Fix projected line strings getting truncated early.

lib/cartopy/_trace.cpp

@@ -1,5 +1,5 @@
 /*
-# (C) British Crown Copyright 2010 - 2016, Met Office
+# (C) British Crown Copyright 2010 - 2018, Met Office
 #
 # This file is part of cartopy.
 #
@@ -563,7 +563,8 @@ void _project_segment(GEOSContextHandle_t handle,
     t_current = 0.0;
     state = get_state(p_current, gp_domain, handle);
 
-    while(t_current < 1.0 && lines.size() < 500)
+    size_t old_lines_size = lines.size();
+    while(t_current < 1.0 && (lines.size() - old_lines_size) < 100)
     {
         //std::cerr << "Bisecting" << std::endl;
 #ifdef DEBUG

lib/cartopy/tests/test_polygon.py

@@ -18,6 +18,7 @@
 from __future__ import (absolute_import, division, print_function)
 
 import numpy as np
+import pytest
 import shapely.geometry as sgeom
 import shapely.wkt
 
@@ -135,6 +136,50 @@ def test_project_previous_infinite_loop(self):
         src = ccrs.PlateCarree()
         src._attach_lines_to_boundary(multi_line_strings, True)
 
+    @pytest.mark.parametrize('proj',
+                             [ccrs.InterruptedGoodeHomolosine, ccrs.Mollweide])
+    def test_infinite_loop_bounds(self, proj):
+        # test a polygon which used to get stuck in an infinite loop but is now
+        # erroneously clipped.
+        # see https://github.com/SciTools/cartopy/issues/1131
+
+        # These names are for IGH; effectively the same for Mollweide.
+        bottom = [0., 70.]
+        right = [0., 90.]
+        top = [-180., 90.]
+        left = [-180., 70.]
+        verts = np.array([
+            bottom,
+            right,
+            top,
+            left,
+            bottom,
+        ])
+        bad_path = sgeom.Polygon(verts)
+
+        target = proj()
+        source = ccrs.PlateCarree()
+
+        projected = target.project_geometry(bad_path, source)
+
+        # When transforming segments was broken, the resulting path did not
+        # close, and either filled most of the domain, or a smaller portion
+        # than it should. Check that the bounds match the individual points at
+        # the expected edges.
+        projected_left = target.transform_point(left[0], left[1], source)
+        assert projected.bounds[0] == pytest.approx(projected_left[0],
+                                                    rel=target.threshold)
+        projected_bottom = target.transform_point(bottom[0], bottom[1], source)
+        assert projected.bounds[1] == pytest.approx(projected_bottom[1],
+                                                    rel=target.threshold)
+        projected_right = target.transform_point(right[0], right[1], source)
+        assert projected.bounds[2] == pytest.approx(projected_right[0],
+                                                    rel=target.threshold,
+                                                    abs=1e-8)
+        projected_top = target.transform_point(top[0], top[1], source)
+        assert projected.bounds[3] == pytest.approx(projected_top[1],
+                                                    rel=target.threshold)
+
     def test_3pt_poly(self):
         projection = ccrs.OSGB()
         polygon = sgeom.Polygon([(-1000, -1000),