fix PCTEXT better in dis-laying tunnel files

core/views/drawings.py

@@ -22,6 +22,22 @@ todo='''- Need to check if invalid query string is invalid, or produces multiple
 and render a user-friendly error page.
 '''
 
+def unescape(input):
+    '''These look like HTML entities, but they are not. They are tunnel-specific encodings
+    '''
+    codes = {
+        "&space;" : " ",
+        """ : "\"",
+        "&tab;" : "\t",
+        "&backslash;" : "\\",
+        "&newline;" : "\n\t",
+        "&apostrophe": "'",
+    }
+    for c in codes:
+        #print(c, codes[c])
+        input = input.replace(c, codes[c])
+    return input
+    
 
 def dwgallfiles(request):
     '''Report on all the drawing files in the system. These were loaded by parsing the entire directory tree
@@ -54,10 +70,9 @@ def dwgfilesingle(request, path):
                     print(f'- before reading any {encoding}')
                     lines = f.readlines()
                 #print(f'- finished reading {encoding}')
-                #print(f'- {len(lines)=}')
                 clean = []
                 for l in lines:
-                    clean.append(l.replace('&','@').replace('&','&').replace('@', '&'))
+                    clean.append(unescape(l)) # deals with strangely embedded survex file
                 #print(f'- Cleaned and stripped.')
                 try:
                     return HttpResponse(content=clean, content_type="text/xml")