[core] Add decorators library

For now, simply add a decorator that allows for scrolling of text

core/decorators.py

@@ -0,0 +1,36 @@
+import util.format
+
+def scrollable(func):
+    def wrapper(module, widget):
+        text = func(module, widget)
+        if not text:
+            return text
+        width = widget.get('theme.width', util.format.asint(module.parameter('width', 30)))
+        if util.format.asbool(module.parameter('scrolling.makewide', True)):
+            widget.set('theme.minwidth', 'A'*width)
+        if width < 0 or len(text) <= width:
+            return text
+
+        bounce = util.format.asint(module.parameter('scrolling.bounce', 1))
+        scroll_speed = util.format.asint(module.parameter('scrolling.speed', 1))
+        start = widget.get('scrolling.start', -1)
+        direction = widget.get('scrolling.direction', 'right')
+        start += scroll_speed if direction == 'right' else -(scroll_speed)
+
+        if width + start > len(text) + (scroll_speed -1):
+            if bounce:
+                widget.set('scrolling.direction', 'left')
+            else:
+                start = 0
+        elif start <= 0:
+            if bounce:
+                widget.set('scrolling.direction', 'right')
+            else:
+                start = len(text)
+        widget.set('scrolling.start', start)
+        text = text[start:width+start]
+
+        return text
+    return wrapper
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4