Add support for URI transfer function

Currently does nothing except store the URI.

No tests added yet.

tcolour/TransferCharacteristic.py

@@ -199,3 +199,21 @@ def valid(self) -> bool:
 
     def __repr__(self) -> str:
         return "TransferCharacteristicPower(sequence=%r)" % (self.sequence)
+
+class TransferCharacteristicURI(TransferCharacteristic):
+    """A transfer characteristic that references an external file"""
+
+    def __init__(self, URI) -> None:
+        self.URI = URI
+
+    def forward_transfer(self, data):
+        print("ERROR: You didn't think I'd written my own LUT engine yet did you?")
+
+    def inverse_transfer(self,data):
+        print("ERROR: You didn't think I'd written my own LUT engine yet did you?")
+
+    def valid(self) -> bool:
+        return True
+
+    def __repr__(self) -> str:
+        return "TransferCharacteristicURI(URI=%r)" % (self.URI)

tcolour/tcolour.py

@@ -1,6 +1,7 @@
 import yaml
 import Colourimetry
 import TransferCharacteristic
+import uritools
 
 class TColor():
     """Contains a set of known colour spaces. Allows for interacting with and 
@@ -46,7 +47,10 @@ def transfer_charactersitc_from_YAML(self, yaml_input):
                 return TransferCharacteristic.TransferCharacteristicSequence(yaml_input[1]["Sequence"])
 
             elif tc_type == "URI":
-                raise ValueError("Transfer Characteristic type URI not yet supported", yaml_input)
+                if uritools.isuri(yaml_input[1]["URI"]):
+                    return TransferCharacteristic.TransferCharacteristicURI(yaml_input[1]["URI"])
+                else:
+                    raise ValueError("YAML ERROR, invalid URI: ", yaml_input)
 
             else:
                raise ValueError("YAML ERROR, invald Transfer Characteristic type: ", yaml_input)
@@ -118,4 +122,5 @@ def add_colour_space(self, colour_space):
 
     for key, value in config.config.items():
         print(key, value)
+        print()
         pass

tests/files/tcolor_test.yaml

@@ -70,7 +70,7 @@
 - Sonfu Custom InHouse Transfer:
     Transfer Characteristic:
         - Type: URI
-        - URI: Sonfu-1D.spi1d
+        - URI: file:Sonfu-1D.spi1d
 
 # Append aliases to the previous definition
 - sRGB Presentation: