From b9f147f3f72f0ce0eecf7e6598cad4b785aa4719 Mon Sep 17 00:00:00 2001
From: Walter Bender <walter@sugarlabs.org>
Date: Wed, 29 Dec 2010 17:03:42 +0000
Subject: refactored camera code to use poll for MESSAGE_EOS instead of timeout

---
(limited to 'TurtleArt')

diff --git a/TurtleArt/tacamera.py b/TurtleArt/tacamera.py
index a4227ed..2177288 100644
--- a/TurtleArt/tacamera.py
+++ b/TurtleArt/tacamera.py
@@ -22,14 +22,21 @@
 
 import gst, time
 
-def save_camera_input_to_file(imagepath, pause=2.0):
-   """ Grab a frame from the video camera and save to a temporary file """
+GST_PIPE = ['v4l2src', 'ffmpegcolorspace', 'pngenc']
 
-   pipeline = gst.parse_launch(
-      'v4l2src ! ffmpegcolorspace ! jpegenc ! filesink location=' + imagepath)
-   pipeline.set_state(gst.STATE_PLAYING)
+class Camera():
+    """ A class for representing the video camera """
 
-   # Need to pause for pipeline to stablize
-   time.sleep(pause)
+    def __init__(self, imagepath):
+       GST_PIPE.append('filesink location=%s' % imagepath)
+       self.pipe = gst.parse_launch('!'.join(GST_PIPE))
+       self.bus = self.pipe.get_bus()
+
+    def save_camera_input_to_file(self):
+        """ Grab a frame from the camera """
+        self.pipe.set_state(gst.STATE_PLAYING)
+        self.bus.poll(gst.MESSAGE_EOS, -1)
+
+    def stop_camera_input(self):
+        self.pipe.set_state(gst.STATE_NULL)
 
-   pipeline.set_state(gst.STATE_NULL)
diff --git a/TurtleArt/talogo.py b/TurtleArt/talogo.py
index 399b5b4..5c8a771 100755
--- a/TurtleArt/talogo.py
+++ b/TurtleArt/talogo.py
@@ -44,7 +44,7 @@ from taconstants import TAB_LAYER, BLACK, WHITE, \
     SENSOR_DC_BIAS, XO1, XO15
 from tagplay import play_audio_from_file, play_movie_from_file, stop_media, \
     media_playing
-from tacamera import save_camera_input_to_file
+from tacamera import Camera
 from tajail import myfunc, myfunc_import
 from tautils import get_pixbuf_from_journal, convert, data_from_file, \
     text_media_type, round_int, chr_to_ord, strtype, get_path
@@ -305,6 +305,8 @@ def stop_logo(tw):
     tw.step_time = 0
     tw.lc.step = _just_stop()
     stop_media(tw.lc)
+    if tw.camera_available:
+        tw.lc.camera.stop_camera_input()
     tw.active_turtle.show()
 
 
@@ -526,19 +528,17 @@ class LogoCode:
         if self.tw.hw == XO1:
             self.voltage_gain = 0.00002225
             self.voltage_bias = 1.140
-            self.camera_pause = 0.6
         elif self.tw.hw == XO15:
             self.voltage_gain = -0.0001471
             self.voltage_bias = 1.695
-            self.camera_pause = 0.5
-        else:
-            self.camera_pause = 2.0
 
-        if self.tw.running_sugar:
-            self.imagepath = get_path(self.tw.activity,
-                                      'data/turtlepic.jpg')
-        else:
-            self.imagepath = '/tmp/turtlepic.jpg'
+        if self.tw.camera_available:
+            if self.tw.running_sugar:
+                self.imagepath = get_path(self.tw.activity,
+                                          'data/turtlepic.png')
+            else:
+                self.imagepath = '/tmp/turtlepic.png'
+            self.camera = Camera(self.imagepath)
 
     def _def_prim(self, name, args, fcn, rprim=False):
         """ Define the primitives associated with the blocks """
@@ -1327,9 +1327,9 @@ class LogoCode:
                 self.filepath = None
                 dsobject = None
                 if string[6:] == 'CAMERA':
-                    if self.tw.camera:
-                        save_camera_input_to_file(self.imagepath,
-                                                  self.camera_pause)
+                    if self.tw.camera_available:
+                        self.camera.save_camera_input_to_file()
+                        self.camera.stop_camera_input()
                         self.filepath = self.imagepath
                 elif os.path.exists(string[6:]):  # is it a path?
                     self.filepath = string[6:]
@@ -1476,8 +1476,9 @@ class LogoCode:
         array = None
         w = self._w()
         h = self._h()
-        if w > 0 and h > 0 and self.tw.camera:
-            save_camera_input_to_file(self.imagepath, self.camera_pause)
+        if w > 0 and h > 0 and self.tw.camera_available:
+            self.camera.save_camera_input_to_file()
+            self.camera.stop_camera_input()
             pixbuf = gtk.gdk.pixbuf_new_from_file_at_size(self.imagepath, w, h)
             try:
                 array = pixbuf.get_pixels()
diff --git a/TurtleArt/tawindow.py b/TurtleArt/tawindow.py
index a063a2d..ba5b5cf 100755
--- a/TurtleArt/tawindow.py
+++ b/TurtleArt/tawindow.py
@@ -249,11 +249,6 @@ class TurtleArtWindow():
         CONSTANTS['width'] = int(self.canvas.width / self.coord_scale)
         CONSTANTS['height'] = int(self.canvas.height / self.coord_scale)
 
-        self.lc = LogoCode(self)
-        self.saved_pictures = []
-
-        self.block_operation = ''
-
         if self.interactive_mode:
             self._setup_misc()
             self._show_toolbar_palette(0, False)
@@ -264,13 +259,18 @@ class TurtleArtWindow():
                 PALETTES[PALETTE_NAMES.index('sensor')].append('voltage')
             self.audio_started = False
 
-        self.camera = False
+        self.camera_available = False
         v4l2src = gst.element_factory_make('v4l2src')
         if v4l2src.props.device_name is not None:
             PALETTES[PALETTE_NAMES.index('sensor')].append('readcamera')
             PALETTES[PALETTE_NAMES.index('sensor')].append('luminance')
             PALETTES[PALETTE_NAMES.index('sensor')].append('camera')
-            self.camera = True
+            self.camera_available = True
+
+        self.lc = LogoCode(self)
+        self.saved_pictures = []
+
+        self.block_operation = ''
 
         """
         The following code will initialize a USB RFID reader. Please note that
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