[core] Update only affected widgets on input event

When receiving an input event, only update affected widgets, identified by
their instance ID.

see #353

bumblebee/engine.py

@@ -71,7 +71,7 @@ class Module(object):
                 return widget
 
     def errorWidget(self):
-        msg = self.error
+        msg = self.error or "n/a"
         if len(msg) > 10:
             msg = "{}...".format(msg[0:7])
         return bumblebee.output.Widget(full_text="error: {}".format(msg))
@@ -264,14 +264,32 @@ class Engine(object):
     def run(self):
         """Start the event loop"""
         self._output.start()
+        event = None
         while self.running():
-            self.write_output()
+            if event:
+                self.patch_output(event)
+            else:
+                self.write_output()
             if self.running():
-                self.input.wait(float(self._config.get("interval", 1)))
+                event = self.input.wait(float(self._config.get("interval", 1)))
 
         self._output.stop()
         self.input.stop()
 
+    def patch_output(self, event):
+        for module in self._modules:
+            widget = module.widget_by_id(event["instance"])
+            if not widget: continue
+            # this widget was affected by the event -> update
+            module.update_wrapper(module.widgets())
+            widget = module.errorWidget()
+            if module.error is None:
+                widget = module.widget_by_id(event["instance"])
+            widget.link_module(module)
+            self._output.replace(event, module, widget)
+        self._output.flush()
+        self._output.end()
+
     def write_output(self):
         self._output.begin()
         for module in self._modules:

bumblebee/input.py

@@ -45,6 +45,7 @@ def read_input(inp):
             try:
                 event = json.loads(line)
                 if "instance" in event:
+                    inp.event = event
                     inp.callback(event)
                     inp.redraw()
                 else:
@@ -66,6 +67,7 @@ class I3BarInput(object):
         self.global_id = str(uuid.uuid4())
         self.need_event = False
         self.has_event = False
+        self.event = None
         self._condition = threading.Condition()
 
     def start(self):
@@ -87,6 +89,9 @@ class I3BarInput(object):
 
     def wait(self, timeout):
         self._condition.wait(timeout)
+        rv = self.event if self.has_event else None
+        self.has_event = False
+        return rv
 
     def _wait(self):
         while not self.has_event:

bumblebee/output.py

@@ -105,6 +105,29 @@ class I3BarOutput(object):
         self._started = False
         self._config = config
 
+    def replace(self, event, module, new_widget):
+        full_text = new_widget.full_text()
+        padding = self._theme.padding(new_widget)
+        prefix = self._theme.prefix(new_widget, padding)
+        suffix = self._theme.suffix(new_widget, padding)
+        if prefix:
+            full_text = u"{}{}".format(prefix, full_text)
+        if suffix:
+            full_text = u"{}{}".format(full_text, suffix)
+        separator = self._theme.separator(new_widget)
+        widget_data = {
+            u"full_text": full_text,
+            "color": self._theme.fg(new_widget),
+            "background": self._theme.bg(new_widget),
+            "separator_block_width": self._theme.separator_block_width(new_widget),
+            "separator": True if separator is None else False,
+            "min_width": None,
+            "align": self._theme.align(new_widget),
+            "instance": new_widget.id,
+            "name": module.id,
+        }
+        self._widgets = [w if not "instance" in w or w["instance"] != event["instance"] else widget_data for w in self._widgets]
+
     def started(self):
         return self._started
 

bumblebee/util.py

@@ -20,7 +20,6 @@ def asbool(val):
     return val in ("t", "true", "y", "yes", "on", "1")
 
 def execute(cmd, wait=True):
-    logging.info("executing command '{}'".format(cmd))
     args = shlex.split(cmd)
     proc = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
     rv = None
@@ -35,7 +34,6 @@ def execute(cmd, wait=True):
         else:
             rv = out
 
-    logging.info(u"command returned '{}'".format("" if not rv else rv))
     return rv
 
 def bytefmt(num):