add Troubleshoot extension (#465)

adds an extension to help you understand what's wrong with an object and how to fix it, e.g. "invalid" fill shapes

1 files changed, 41 insertions, 0 deletions

diff --git a/lib/elements/validation.py b/lib/elements/validation.py
new file mode 100644
index 00000000..41098922
--- /dev/null
+++ b/lib/elements/validation.py
@@ -0,0 +1,41 @@
+from shapely.geometry import Point as ShapelyPoint
+
+from ..utils import Point as InkstitchPoint
+
+
+class ValidationMessage(object):
+    '''Holds information about a problem with an element.
+
+    Attributes:
+      name - A short descriptor for the problem, such as "dangling rung"
+      description - A detailed description of the problem, such as
+        "One or more rungs does not intersect both rails."
+      position - An optional position where the problem occurs,
+        to aid the user in correcting it.  type: Point or tuple of (x, y)
+      steps_to_solve - A list of operations necessary to solve the problem
+    '''
+
+    # Subclasses will fill these in.
+    name = None
+    description = None
+    steps_to_solve = []
+
+    def __init__(self, position=None):
+        if isinstance(position, ShapelyPoint):
+            position = (position.x, position.y)
+
+        self.position = InkstitchPoint(*position)
+
+
+class ValidationError(ValidationMessage):
+    """A problem that will prevent the shape from being embroidered."""
+    pass
+
+
+class ValidationWarning(ValidationMessage):
+    """A problem that won't prevent a shape from being embroidered.
+
+    The user will almost certainly want to fix the warning, but if they
+    don't, Ink/Stitch will do its best to process the object.
+    """
+    pass