a zoom level >=4. But yes, all queued tiles remain even if you change zoom further.

Allow you to change zoom or pan without waiting for the download to finish (now I need wait for it to finish download)

I'm not sure I understand you. Map is completely responsible even if it has no tile image. Do you mean prioritizing tiles to those which fall into current viewport?

if the user change view (zoom and/or pan) while it is downloading tiles, stop the old download (of tiles no longer needed) and download the ones actually needed for the new view

Yep, that's possible and seems not hard to implement

[Fr0sT-Brutal]

The simplest is done, two are in TODO

• Cancel zoom level if another is requested
• Prioritize tile requests to current viewport (additional parameter to TNetworkRequestQueue.RequestTile - but TQueue seems not having a way to do so)
• Only request tiles after scrolling stays for some time (skip requesting all ones which were scrolled by quickly)

[array81]

I'm not sure I understand you. Map is completely responsible even if it has no tile image. Do you mean prioritizing tiles to those which fall into current viewport?

If component download tiles it is difficult to move the map.

[AlexHausauer]

Если Вы хотите, чтобы быстрее загружалась видимая часть карты, то измените в файле "osm.mapcontrol.pas" константы на: CacheImageDefTilesH=1;
CacheImageDefTilesV=1;
CacheMarginSize=1;
Я сделал так, отображает необходимую часть карты значительно быстрее.

[Fr0sT-Brutal]

If component download tiles it is difficult to move the map.

This is weird. Download is almost completely untied with map drawing. It should scroll smoothly regardless of the available tiles displaying stubs instead. What OS you're on? What happens if you disable network (or set non-existing proxy address)?

For now you can shrink the cache as Alex said, this will reduce the number of tiles downloaded for each single view. Later this trick will become less actual (when tile prioritizing is done)

[Fr0sT-Brutal]

@array81 I just checked fast panning with Demo. All glitches come from line Log(Format('Queued request from inet %s', [TileToStr(Tile)])); in TMainForm.mMapDrawTile. Disabling it makes panning smooth, both with already cached tiles and requested from inet.

[Fr0sT-Brutal]

Prioritizing done in 9f6e2dd