extract_metadata: extract basic metadata when slicer is unknown

It is possible to extract some metatdata, such as layer height, from bare gcode script.

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

scripts/extract_metadata.py

@@ -70,6 +70,40 @@ class BaseSlicer(object):
         else:
             return None
 
+    def parse_first_layer_height(self):
+        return None
+
+    def parse_layer_height(self):
+        return None
+
+    def parse_object_height(self):
+        return None
+
+    def parse_filament_total(self):
+        return None
+
+    def parse_estimated_time(self):
+        return None
+
+    def parse_first_layer_bed_temp(self):
+        return None
+
+    def parse_first_layer_extr_temp(self):
+        return None
+
+    def parse_thumbnails(self):
+        return None
+
+class UnknownSlicer(BaseSlicer):
+    def __init__(self, name="Unknown", id_pattern=r""):
+        super(UnknownSlicer, self).__init__(name, id_pattern)
+
+    def parse_first_layer_height(self):
+        return self._parse_min_float(r"G1\sZ\d+\.\d*", self.header_data)
+
+    def parse_object_height(self):
+        return self._parse_max_float(r"G1\sZ\d+\.\d*", self.footer_data)
+
 class PrusaSlicer(BaseSlicer):
     def __init__(self, name="PrusaSlicer", id_pattern=r"PrusaSlicer\s.*\son"):
         super(PrusaSlicer, self).__init__(name, id_pattern)
@@ -175,8 +209,6 @@ class Cura(BaseSlicer):
     def parse_estimated_time(self):
         return self._parse_max_float(r";TIME:.*", self.header_data)
 
-    def parse_thumbnails(self):
-        return None
 
 class Simplify3D(BaseSlicer):
     def __init__(self, name="Simplify3D", id_pattern=r"Simplify3D\(R\)"):
@@ -210,8 +242,6 @@ class Simplify3D(BaseSlicer):
                 total_time += max(t) * multiplier
         return round(total_time, 2)
 
-    def parse_thumbnails(self):
-        return None
 
 class KISSlicer(BaseSlicer):
     def __init__(self, name="KISSlicer", id_pattern=r";\sKISSlicer"):
@@ -243,8 +273,6 @@ class KISSlicer(BaseSlicer):
             time *= 60
         return round(time, 2)
 
-    def parse_thumbnails(self):
-        return None
 
 class IdeaMaker(BaseSlicer):
     def __init__(self, name="IdeaMaker", id_pattern=r"\sideaMaker\s.*,",):
@@ -308,7 +336,8 @@ def extract_metadata(file_path, log):
             if re.search(s.get_id_pattern(), header_data) is not None:
                 slicer = s
                 break
-        if slicer is not None:
+        if slicer is None:
+            slicer = UnknownSlicer()
         metadata['slicer'] = slicer.get_name()
         if size > READ_SIZE * 2:
             f.seek(size - READ_SIZE)
@@ -324,8 +353,6 @@ def extract_metadata(file_path, log):
             result = func()
             if result is not None:
                 metadata[key] = result
-        else:
-            metadata['slicer'] = "Unknown"
     return metadata
 
 def main(path, filename):