revert accidentially commits on master branch

Damn, I accidentially committed my last eight changes into the master
branch instead of my feature branch.

List of the reverted commits:
4b175d1
9bf67db
d6d1bbb
49be9fa
246b69d
f2939df
014c460
fd1a6ee

voctogui/lib/audioleveldisplay.py

@@ -1,6 +1,5 @@
 import logging
 import math
-import cairo
 
 
 class AudioLevelDisplay(object):
@@ -22,19 +21,6 @@ def __init__(self, drawing_area):
         # register on_draw handler
         self.drawing_area.connect('draw', self.on_draw)
 
-    # generate gradient from green to yellow to red in logarithmic scale
-    def gradient(self, brightness, darkness, height):
-        # prepare gradient
-        lg = cairo.LinearGradient(0, 0, 0, height)
-        # set gradient stops
-        lg.add_color_stop_rgb(0.0, brightness, darkness, darkness)
-        lg.add_color_stop_rgb(0.22, brightness, brightness, darkness)
-        lg.add_color_stop_rgb(0.25, brightness, brightness, darkness)
-        lg.add_color_stop_rgb(0.35, darkness, brightness, darkness)
-        lg.add_color_stop_rgb(1.0, darkness, brightness, darkness)
-        # return result
-        return lg
-
     def on_draw(self, widget, cr):
         # number of audio-channels
         channels = len(self.levelrms)
@@ -62,41 +48,52 @@ def on_draw(self, widget, cr):
         peak_px = [self.normalize_db(db) * height for db in self.levelpeak]
         decay_px = [self.normalize_db(db) * height for db in self.leveldecay]
 
-        if self.height != height:
-            self.height = height
-            # setup gradients for all level bars
-            self.bg_lg = self.gradient(0.25, 0.0, height)
-            self.rms_lg = self.gradient(1.0, 0.0, height)
-            self.peak_lg = self.gradient(0.75, 0.0, height)
-            self.decay_lg = self.gradient(1.0, 0.5, height)
-
-        # draw all level bars for all channels
-        for channel in range(0, channels):
-            # start-coordinate for this channel
-            x = (channel * channel_width) + (channel * margin)
-
-            # draw background
-            cr.rectangle(x, 0, channel_width, height - peak_px[channel])
-            cr.set_source(self.bg_lg)
-            cr.fill()
-
-            # draw peak bar
-            cr.rectangle(
-                x, height - peak_px[channel], channel_width, peak_px[channel])
-            cr.set_source(self.peak_lg)
-            cr.fill()
-
-            # draw rms bar below
-            cr.rectangle(
-                x, height - rms_px[channel], channel_width,
-                rms_px[channel] - peak_px[channel])
-            cr.set_source(self.rms_lg)
-            cr.fill()
-
-            # draw decay bar
-            cr.rectangle(x, height - decay_px[channel], channel_width, 2)
-            cr.set_source(self.decay_lg)
-            cr.fill()
+        # set the line-width >1, to get a nice overlap
+        cr.set_line_width(2)
+
+        # iterate over all pixels
+        for y in range(0, height):
+
+            # calculate our place in the color-gradient, clamp to 0…1
+            # 0 -> green, 0.5 -> yellow, 1 -> red
+            color = self.clamp(((y / height) - 0.6) / 0.42)
+
+            for channel in range(0, channels):
+                # start-coordinate for this channel
+                x = (channel * channel_width) + (channel * margin)
+
+                # calculate the brightness based on whether this line is in the
+                # active region
+
+                # default to 0.25, dark
+                bright = 0.25
+                if int(y - decay_px[channel]) in range(0, 2):
+                    # decay marker, 2px wide, extra bright
+                    bright = 1.5
+                elif y < rms_px[channel]:
+                    # rms bar, full bright
+                    bright = 1
+                elif y < peak_px[channel]:
+                    # peak bar, a little darker
+                    bright = 0.75
+
+                # set the color with a little reduced green
+                cr.set_source_rgb(
+                    color * bright,
+                    (1 - color) * bright * 0.75,
+                    0
+                )
+
+                # draw the marker
+                cr.move_to(x, height - y)
+                cr.line_to(x + channel_width, height - y)
+                cr.stroke()
+
+                # draw a black line for the margin
+                cr.set_source_rgb(0, 0, 0)
+                cr.move_to(x + channel_width, height - y)
+                cr.line_to(x + channel_width + margin, height - y)
+                cr.stroke()
 
             # draw medium grey margin bar
             if margin > 0: