Add plugin: ImageThumblinksPlugin

hyde/ext/plugins/images.py

@@ -361,6 +361,112 @@ def begin_site(self):
                         if match_includes(resource.path):
                             self.thumb(resource, dim1, dim2, prefix, crop_type, preserve_orientation)
 
+
+class ImageThumblinksPlugin(PILPlugin):
+    """
+    Generate thumbnailed links to full size images on-the-fly within documents.
+
+    Markup constructions like
+
+        [[!thumblink|{alt text}|{w?}x{h?}|{media path}]]
+
+    are parsed, where
+
+        w is wanted thumbnail width
+        h is wanted thumbnail height
+
+    according to the definitions in ImageThumbnailsPlugin.thumb(). Those
+    constructions are then replaced by
+
+        [![alt text.]([[!!{thumbnail path}]])]([[!!{media path]]])
+
+    which in turn are parsed by `TextlinksPlugin`, which needs to be loaded
+    _after_ `ImageThumblinksPlugin` in `site.yaml`, to yield a thumbnail image
+    that is linked to the full size image.
+
+    Example:
+
+        [[!thumblink|My dog.|x300|images/img_0001.jpg]]
+
+    is transformed to
+
+        [![My dog.]([[!!images/x300-img_0001.jpg]])]([[!!images/img_0001.jpg]])
+
+    which generates a thumbnail link, width 300 px, to the full size image.
+    """
+
+    # Pattern matcher for `!thumblink` syntax.
+    thumbnail_link = re.compile(r'''
+            \[\[                # [[
+            \!thumblink\|       # [[!thumblink|
+            ([^|]*)\|           # My dog.|
+            (\d*)x(\d*)\|       # x300|
+            ([^\]]*)            # img_0001.jpg
+            \]\]                # ]]
+            ''', re.VERBOSE)
+
+    def __init__(self, site):
+        """Initialize plugin."""
+        super(ImageThumblinksPlugin, self).__init__(site)
+
+    def begin_text_resource(self, resource, text):
+        if not resource.uses_template:
+            # If the resource is not to be templated, do nothing.
+            return text
+
+        def replace_content(match):
+            """
+            Parse thumbnail links, generate thumbnail image and return markup
+            for generating a thumbnailed link to the fullsized image.
+            """
+            self.logger.debug('!thumblink instance found, processing')
+            alt, width, height, fullsize_deploy_path = match.groups(1)
+
+            prefix = '{}x{}-'.format(width, height)
+            # `scale_aspect` (called within `ImageThumblinksPlugin.thumb()`)
+            # chokes on string type width or height. This should preferably be
+            # checked within that function in a future rewrite.
+            width = int(width) if width else None
+            height = int(height) if height else None
+            # Reasonable defaults. It would be possible to expand the argument
+            # handling of !thumblink to incorporate custom values, but I do not
+            # see a real use case.
+            crop_type = 'center'
+            preserve_orientation = False
+
+            relative_image_path = os.path.join(self.site.config.media_root,
+                    fullsize_deploy_path)
+
+            image_resource = self.site.content.\
+                    resource_from_relative_deploy_path(relative_image_path)
+            # Generate thumbnail if it does not exist, based on the naming
+            # scheme.
+            thumbnail_plugin = ImageThumbnailsPlugin(self.site)
+            thumbnail_plugin.thumb(image_resource, width, height, prefix,
+                    crop_type, preserve_orientation)
+
+            thumb_deploy_path = self.thumbnail_deploy_path_from_fullsize(
+                    fullsize_deploy_path, prefix)
+
+            # This needs to be interpreted by TextlinksPlugin afterwards, which
+            # transforms deploy paths correctly.
+            return '[![{}]([[!!{}]])]([[!!{}]])'.format(alt, thumb_deploy_path,
+                    fullsize_deploy_path)
+
+        # `replace_content` is a callback function handle that is executed on
+        # the match object which is only generated by matching rows.
+        return self.thumbnail_link.sub(replace_content, text)
+
+    @staticmethod
+    def thumbnail_deploy_path_from_fullsize(fullsize_path, prefix):
+        """
+        Generate thumbnail link path by splicing the prefix into the file name
+        of the fullsize image link.
+        """
+        dir_path, fullsize_filename = os.path.split(fullsize_path)
+        return os.path.join(dir_path, '{}{}'.format(prefix, fullsize_filename))
+
+
 #
 # JPEG Optimization
 #