previews in browser

3 files changed, 57 insertions, 1 deletions

diff --git a/tagit/utils/__init__.py b/tagit/utils/__init__.py
index 16dcd4d..daa9eab 100644
--- a/tagit/utils/__init__.py
+++ b/tagit/utils/__init__.py
@@ -10,6 +10,7 @@ import typing
 # inner-module imports
 from . import bsfs
 from . import namespaces as ns
+from . import rmatcher
 from . import time as ttime
 from .frame import Frame
 from .shared import * # FIXME: port properly
diff --git a/tagit/utils/namespaces.py b/tagit/utils/namespaces.py
index 5446922..dbdb853 100644
--- a/tagit/utils/namespaces.py
+++ b/tagit/utils/namespaces.py
@@ -19,8 +19,9 @@ bsm = _bsfs.Namespace('http://bsfs.ai/schema/Meta')
 
 # auxiliary bsfs namespaces
 bse = _bsfs.Namespace('http://bsfs.ai/schema/Entity')
-bst = _bsfs.Namespace('http://bsfs.ai/schema/Tag')
 bsg = _bsfs.Namespace('http://bsfs.ai/schema/Group')
+bsp = _bsfs.Namespace('http://bsfs.ai/schema/Preview')
+bst = _bsfs.Namespace('http://bsfs.ai/schema/Tag')
 
 # export
 __all__: typing.Sequence[str] = (
@@ -28,6 +29,7 @@ __all__: typing.Sequence[str] = (
     'bsfs',
     'bsg',
     'bsm',
+    'bsp',
     'bst',
     'xsd',
     )
diff --git a/tagit/utils/rmatcher.py b/tagit/utils/rmatcher.py
new file mode 100644
index 0000000..b5bb802
--- /dev/null
+++ b/tagit/utils/rmatcher.py
@@ -0,0 +1,53 @@
+"""
+
+Part of the tagit module.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# exports
+__all__ = (
+    'by_area',
+    'by_area_min',
+    )
+
+
+## code ##
+
+def by_area(target, candidates):
+    """Pick the item from *candidates* whose area is most similar to *target*."""
+    target_area = target[0] * target[1]
+    scores = [
+        (key, abs(target_area - res[0] * res[1]))
+        for key, res in candidates
+        ]
+    best_key, best_score = min(scores, key=lambda key_score: key_score[1])
+    return best_key
+
+
+def by_area_min(target, candidates):
+    """Pick the item from *candidates* whose area is at least that of *target*."""
+    # rank the candidates by area difference
+    # a positive score means that the candidate is larger than the target.
+    target_area = target[0] * target[1]
+    scores = [(key, res[0] * res[1] - target_area) for key, res in candidates]
+
+    # identify the two items with
+    # a) the smallest positive score (kmin), or
+    # b) the largest negative score (kmax)
+    kmin, kmax = None, None
+    cmin, cmax = float('inf'), float('-inf')
+    for key, score in scores:
+        if score >= 0 and score < cmin:
+            kmin, cmin = key, score
+        elif score < 0 and score > cmax:
+            kmax, cmax = key, score
+
+    # prefer positive over negative scores
+    if cmin < float('inf'):
+        return kmin
+    if cmax > float('-inf'):
+        return kmax
+    # no viable resolution found
+    raise IndexError('list contains no valid element')
+
+## EOF ##