[jsk_perception/node_scripts/tile_image.py] process and publish only when subscriber exists

Author: k-okada

jsk_perception/node_scripts/tile_image.py

@@ -130,18 +130,24 @@ def _append_images(self, imgs):
                 out_bgr = jsk_recognition_utils.get_tile_image(
                     imgs, tile_shape=shape_xy)
                 self.cache_img = out_bgr
-        bridge = cv_bridge.CvBridge()
-        imgmsg = bridge.cv2_to_imgmsg(out_bgr, encoding='bgr8')
-        self.pub_img.publish(imgmsg)
-
-        compressed_msg = CompressedImage()
-        compressed_msg.header = imgmsg.header
-        compressed_msg.format = imgmsg.encoding + '; jpeg compressed bgr8'
-        compressed_msg.data = np.array(
-            cv2.imencode('.jpg', out_bgr)[1]).tostring()
-        self.pub_compressed_img.publish(compressed_msg)
+        if self.pub_img.get_num_connections() > 0:
+            bridge = cv_bridge.CvBridge()
+            imgmsg = bridge.cv2_to_imgmsg(out_bgr, encoding='bgr8')
+            self.pub_img.publish(imgmsg)
+
+        if self.pub_compressed_img.get_num_connections() > 0:
+            compressed_msg = CompressedImage()
+            compressed_msg.header = imgmsg.header
+            compressed_msg.format = imgmsg.encoding + '; jpeg compressed bgr8'
+            compressed_msg.data = np.array(
+                cv2.imencode('.jpg', out_bgr)[1]).tostring()
+            self.pub_compressed_img.publish(compressed_msg)
 
     def _apply(self, *msgs):
+        if self.pub_img.get_num_connections() == 0 and
+           self.pub_compressed_img.get_num_connections() == 0:
+            return
+
         bridge = cv_bridge.CvBridge()
         imgs = []
         for msg, topic in zip(msgs, self.input_topics):