docs: wip document shapelibs

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/docs/shapelibs.rst b/docs/shapelibs.rst
index 4d5ef75fae6dcdf9cb2c698734075e9d8fb2503a..8b0bb031362abde03b607b31fad508c7ebb0aee3 100644 (file)
--- a/docs/shapelibs.rst
+++ b/docs/shapelibs.rst
@@ -179,7 +179,8 @@ Parameters
    ``_s`` is replaced by the sort extra field from the ``files`` list
    ``_c`` is replaced by the colour, if applicable.
 
- * ``orig_size`` [1- or 2-element array]: If specified, the supplied
-   image is first scaled from ``orig_size`` to ``size``.  If both
-   ``size`` and ```orig_size`` are 2 elements, this can scale by
-   different amounts in x and y, distorting the image.
+ * ``orig_size`` [1- or 2-element array, or (default) empty array]: If
+   non-empty, the supplied image is first scaled from ``orig_size``
+   to ``size``.  If both ``size`` and ```orig_size`` are 2 elements,
+   this can scale by different amounts in x and y, distorting the
+   image.