Factored out message generation form laser scan data and added javadoc

android_hokuyo/src/org/ros/android/hokuyo/LaserScanPublisher.java

@@ -68,32 +68,58 @@ public class LaserScanPublisher implements NodeMain {
     scipDevice.startScanning(new LaserScanListener() {
       @Override
       public void onNewLaserScan(LaserScan scan) {
-        org.ros.message.sensor_msgs.LaserScan message = 
-            node.getMessageFactory().newMessage("sensor_msgs/LaserScan");
-        // Some laser scanners have blind areas before and after the actual detection range.
-        // These are indicated by the front step and the last step configuration variables.
-        // Since the blind values never change, we can just ignore them when creating the 
-        // range array.
-        message.angle_increment = configuration.getAngleIncrement(); 
-        message.angle_min = configuration.getMinimumAngle();
-        message.angle_max = configuration.getMaximumAngle();
-        message.ranges = new float[configuration.getLastStep() - configuration.getFirstStep()];
-        for (int i = 0; i < message.ranges.length; i++) {
-          message.ranges[i] = (float) (scan.getRanges().get(i + configuration.getFirstStep()) / 1000.0);
-        }
-        message.time_increment = configuration.getTimeIncrement();
-        message.scan_time = configuration.getScanTime();
-        message.range_min = (float) (configuration.getMinimumMeasurment() / 1000.0);
-        message.range_max = (float) (configuration.getMaximumMeasurement() / 1000.0);
-        message.header.frame_id = laserFrame;
-        message.header.stamp = new org.ros.message.Time(scan.getTimeStamp()).add(timeOffset);
+        org.ros.message.sensor_msgs.LaserScan message = toLaserScanMessage(
+            laserFrame, configuration, scan);
         publisher.publish(message);
-      }
-    });
+      }});
   }
 
   @Override
   public void shutdown() {
     scipDevice.shutdown();
   }
+  
+
+  /**
+   * Construct a LaserScan message from sensor readings and the laser
+   * configuration.
+   * 
+   * Also gets rid of readings that don't contain any information.
+   * 
+   * Some laser scanners have blind areas before and after the actual detection
+   * range. These are indicated by the frontStep and the lastStep properties of
+   * the laser's configuration. Since the blind values never change, we can just
+   * ignore them when copying the range readings.
+   * 
+   * @param laserFrame
+   *          The laser's sensor frame.
+   * @param configuration
+   *          The laser's current configuration.
+   * @param scan
+   *          The actual range readings.
+   * @return A new LaserScan message
+   */
+  private org.ros.message.sensor_msgs.LaserScan toLaserScanMessage(
+      String laserFrame, Configuration configuration, LaserScan scan) {
+    org.ros.message.sensor_msgs.LaserScan message = node.getMessageFactory()
+        .newMessage("sensor_msgs/LaserScan");
+    message.angle_increment = configuration.getAngleIncrement();
+    message.angle_min = configuration.getMinimumAngle();
+    message.angle_max = configuration.getMaximumAngle();
+    message.ranges = new float[configuration.getLastStep()
+        - configuration.getFirstStep()];
+    for (int i = 0; i < message.ranges.length; i++) {
+      message.ranges[i] = (float) (scan.getRanges().get(
+          i + configuration.getFirstStep()) / 1000.0);
+    }
+    message.time_increment = configuration.getTimeIncrement();
+    message.scan_time = configuration.getScanTime();
+    message.range_min = (float) (configuration.getMinimumMeasurment() / 1000.0);
+    message.range_max = (float) (configuration.getMaximumMeasurement() / 1000.0);
+    message.header.frame_id = laserFrame;
+    message.header.stamp = new org.ros.message.Time(scan.getTimeStamp())
+        .add(timeOffset);
+    return message;
+  }
+
 }