Hi,

in response to the discussion of today's team meeting, I added some
tuning options to MapPaneOL:

- tileGutter: sets the OpenLayers gutter option for WMS layers. This
is for specifying overlapping areas of neighboring map tiles. This has
no impact on performance, but should be set to a value of around 10
for better rendering results at tile borders.

- tileBuffer: sets the OpenLayers buffer option for WMS layers. This
specifies how many rows of tiles should be prefetched around the
visible map area. Setting this to a value of 1 will increase
performance for WMS-C layers in Mapbuilder.

- tileSize: lets you specify the size of map tiles. If you have a fast
WMS, larger tiles can be an advantage.

- imageBuffer: this is for OpenLayers Untiled WMS layers and defines
how many times of the visible map area the loaded map image should be.
Setting this to 1 makes MapPaneOL behave like MapPane and MapPane2 -
it loads Mapbuilder WMS layer images exactly as large as the visible
map area. This gives the best performance for WMS layers, but forces a
redraw after every pan operation.

- displayOutsideMapExtent: specifies whether or not layer portions
outside of the map extent should be rendered.


Performance and rendering tips:

- If you want MapPaneOL to do fast refreshes, do not use WMS-C layers
and specify <imageBuffer>1</imageBuffer>.

- If you want to have fast panning response, try to get your map from
a single WMS source and use WMS-C layers. Adjust <tileBuffer> to a
lower value if you do more zooming than panning, and to a higher value
if you usually only do pan operations. Play around with the
<tileGutter> parameter to optimize rendering of lines and polygons
near tile edges.

- If you have long text labels, WMS-C is not the way to go. Use a
transparent WMS layer with eg. <imageBuffer>3</imageBuffer> to load a
large area of labels, and put all other information in a WMS-C layer
below.

Regards,
Andreas.

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