Always return a thumbnail of the requested size.

synapse/config/repository.py

@@ -14,6 +14,39 @@
 # limitations under the License.
 
 from ._base import Config
+from collections import namedtuple
+
+ThumbnailRequirement = namedtuple(
+    "ThumbnailRequirement", ["width", "height", "method", "media_type"]
+)
+
+
+def parse_thumbnail_requirements(thumbnail_sizes):
+    """ Takes a list of dictionaries with "width", "height", and "method" keys
+    and creates a map from image media types to the thumbnail size, thumnailing
+    method, and thumbnail media type to precalculate
+
+    Args:
+        thumbnail_sizes(list): List of dicts with "width", "height", and
+            "method" keys
+    Returns:
+        Dictionary mapping from media type string to list of
+        ThumbnailRequirement tuples.
+    """
+    requirements = {}
+    for size in thumbnail_sizes:
+        width = size["width"]
+        height = size["height"]
+        method = size["method"]
+        jpeg_thumbnail = ThumbnailRequirement(width, height, method, "image/jpeg")
+        png_thumbnail = ThumbnailRequirement(width, height, method, "image/png")
+        requirements.setdefault("image/jpeg", []).append(jpeg_thumbnail)
+        requirements.setdefault("image/gif", []).append(png_thumbnail)
+        requirements.setdefault("image/png", []).append(png_thumbnail)
+    return {
+        media_type: tuple(thumbnails)
+        for media_type, thumbnails in requirements.items()
+    }
 
 
 class ContentRepositoryConfig(Config):
@@ -22,6 +55,10 @@ def read_config(self, config):
         self.max_image_pixels = self.parse_size(config["max_image_pixels"])
         self.media_store_path = self.ensure_directory(config["media_store_path"])
         self.uploads_path = self.ensure_directory(config["uploads_path"])
+        self.dynamic_thumbnails = config["dynamic_thumbnails"]
+        self.thumbnail_requirements = parse_thumbnail_requirements(
+            config["thumbnail_sizes"]
+        )
 
     def default_config(self, config_dir_path, server_name):
         media_store = self.default_path("media_store")
@@ -38,4 +75,26 @@ def default_config(self, config_dir_path, server_name):
 
         # Maximum number of pixels that will be thumbnailed
         max_image_pixels: "32M"
+
+        # Whether to generate new thumbnails on the fly to precisely match
+        # the resolution requested by the client. If true then whenever
+        # a new resolution is requested by the client the server will
+        # generate a new thumbnail. If false the server will pick a thumbnail
+        # from a precalcualted list.
+        dynamic_thumbnails: false
+
+        # List of thumbnail to precalculate when an image is uploaded.
+        thumbnail_sizes:
+        - width: 32
+          height: 32
+          method: crop
+        - width: 96
+          height: 96
+          method: crop
+        - width: 320
+          height: 240
+          method: scale
+        - width: 640
+          height: 480
+          method: scale
         """ % locals()

synapse/rest/media/v1/base_resource.py

@@ -69,6 +69,8 @@ def __init__(self, hs, filepaths):
         self.filepaths = filepaths
         self.version_string = hs.version_string
         self.downloads = {}
+        self.dynamic_thumbnails = hs.config.dynamic_thumbnails
+        self.thumbnail_requirements = hs.config.thumbnail_requirements
 
     def _respond_404(self, request):
         respond_with_json(
@@ -208,22 +210,74 @@ def _respond_with_file(self, request, media_type, file_path,
             self._respond_404(request)
 
     def _get_thumbnail_requirements(self, media_type):
-        if media_type == "image/jpeg":
-            return (
-                (32, 32, "crop", "image/jpeg"),
-                (96, 96, "crop", "image/jpeg"),
-                (320, 240, "scale", "image/jpeg"),
-                (640, 480, "scale", "image/jpeg"),
-            )
-        elif (media_type == "image/png") or (media_type == "image/gif"):
-            return (
-                (32, 32, "crop", "image/png"),
-                (96, 96, "crop", "image/png"),
-                (320, 240, "scale", "image/png"),
-                (640, 480, "scale", "image/png"),
+        return self.thumbnail_requirements.get(media_type, ())
+
+    def _generate_thumbnail(self, input_path, t_path, t_width, t_height,
+                            t_method, t_type):
+        thumbnailer = Thumbnailer(input_path)
+        m_width = thumbnailer.width
+        m_height = thumbnailer.height
+
+        if m_width * m_height >= self.max_image_pixels:
+            logger.info(
+                "Image too large to thumbnail %r x %r > %r",
+                m_width, m_height, self.max_image_pixels
             )
+            return
+
+        if t_method == "crop":
+            t_len = thumbnailer.crop(t_path, t_width, t_height, t_type)
+        elif t_method == "scale":
+            t_len = thumbnailer.scale(t_path, t_width, t_height, t_type)
         else:
-            return ()
+            t_len = None
+
+        return t_len
+
+    @defer.inlineCallbacks
+    def _generate_local_exact_thumbnail(self, media_id, t_width, t_height,
+                                        t_method, t_type):
+        input_path = self.filepaths.local_media_filepath(media_id)
+
+        t_path = self.filepaths.local_media_thumbnail(
+            media_id, t_width, t_height, t_type, t_method
+        )
+        self._makedirs(t_path)
+
+        t_len = yield threads.deferToThread(
+            self._generate_thumbnail,
+            input_path, t_path, t_width, t_height, t_method, t_type
+        )
+
+        if t_len:
+            yield self.store.store_local_thumbnail(
+                media_id, t_width, t_height, t_type, t_method, t_len
+            )
+
+            defer.returnValue(t_path)
+
+    @defer.inlineCallbacks
+    def _generate_remote_exact_thumbnail(self, server_name, file_id, media_id,
+                                         t_width, t_height, t_method, t_type):
+        input_path = self.filepaths.remote_media_filepath(server_name, file_id)
+
+        t_path = self.filepaths.remote_media_thumbnail(
+            server_name, file_id, t_width, t_height, t_type, t_method
+        )
+        self._makedirs(t_path)
+
+        t_len = yield threads.deferToThread(
+            self._generate_thumbnail,
+            input_path, t_path, t_width, t_height, t_method, t_type
+        )
+
+        if t_len:
+            yield self.store.store_remote_media_thumbnail(
+                server_name, media_id, file_id,
+                t_width, t_height, t_type, t_method, t_len
+            )
+
+            defer.returnValue(t_path)
 
