improve error message when trying to autofill tiny shapes

3 files changed, 52 insertions, 25 deletions

diff --git a/lib/elements/auto_fill.py b/lib/elements/auto_fill.py
index 486243ea..55292212 100644
--- a/lib/elements/auto_fill.py
+++ b/lib/elements/auto_fill.py
@@ -1,7 +1,9 @@
 import math
+import traceback
 
 from shapely import geometry as shgeo
 
+from ..exceptions import InkstitchException
 from ..i18n import _
 from ..stitches import auto_fill
 from ..utils import cache
@@ -156,27 +158,41 @@ class AutoFill(Fill):
         starting_point = self.get_starting_point(last_patch)
         ending_point = self.get_ending_point()
 
-        if self.fill_underlay:
-            stitches.extend(auto_fill(self.underlay_shape,
-                                      self.fill_underlay_angle,
-                                      self.fill_underlay_row_spacing,
-                                      self.fill_underlay_row_spacing,
-                                      self.fill_underlay_max_stitch_length,
+        try:
+            if self.fill_underlay:
+                stitches.extend(auto_fill(self.underlay_shape,
+                                          self.fill_underlay_angle,
+                                          self.fill_underlay_row_spacing,
+                                          self.fill_underlay_row_spacing,
+                                          self.fill_underlay_max_stitch_length,
+                                          self.running_stitch_length,
+                                          self.staggers,
+                                          self.fill_underlay_skip_last,
+                                          starting_point))
+                starting_point = stitches[-1]
+
+            stitches.extend(auto_fill(self.fill_shape,
+                                      self.angle,
+                                      self.row_spacing,
+                                      self.end_row_spacing,
+                                      self.max_stitch_length,
                                       self.running_stitch_length,
                                       self.staggers,
-                                      self.fill_underlay_skip_last,
-                                      starting_point))
-            starting_point = stitches[-1]
-
-        stitches.extend(auto_fill(self.fill_shape,
-                                  self.angle,
-                                  self.row_spacing,
-                                  self.end_row_spacing,
-                                  self.max_stitch_length,
-                                  self.running_stitch_length,
-                                  self.staggers,
-                                  self.skip_last,
-                                  starting_point,
-                                  ending_point))
+                                      self.skip_last,
+                                      starting_point,
+                                      ending_point))
+        except InkstitchException, exc:
+            # for one of our exceptions, just print the message
+            self.fatal(_("Unable to autofill: ") + str(exc))
+        except Exception, exc:
+            # for an uncaught exception, give a little more info so that they can create a bug report
+            message = ""
+            message += _("Error during autofill!  This means that there is a problem with Ink/Stitch.")
+            message += "\n\n"
+            message += _("If you'd like to help us make Ink/Stitch better, please paste this whole message into a new issue at: https://github.com/inkstitch/inkstitch/issues/new")
+            message += "\n\n"
+            message += traceback.format_exc()
+
+            self.fatal(message)
 
         return [Patch(stitches=stitches, color=self.color)]
diff --git a/lib/exceptions.py b/lib/exceptions.py
new file mode 100644
index 00000000..30e595ea
--- /dev/null
+++ b/lib/exceptions.py
@@ -0,0 +1,2 @@
+class InkstitchException(Exception):
+    pass
\ No newline at end of file
diff --git a/lib/stitches/auto_fill.py b/lib/stitches/auto_fill.py
index c7e65473..1c0be0a0 100644
--- a/lib/stitches/auto_fill.py
+++ b/lib/stitches/auto_fill.py
@@ -5,13 +5,18 @@ import sys
 import networkx
 import shapely
 
+from ..exceptions import InkstitchException
 from ..i18n import _
 from ..utils.geometry import Point as InkstitchPoint, cut
 from .fill import intersect_region_with_grating, row_num, stitch_row
 from .running_stitch import running_stitch
 
 
-class MaxQueueLengthExceeded(Exception):
+class MaxQueueLengthExceeded(InkstitchException):
+    pass
+
+
+class InvalidPath(InkstitchException):
     pass
 
 
@@ -55,7 +60,7 @@ def auto_fill(shape,
     rows_of_segments = intersect_region_with_grating(shape, angle, row_spacing, end_row_spacing)
     segments = [segment for row in rows_of_segments for segment in row]
 
-    graph = build_graph(shape, segments, angle, row_spacing)
+    graph = build_graph(shape, segments, angle, row_spacing, max_stitch_length)
     path = find_stitch_path(graph, segments, starting_point, ending_point)
 
     stitches.extend(path_to_stitches(graph, path, shape, angle, row_spacing, max_stitch_length, running_stitch_length, staggers, skip_last))
@@ -90,7 +95,7 @@ def project(shape, coords, outline_index):
     return outline.project(shapely.geometry.Point(*coords))
 
 
-def build_graph(shape, segments, angle, row_spacing):
+def build_graph(shape, segments, angle, row_spacing, max_stitch_length):
     """build a graph representation of the grating segments
 
     This function builds a specialized graph (as in graph theory) that will
@@ -173,8 +178,12 @@ def build_graph(shape, segments, angle, row_spacing):
             if i % 2 == edge_set:
                 graph.add_edge(node1, node2, key="extra")
 
-    if not networkx.is_eulerian(graph):
-        raise Exception(_("Unable to autofill.  This most often happens because your shape is made up of multiple sections that aren't connected."))
+    if networkx.is_empty(graph) or not networkx.is_eulerian(graph):
+        if shape.area < max_stitch_length ** 2:
+            raise InvalidPath(_("This shape is so small that it cannot be filled with rows of stitches.  "
+                                "It would probably look best as a satin column or running stitch."))
+        else:
+            raise InvalidPath(_("Cannot parse shape.  This most often happens because your shape is made up of multiple sections that aren't connected."))
 
     return graph