previewdoc: add correct handling of width/height

themis/fields/__init__.py

@@ -398,3 +398,11 @@ class DocHistoLines(Field):
 
 class PreviewDoc(Field):
     implements(IPreviewDoc, IFromUnicode)
+
+    def __init__(self, **kw):
+        for attr in ('height', 'width'):
+            if kw.get(attr):
+                setattr(self, attr, kw.get('attr'))
+            if attr in kw:
+                del kw[attr]
+        super(PreviewDoc, self).__init__(**kw)