example: add slider volume for audio examples. Refs #1869

examples/audio/audio.kv

@@ -32,6 +32,16 @@
 		font_size: 32
 		size_hint_y: None
 
+	BoxLayout:
+		Slider:
+			min: 0.0
+			max: 1.0
+			value: 1.0
+			on_value: app.set_volume(self.value)
+			orientation: "vertical"
+			size_hint_x: None
+			width: "48dp"
+
 		StackLayout:
 			id: sl
 
@@ -40,4 +50,3 @@
 		size_hint_y: None
 		height: '50sp'
 		on_press: app.release_audio()
-

examples/audio/main.py

@@ -14,7 +14,7 @@ from kivy.app import App
 from kivy.uix.button import Button
 from kivy.uix.boxlayout import BoxLayout
 from kivy.core.audio import SoundLoader
-from kivy.properties import StringProperty, ObjectProperty
+from kivy.properties import StringProperty, ObjectProperty, NumericProperty
 from glob import glob
 from os.path import dirname, join, basename
 
@@ -23,6 +23,7 @@ class AudioButton(Button):
 
     filename = StringProperty(None)
     sound = ObjectProperty(None, allownone=True)
+    volume = NumericProperty(1.0)
 
     def on_press(self):
         if self.sound is None:
@@ -30,6 +31,7 @@ class AudioButton(Button):
         # stop the sound if it's currently playing
         if self.sound.status != 'stop':
             self.sound.stop()
+        self.sound.volume = self.volume
         self.sound.play()
 
     def release_audio(self):
@@ -38,6 +40,11 @@ class AudioButton(Button):
             self.sound.unload()
             self.sound = None
 
+    def set_volume(self, volume):
+        self.volume = volume
+        if self.sound:
+            self.sound.volume = volume
+
 
 class AudioBackground(BoxLayout):
     pass
@@ -61,5 +68,9 @@ class AudioApp(App):
         for audiobutton in self.root.ids.sl.children:
             audiobutton.release_audio()
 
+    def set_volume(self, value):
+        for audiobutton in self.root.ids.sl.children:
+            audiobutton.set_volume(value)
+
 if __name__ == '__main__':
     AudioApp().run()