Release audio/video on visibility change (OLPC#10659)

When visibility is lost, stop recording, live feeds, countdowns, etc.
Allows multiple camera-using apps to run simultaenously.

This doesn't quite work correctly, having 2 Records open and switching
from one to the other doesn't work as expected. Perhaps the events
are being delivered without strict order, or not enough time is being
given to the old Record to release its resources before activating the
new one.

1 files changed, 33 insertions, 4 deletions

diff --git a/model.py b/model.py
index a6d06cb..884325b 100644
--- a/model.py
+++ b/model.py
@@ -55,12 +55,13 @@ class Model:
         self.gplay.connect('playback-status-changed', self._playback_status_changed)
 
         self._mode = None
-        self._state = constants.STATE_READY
+        self._state = constants.STATE_INVISIBLE
         self._countdown_value = 0
         self._countdown_handle = None
         self._timer_value = 0
         self._timer_duration = 0
         self._timer_handle = None
+        self._visible = False
 
         self.mediaHashs = {}
         for key, value in constants.MEDIA_INFO.items():
@@ -116,13 +117,38 @@ class Model:
         self.activity.set_mode(mode)
         self.set_state(constants.STATE_READY)
 
-        if mode == constants.MODE_PHOTO:
-            self.glive.play()
-
     def ui_frozen(self):
         return not self._state == constants.STATE_READY 
 
+    def set_visible(self, visible):
+        if visible == self._visible:
+            return
+
+        self._visible = visible
+
+        if visible:
+            self.set_state(constants.STATE_READY)
+            return
+
+        if self._countdown_handle:
+            gobject.source_remove(self._countdown_handle)
+            self._countdown_handle = None
+            self._countdown_value = 0
+            self.activity.set_countdown(0)
+
+        # Change from visible to invisible.
+        if self._state == constants.STATE_RECORDING:
+            # If recording, stop.
+            self._stop_media_capture()
+        else:
+            self.set_state(constants.STATE_INVISIBLE)
+
     def set_state(self, state):
+        # Never go into READY mode if we aren't visible.
+        if state == constants.STATE_READY and not self._visible:
+            logging.debug("state: overriding READY to INVISIBLE")
+            state = constants.STATE_INVISIBLE
+
         self._state = state
 
         if state == constants.STATE_READY:
@@ -135,6 +161,9 @@ class Model:
                 self.glive.stop()
 
             self.glive.play()
+        elif state == constants.STATE_INVISIBLE:
+            self.gplay.stop()
+            self.glive.stop()
 
         self.activity.set_state(state)