fix: Update docs (#128)

* fix: Docs

* fix: Clean up repeat

* fix: Typo

Author: tmathern

docs/usage.md

@@ -12,7 +12,7 @@ Import the objects needed from the API:
 from c2pa import Builder, Reader, Signer, C2paSigningAlg, C2paSignerInfo
 ```
 
-You can use both `Builder` and `Reader` classes with context managers by using a `with` statement.
+You can use both `Builder`, `Reader` and `Signer` classes with context managers by using a `with` statement.
 Doing this is recommended to ensure proper resource and memory cleanup.
 
 ## Define manifest JSON
@@ -25,13 +25,15 @@ manifest_json = json.dumps({
     "claim_generator": "python_test/0.1",
     "assertions": [
     {
-      "label": "c2pa.training-mining",
+      "label": "cawg.training-mining",
       "data": {
         "entries": {
-          "c2pa.ai_generative_training": { "use": "notAllowed" },
-          "c2pa.ai_inference": { "use": "notAllowed" },
-          "c2pa.ai_training": { "use": "notAllowed" },
-          "c2pa.data_mining": { "use": "notAllowed" }
+          "cawg.ai_inference": {
+            "use": "notAllowed"
+          },
+          "cawg.ai_generative_training": {
+            "use": "notAllowed"
+          }
         }
       }
     }
@@ -62,7 +64,7 @@ try:
         manifest = json.loads(reader.json())
         active_manifest = manifest["manifests"][manifest["active_manifest"]]
         if active_manifest:
-            # get the uri to the manifest's thumbnail and write it to a file
+            # Get the uri to the manifest's thumbnail and write it to a file
             uri = active_manifest["thumbnail"]["identifier"]
             with open("thumbnail_v2.jpg", "wb") as f:
                 reader.resource_to_stream(uri, f)
@@ -106,7 +108,7 @@ try:
             with open("path/to/source.jpg", "rb") as source_file, open("path/to/output.jpg", "wb") as dest_file:
                 manifest_bytes = builder.sign(signer, "image/jpeg", source_file, dest_file)
 
-            # Verify the signed file
+        # Verify the signed file by reading data from the signed output file
         with Reader("path/to/output.jpg") as reader:
             manifest_store = json.loads(reader.json())
             active_manifest = manifest_store["manifests"][manifest_store["active_manifest"]]
@@ -126,13 +128,13 @@ Instead of working with files, you can read, validate, and add a signed manifest
 try:
     # Create a reader from a format and stream
     with open("path/to/media_file.jpg", "rb") as stream:
-        # First parameter can be mimetype or extension of the file
+        # First parameter should be the type of the file (here, we use the mimetype)
         # But in any case we need something to identify the file type
         with Reader("image/jpeg", stream) as reader:
             # Print manifest store as JSON, as extracted by the Reader
             print("manifest store:", reader.json())
 
-            # Get the active manifest.
+            # Get the active manifest
             manifest = json.loads(reader.json())
             active_manifest = manifest["manifests"][manifest["active_manifest"]]
             if active_manifest:
@@ -158,22 +160,23 @@ try:
         cert_data = cert_file.read()
         key_data = key_file.read()
 
-        # Create signer info
+        # Create signer info using the read certificate and key data
         signer_info = C2paSignerInfo(
             alg=C2paSigningAlg.PS256,
             cert=cert_data,
             key=key_data,
             timestamp_url="http://timestamp.digicert.com"
         )
 
-        # Create signer using the defined SignerInfo
+        # Create a Signer using the SignerInfo defined previously
         signer = Signer.from_info(signer_info)
 
-        # Create builder with manifest and add ingredients
+        # Create a Builder with manifest and add ingredients
         with Builder(manifest_json) as builder:
-            # Add any ingredients if needed
+            # Add any ingredients as needed
             with open("path/to/ingredient.jpg", "rb") as ingredient_file:
                 ingredient_json = json.dumps({"title": "Ingredient Image"})
+                # Here the ingredient is added using streams
                 builder.add_ingredient(ingredient_json, "image/jpeg", ingredient_file)
 
             # Sign using streams
@@ -182,6 +185,7 @@ try:
 
             # Verify the signed file
             with open("path/to/output.jpg", "rb") as stream:
+                # Create a Reader to read data
                 with Reader("image/jpeg", stream) as reader:
                     manifest_store = json.loads(reader.json())
                     active_manifest = manifest_store["manifests"][manifest_store["active_manifest"]]

tests/test_unit_tests.py

@@ -95,6 +95,13 @@ def test_reader_double_close(self):
             with self.assertRaises(Error):
                 reader.json()
 
+    def test_reader_streams_with_nested(self):
+        with open(self.testPath, "rb") as file:
+            with Reader("image/jpeg", file) as reader:
+                manifest_store = json.loads(reader.json())
+                title = manifest_store["manifests"][manifest_store["active_manifest"]]["title"]
+                self.assertEqual(title, DEFAULT_TEST_FILE_NAME)
+
     def test_reader_close_cleanup(self):
         """Test that close properly cleans up all resources."""
         with open(self.testPath, "rb") as file: