void layer_DataSourceNeeded(object sender, RasterDataSourceEventArgs e)
{
RasterLayer raster = (RasterLayer)(sender);
e.Provider = new GDALRasterProvider(raster.DataProviderParameters["file_name"]);
}
void layer_DataSourceReadyToRelease(object sender, RasterDataSourceEventArgs e)
{
((IDisposable) e.Provider).Dispose();
}
