[themes] Add state-dependent themeing

Module themes (only!) can now contain state-specific theme information -
for example, the "battery" module has different states for charging and
discharging, and those can have different prefix and postfix
configurations to indicate what is going on.

bumblebee/modules/battery.py

@@ -11,9 +11,14 @@ class Module(bumblebee.module.Module):
     def data(self):
         with open("/sys/class/power_supply/%s/capacity" % self._battery) as f:
             self._capacity = int(f.read())
-        with open("/sys/class/power_supply/%s/status" % self._battery) as f:
-            self._status = f.read().strip()
 
         return "%02d%%" % self._capacity
 
+    def state(self):
+        with open("/sys/class/power_supply/%s/status" % self._battery) as f:
+            self._status = f.read().strip()
+        if self._status == "Discharging":
+            return "discharging"
+        else:
+            return "charging"
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

bumblebee/theme.py

@@ -17,6 +17,12 @@ class Theme:
         value = self._defaults.get(key, value)
         value = module_theme.get(key, value)
 
+        if hasattr(obj, "state"):
+            state = getattr(obj, "state")()
+            state_theme = module_theme.get("states", {}).get(state, {})
+
+            value = state_theme.get(key, value)
+
         return value
 
     def prefix(self, obj):

bumblebee/themes/default.json

@@ -4,7 +4,15 @@
 		"suffix" : " "
 	},
 	"battery": {
-		"prefix": "bat "
+		"prefix": "bat ",
+		"states": {
+			"charging": {
+				"suffix": "+"
+			},
+			"discharging": {
+				"suffix": "-"
+			}
+		}
 	},
 	"time": {
 	}