The first test shows how an obstacle under the group being displayed
will cause the whole group to not display. Above is an replica of
the same layout using non-grouped symbolizers, which shows that
only the parts which intersect the obstacle will not be drawn.
The second is a line placement test, which just tests placement
of groups on a line with variable spacing.
The third is a test of repeat key in group symbolizer.
The test shows two items with different repeat keys ("foo" and "bar")
and rows of other group symbolizers sensitive to either one. The
reference images show that the "bar"-sensitive rows are displaced
by the "bar" item, but not the "foo" item.
Move a lot of processing into a common process_group_symbolizer function.
Also, extract column collection out of process_group_symbolizer function.
This will reduce duplication needed for other renderers.
Segfault was due to `glyph_position` structs keeping a pointer to
`glyph_info` objects which went out of scope at a different time.
The (rather ugly) fix for the moment is to copy that information
into the thunk object.
Create a group_symbolizer_helper for group placments, and extract some code from
text_symbolizer_helper into a base class to share with group_symbolizer_helper.
Also, move tolerance_iterator into its own header file. Use helper in
process_group_symbolizer to find placement positions.
This renders the saved information from previous calls to the
bounding box extraction code, offset by some amount which should
be determined from running the `placement_finder`. Note that this
doesn't implement that bit, just the rendering.
This is done by creating a fake 'virtual' environment at a fake
point and running the symbolizer render code. The actual render
is saved in a thunk for after the group layout has been done.
This includes XML parsing of group symbolizer and related objects and
process_group_symbolizer method in the AGG renderer. This also includes
code to collect group symbolizer indexed columns, create sub features,
and match them to group rules.
