Read from map view

Hi

I need to create a python script to add a raster layer to the biggest extent in the map view.

For instance, I zoom into an extent in the map, now the python script must add a raster only to the extent I see in the map view.

In other words I need a python command or code to read the map view data.

Like we have some codes that read from current map, I am looking for some codes to read the mapview "what you see in the map".

I appreciate anybody's help for this issue.

Best regards

Babak