Merge pull request #25 from takis/issue23

Add an example creating a PDF with metadata, #23

docs/common_use_cases.rst

@@ -179,3 +179,37 @@ Display text
 
   with open('document.pdf', 'wb') as f:
       document.write(f)
+
+
+Add metadata
+------------
+
+.. code-block:: python
+
+    import datetime
+
+    import pydyf
+
+    document = pydyf.PDF()
+    document.info["Author"] = pydyf.String("Jane Doe")
+    document.info["Creator"] = pydyf.String("pydyf")
+    document.info["Keywords"] = pydyf.String("some keywords")
+    document.info["Producer"] = pydyf.String("The producer")
+    document.info["Subject"] = pydyf.String("An example PDF")
+    document.info["Title"] = pydyf.String("A PDF containing metadata")
+    now = datetime.datetime.now()
+    document.info["CreationDate"] = pydyf.String(now.strftime("D:%Y%m%d%H%M%S"))
+
+    document.add_page(
+        pydyf.Dictionary(
+            {
+                "Type": "/Page",
+                "Parent": document.pages.reference,
+                "MediaBox": pydyf.Array([0, 0, 200, 200]),
+            }
+        )
+    )
+
+    # 550 bytes PDF
+    with open("metadata.pdf", "wb") as f:
+        document.write(f)