Debug symbolizer is useful, and used in a bunch of tests. This
adds debug symbolizer support for Cairo to make it closer to the
capabilities of AGG.
Adding debug symbolizer for Cairo meant that red boxes appeared in
many of the visual test outputs. This commit replaces them with
the output, after visual inspection. They should now be closer to
the output of the AGG test cases.
This uses the renderer_common header to do most of the heavy
lifting, but otherwise is very similar to the AGG renderer
implementation.
Add cairo ref images for group symbolizer tests.
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.
This forces offset lines to be aligned to the closest point to
the anchor point on the original line, meaning that they are
aligned where the offset line and original run parallel, or nearly
so.
