Thank you for your patience. We found an approach that will fit your scenario.
You can take advantage of the RadMap.LocationRect property. It exposes a method that checks if given coordinates or rectangle is visible on the map. This method is called Contains().
In order to achieve your requirement you can traverse all the pins of the map and check if the location of each one is contained by the viewport (using the Contains() method). Furthermore you can create a collection holding all pins that are currently visible and use that collection to fill your grid.
Please give this approach a try and let us know if you need any further assistance.
Pavel R. Pavlov
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