[pitivi] elements: Change keyframes scale for the volume property

[Alexandru Băluț <alexbalut src gnome org>]

commit 99c073d1fd7df67d726572b3a779539b9e4720a5
Author: Thibault Saunier <tsaunier gnome org>
Date:   Mon Dec 21 12:56:57 2015 +0100

    elements: Change keyframes scale for the volume property
    
    From [0 - 10] to [0 - 2] to make it simpler for users to deal
    with the keyframes UI.
    
    And blacklist the volume effect
    
    Fixes T3076, T3479
    
    Differential Revision: https://phabricator.freedesktop.org/D597

 pitivi/effects.py           |    2 +-
 pitivi/timeline/elements.py |   21 ++++++++++++++++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)
---
diff --git a/pitivi/effects.py b/pitivi/effects.py
index 8c777bd..d312e8d 100644
--- a/pitivi/effects.py
+++ b/pitivi/effects.py
@@ -128,7 +128,7 @@ VIDEO_EFFECTS_CATEGORIES = (
 
 BLACKLISTED_EFFECTS = ["colorconvert", "coglogoinsert", "festival",
                        "alphacolor", "cogcolorspace", "videodetect",
-                       "navigationtest", "videoanalyse"]
+                       "navigationtest", "videoanalyse", "volume"]
 
 # FIXME Check if this is still true with GES
 # We should unblacklist it when #650985 is solved
diff --git a/pitivi/timeline/elements.py b/pitivi/timeline/elements.py
index 16199ae..be35807 100644
--- a/pitivi/timeline/elements.py
+++ b/pitivi/timeline/elements.py
@@ -60,7 +60,23 @@ NORMAL_CURSOR = Gdk.Cursor.new(Gdk.CursorType.LEFT_PTR)
 DRAG_CURSOR = Gdk.Cursor.new(Gdk.CursorType.HAND1)
 
 
+def get_pspec(element_factory_name, propname):
+    element = Gst.ElementFactory.make(element_factory_name)
+    if not element:
+        return None
+
+    return [prop for prop in element.list_properties() if prop.name == propname][0]
+
+
 class KeyframeCurve(FigureCanvas, Loggable):
+    YLIM_OVERRIDES = {}
+
+    __YLIM_OVERRIDES_VALUES = [("volume", "volume", (0.0, 0.2))]
+
+    for factory_name, propname, values in __YLIM_OVERRIDES_VALUES:
+        pspec = get_pspec(factory_name, propname)
+        if pspec:
+            YLIM_OVERRIDES[pspec] = values
 
     __gsignals__ = {
         # Signal our values changed, and a redraw will be needed
@@ -79,6 +95,7 @@ class KeyframeCurve(FigureCanvas, Loggable):
         self.__timeline = timeline
         self.__source = binding.props.control_source
         self.__propertyName = binding.props.name
+        self.__pspec = binding.pspec
         self.__resetTooltip()
 
         # Curve values, basically separating source.get_values() timestamps
@@ -144,7 +161,9 @@ class KeyframeCurve(FigureCanvas, Loggable):
             self.__line_ys.append(value.value)
 
         self.__ax.set_xlim(self.__line_xs[0], self.__line_xs[-1])
-        self.__ax.set_ylim(0.0, 1.0)
+        ylim_min, ylim_max = KeyframeCurve.YLIM_OVERRIDES.get(
+            self.__pspec, (0.0, 1.0))
+        self.__ax.set_ylim(ylim_min, ylim_max)
 
         arr = numpy.array((self.__line_xs, self.__line_ys))
         arr = arr.transpose()