[OpenLayers-Users] Tile render mechanisms in OL

[maven apache]

Hi:

I am interesting in OpenLayers although we do not use OL in our project
directly  because we have our own library( of course there is a big gap
compared with OL).

Why we do not change to OL is that it may cost too much time to do the
re-build work.

And now the main problem of our library is the performance with more than
one layers added.

For example, I have tried to add 10 layers to an openlayers map, and when I
drag,move,or drog-drop the map, I would not feel any delay while I would
fell it is hardly to drag or move the map with the same operation in our
library.

So I think it may caused by the Tile render mechanisms, and I have tried to
dig in to the source code of OL to find something I have missed.

And I found this in the Grid.js:
initGriddedTiles: function (bounds) {
   ////////
for (var i = 0, ii = tileData.length; i < ii; ++i) {
tileData[i].tile.draw();
 }

}

moveGriddedTiles:function(){
  //
}

And it seems that when the layer is added to the map, the
`initGriddedTiles` will be called, and the tile will be render immediately
since the `....tile.draw()`.

And when the `moveTo()` of map is called, the `moveGriddedTiles` will be
called accordingly.


Then I have two question:

1 So Why the `moveGriddedTiles` method does not render the tile?

And When the map is initialized I found a TileManager instance is created
which will register some event listeners to the map.

It seem that The TileManager will be responsible for tile rendering.

2 So which is the real charger of the tile rendering, the `Layer` or the
`TileManager`?

And I will be appreciate if someone can tell me more about the tile
rendering in OL.

Thanks.
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