Thank you. This is nice to have.

In the future, we should have another way to build the grid image step by step by adding tiles one by one, but this is a nice convenience function that can still come in handy.

Great, thanks for merging.

I also wanted a mechanism for encoding grids that are internal to the codec (for example, the uncompressed codec). But I wasn't sure what the best way to do this was.

I also wanted a mechanism for encoding grids that are internal to the codec (for example, the uncompressed codec). But I wasn't sure what the best way to do this was.

Interesting question.
@bradh: Would it be possible to write uncompressed image tiles one by one? Does that pose any problems when the data is zlib compressed?

It should be possible to write tiles one-by-one. There is a way to say "each of these extents needs to be done separately", and to specify the range. That opens up the possibility to recycle the bits in one tile that is used to fill many grid spots (e.g. when using a map, and there is a lot of blue ocean; or when making black fill tiles for an image that is rotated to be north-up).