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README.md

GEOS Example Programs

  • capi_read uses the standard C API to read two WKT geometries, calculate the intersection and print the result
  • capi_read_ts uses the "re-entrant" C API (threadsafe) to read two WKT geometries, calculate the intersection and print the result
  • capi_prepared uses the standard C API to read one WKT geometry, and fill it with a point grid, applying a high performance "prepared" geometry to speed up intersection testing
  • capi_strtree uses the standard C API to build a random collection of points, and then search that collection quickly to find the nearest to a query point
  • capi_indexed_predicate uses the standard C API API to build an STRtree index on a custom class, and then query that index with a prepared geometry, returning a list of matching items
  • cpp_read uses the C++ API to read two WKT geometries, calculate the intersection and print the result
  • cpp_strtree uses the C++ API to build an STRtree index on a custom class, and then query that index

Build

To build the examples in situ:

mkdir _build
cd _build
cmake ..
make

To build programs in general, you will need to ensure that the appropriate header and include files are available to the compiler. Here's a raw compile command example for a CAPI program:

cc -I/usr/local/include \
    capi_read.c \
    -o capi_read \
    -L/usr/local/lib \
    -lgeos_c
  • Ensure the header files can be found by the compiler
  • Ensure the library files can be found by the compiler
  • Ensure the C API library is passed to the linker

To build a C++ API program, you must pass a define indicating you're OK with the fact that the API will change over time.

c++ -I/usr/local/include -v \
    -std=c++14 \
    -D USE_UNSTABLE_GEOS_CPP_API \
    cpp_read.cpp \
    -o cpp_read \
    -L/usr/local/lib \
    -lgeos