Add a media/v1/identicon resource for generating identicons using pydenticon

setup.py

@@ -43,6 +43,7 @@ setup(
         "py-bcrypt",
         "frozendict>=0.4",
         "pillow",
+        "pydenticon",
     ],
     dependency_links=[
         "https://github.com/matrix-org/syutil/tarball/v0.0.2#egg=syutil-0.0.2",

synapse/rest/media/v1/identicon_resource.py

@@ -0,0 +1,48 @@
+from pydenticon import Generator
+from twisted.web.resource import Resource
+
+FOREGROUND = [
+    "rgb(45,79,255)",
+    "rgb(254,180,44)",
+    "rgb(226,121,234)",
+    "rgb(30,179,253)",
+    "rgb(232,77,65)",
+    "rgb(49,203,115)",
+    "rgb(141,69,170)"
+]
+
+BACKGROUND = "rgb(224,224,224)"
+SIZE = 5
+
+
+class IdenticonResource(Resource):
+    isLeaf = True
+
+    def __init__(self):
+        Resource.__init__(self)
+        self.generator = Generator(
+            SIZE, SIZE, foreground=FOREGROUND, background=BACKGROUND,
+        )
+
+    def generate_identicon(self, name, width, height):
+        v_padding = width % SIZE
+        h_padding = height % SIZE
+        top_padding = v_padding // 2
+        left_padding = h_padding // 2
+        bottom_padding = v_padding - top_padding
+        right_padding = h_padding - left_padding
+        width -= v_padding
+        height -= h_padding
+        padding = (top_padding, bottom_padding, left_padding, right_padding)
+        identicon = self.generator.generate(
+            name, width, height, padding=padding
+        )
+        return identicon
+
+    def render_GET(self, request):
+        name = "/".join(request.postpath)
+        width = int(request.args.get("width", 96))
+        height = int(request.args.get("width", 96))
+        identicon_bytes = self.generate_identicon(name, width, height)
+        request.setHeader(b"Content-Type", b"image/png")
+        return identicon_bytes

synapse/rest/media/v1/media_repository.py

@@ -16,6 +16,7 @@
 from .upload_resource import UploadResource
 from .download_resource import DownloadResource
 from .thumbnail_resource import ThumbnailResource
+from .identicon_resource import IdenticonResource
 from .filepath import MediaFilePaths
 
 from twisted.web.resource import Resource
@@ -75,3 +76,4 @@ class MediaRepositoryResource(Resource):
         self.putChild("upload", UploadResource(hs, filepaths))
         self.putChild("download", DownloadResource(hs, filepaths))
         self.putChild("thumbnail", ThumbnailResource(hs, filepaths))
+        self.putChild("identicon", IdenticonResource())