     @defer.inlineCallbacks
     def _generate_local_thumbnails(self, media_id, media_info):

synapse/rest/media/v1/thumbnail_resource.py

@@ -43,14 +43,25 @@ def _async_render_GET(self, request):
         m_type = parse_string(request, "type", "image/png")
 
         if server_name == self.server_name:
-            yield self._respond_local_thumbnail(
-                request, media_id, width, height, method, m_type
-            )
+            if self.dynamic_thumbnails:
+                yield self._select_or_generate_local_thumbnail(
+                    request, media_id, width, height, method, m_type
+                )
+            else:
+                yield self._respond_local_thumbnail(
+                    request, media_id, width, height, method, m_type
+                )
         else:
-            yield self._respond_remote_thumbnail(
-                request, server_name, media_id,
-                width, height, method, m_type
-            )
+            if self.dynamic_thumbnails:
+                yield self._select_or_generate_remote_thumbnail(
+                    request, server_name, media_id,
+                    width, height, method, m_type
+                )
+            else:
+                yield self._respond_remote_thumbnail(
+                    request, server_name, media_id,
+                    width, height, method, m_type
+                )
 
     @defer.inlineCallbacks
     def _respond_local_thumbnail(self, request, media_id, width, height,
@@ -82,6 +93,87 @@ def _respond_local_thumbnail(self, request, media_id, width, height,
                 request, media_info, width, height, method, m_type,
             )
 
+    @defer.inlineCallbacks
+    def _select_or_generate_local_thumbnail(self, request, media_id, desired_width,
+                                            desired_height, desired_method,
+                                            desired_type):
+        media_info = yield self.store.get_local_media(media_id)
+
+        if not media_info:
+            self._respond_404(request)
+            return
+
+        thumbnail_infos = yield self.store.get_local_media_thumbnails(media_id)
+        for info in thumbnail_infos:
+            t_w = info["thumbnail_width"] == desired_width
+            t_h = info["thumbnail_height"] == desired_height
+            t_method = info["thumbnail_method"] == desired_method
+            t_type = info["thumbnail_type"] == desired_type
+
+            if t_w and t_h and t_method and t_type:
+                file_path = self.filepaths.local_media_thumbnail(
+                    media_id, desired_width, desired_height, desired_type, desired_method,
+                )
+                yield self._respond_with_file(request, desired_type, file_path)
+                return
+
+        logger.debug("We don't have a local thumbnail of that size. Generating")
+
+        # Okay, so we generate one.
+        file_path = yield self._generate_local_exact_thumbnail(
+            media_id, desired_width, desired_height, desired_method, desired_type
+        )
+
+        if file_path:
+            yield self._respond_with_file(request, desired_type, file_path)
+        else:
+            yield self._respond_default_thumbnail(
+                request, media_info, desired_width, desired_height,
+                desired_method, desired_type,
+            )
+
+    @defer.inlineCallbacks
+    def _select_or_generate_remote_thumbnail(self, request, server_name, media_id,
+                                             desired_width, desired_height,
+                                             desired_method, desired_type):
+        media_info = yield self._get_remote_media(server_name, media_id)
+
+        thumbnail_infos = yield self.store.get_remote_media_thumbnails(
+            server_name, media_id,
+        )
+
+        file_id = media_info["filesystem_id"]
+
+        for info in thumbnail_infos:
+            t_w = info["thumbnail_width"] == desired_width
+            t_h = info["thumbnail_height"] == desired_height
+            t_method = info["thumbnail_method"] == desired_method
+            t_type = info["thumbnail_type"] == desired_type
+
+            if t_w and t_h and t_method and t_type:
+                file_path = self.filepaths.remote_media_thumbnail(
+                    server_name, file_id, desired_width, desired_height,
+                    desired_type, desired_method,
+                )
+                yield self._respond_with_file(request, desired_type, file_path)
+                return
+
+        logger.debug("We don't have a local thumbnail of that size. Generating")
+
+        # Okay, so we generate one.
+        file_path = yield self._generate_remote_exact_thumbnail(
+            server_name, file_id, media_id, desired_width,
+            desired_height, desired_method, desired_type
+        )
+
+        if file_path:
+            yield self._respond_with_file(request, desired_type, file_path)
+        else:
+            yield self._respond_default_thumbnail(
+                request, media_info, desired_width, desired_height,
+                desired_method, desired_type,
+            )
+
     @defer.inlineCallbacks
     def _respond_remote_thumbnail(self, request, server_name, media_id, width,
                                   height, method, m_type):