The examples in this folder show how to use the Emscripten generated GDAL library in increasingly complex ways. Ordered from simplest to most complex, they are:

1. inspect_geotiff (Show info about a GeoTIFF, roughly mimicking gdalinfo
2. map_extent (Display the GeoTIFF's extent on a Leaflet map)
3. thumbnail (Generate false-color PNG thumbnail of first three bands of a GeoTIFF)
4. thumbnail_map (Generate false-color PNG thumbnail, warp to EPSG:3857, display on Leaflet map)
5. tile_tiff (Generate false-color PNG map tiles, warp to EPSG:3857, display tile by tile on Leaflet map)

The examples build on each other, but in order to keep them as instructive as possible, they deliberately repeat common elements, rather than pulling them out into wrapper functions. The reason for this is that interacting with Emscripten-generated functions often involves direct access to the Emscripten heap and manipulating pointers, so simply documenting function signatures may not provide a complete picture of how to use a given function. Rather, there is often a significant amount of boilerplate necessary in order to interact with Emscripten functions. The goal of these examples is for each one to provide a standalone picture of how this boilerplate works. Writing a wrapper library would get in the way of demonstrating these core concepts. Much of the code in these examples could form the foundation of a more ergonomic and idiomatic wrapper library, but generating that library is not the purpose of these examples. Rather, it is to document the usage patterns necessary for interacting with the Emscripten-generated GDAL API at the lowest level.

In order to run these examples, make sure that gdal.js, gdal.js.mem, and gdal.data are available from the example directory by building the project (there are symlinks to these locations in the root of the repository for convenience). Then run python server.py from this directory.