improved robustness during file opening in STLImporter

check for file existence during "Load Model" (including error dialog)
 * fixed bug: http://sourceforge.net/tracker/index.php?func=detail&aid=2973875&group_id=237831&atid=1104176


git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@263 bbaffbd6-741e-11dd-a85d-61de82d9cad9

pycam/Gui/Project.py

@@ -1104,6 +1104,8 @@ class ProjectGui:
             self.load_processing_settings(filename)
 
     def load_model(self, model):
+        # load the new model only if the import worked
+        if not model is None:
             self.model = model
             # place the "safe height" clearly above the model's peak
             self.settings.set("safety_height", (2 * self.model.maxz - self.model.minz))
@@ -1474,6 +1476,14 @@ class ProjectGui:
                 response = overwrite_window.run()
                 overwrite_window.destroy()
                 done = (response == gtk.RESPONSE_YES)
+            elif mode_load and not os.path.isfile(filename):
+                not_found_window = gtk.MessageDialog(self.window, type=gtk.MESSAGE_ERROR,
+                        buttons=gtk.BUTTONS_OK,
+                        message_format="This file does not exist. Please choose a different filename.")
+                not_found_window.set_title("Invalid filename selected")
+                response = not_found_window.run()
+                not_found_window.destroy()
+                done = False
             else:
                 done = True
         dialog.destroy()

pycam/Importers/STLImporter.py

-import re, os
-from struct import unpack 
-
 from pycam.Geometry import *
 from pycam.Geometry.PointKdtree import PointKdtree
 from pycam.Geometry.TriangleKdtree import TriangleKdtree
 
+from struct import unpack 
+import re
+import os
+import sys
+
 vertices = 0
 edges = 0
 epsilon = 0.0001
@@ -50,7 +52,11 @@ def ImportModel(filename, use_kdtree=True):
     edges = 0
     kdtree = None
 
+    try:
         f = open(filename,"rb")
+    except IOError, err_msg:
+        print >>sys.stderr, "Failed to read file (%s): %s" % (filename, err_msg)
+        return None
     # read the first two lines of (potentially non-binary) input - they should contain "solid" and "facet"
     header = f.readline(200)
     header += f.readline(200)