[skycastle-commits] SF.net SVN: skycastle: [217] trunk/skycastle/modules/utils/src/main/java/ org/skycastle/util/fpscounter/FpsCounter.java
- From: zzorn@xxxxxxxxxxxxxxxxxxxxx
- To: skycastle-commits@xxxxxxxxxxxxx
- Date: Thu, 04 Oct 2007 16:27:33 -0700
Revision: 217
http://skycastle.svn.sourceforge.net/skycastle/?rev=217&view=rev
Author: zzorn
Date: 2007-10-04 16:27:33 -0700 (Thu, 04 Oct 2007)
Log Message:
-----------
Some improvements to the FPS counter code
Modified Paths:
--------------
trunk/skycastle/modules/utils/src/main/java/org/skycastle/util/fpscounter/FpsCounter.java
Modified:
trunk/skycastle/modules/utils/src/main/java/org/skycastle/util/fpscounter/FpsCounter.java
===================================================================
---
trunk/skycastle/modules/utils/src/main/java/org/skycastle/util/fpscounter/FpsCounter.java
2007-10-04 23:26:45 UTC (rev 216)
+++
trunk/skycastle/modules/utils/src/main/java/org/skycastle/util/fpscounter/FpsCounter.java
2007-10-04 23:27:33 UTC (rev 217)
@@ -1,35 +1,27 @@
-/**
- * Copyright Hans H\xE4ggstr\xF6m 2004
- * hans.haggstrom at iki dot fi
- */
-
package org.skycastle.util.fpscounter;
/**
- * A class used to count frames per second.
+ * An utlity class for counting number of frames per second.
* <p/>
* Usage: Create an instance, then every frame call onFrame().
* The frames per second value can be read at any time using getFps().
* <p/>
- * IDEA: The implementation could use a longer time sampling span than a
single frame to get
- * around the imprecision of the standard Java timer.
- * <p/>
- * IDEA: Smoothness feature, averaging the FPS value a bit with the previous
value - this produces smoother changes,
- * IDEA which is better looking for some kinds of FPS gauges.
- * <p/>
- * IDEA: Make NUMBER_OF_FPS_SAMPLE_FRAMES a caller adjustable property?
+ * Thread safe, as long as onFrame is only called from a single thread.
*
* @author Hans H\xE4ggstr\xF6m
*/
-public class FpsCounter
+public final class FpsCounter
{
//======================================================================
// Private Fields
- private double myFramesPerSecond = 0;
+ private final Object mySyncLock = new Object();
+
+ // IDEA: Also calculate average over a number of frames, if a smoother
value is needed, or if trend information is needed.
+ private double myFramesPerSecond = -1;
+ private double mySecondsBetweenFrames = -1;
private long myFrameStartTime_ns = -1;
- private double mySecondsSinceLastFrame = 0;
private boolean myHasPreviousSample = false;
//======================================================================
@@ -45,7 +37,7 @@
/**
* Creates a new FpsCounter.
- * Initially the frames per second property will be 0, until onFrame() is
called.
+ * Initially the frames per second property will be a negative value,
until onFrame() is called (twice).
*/
public FpsCounter()
{
@@ -55,68 +47,85 @@
// Other Public Methods
/**
- * @return the number of frames rendered per second, or 0 if the counter
has not yet been started or has been stopped.
+ * @return the number of frames rendered per second, or a negative value
if the counter has not yet been started or has been stopped.
*/
public double getFramesPerSecond()
{
- return myFramesPerSecond;
+ synchronized ( mySyncLock )
+ {
+ return myFramesPerSecond;
+ }
}
/**
- * @return number of seconds since the last frame, or a negative value if
there were no earlier frames.
+ * @return number of seconds between the most recent frame and the frame
before that,
+ * or a negative value if there were no earlier frames.
* Uses the averaged frames per second instead of the latest
measurement.
*/
- public double getSecondsSinceLastFrame()
+ public double getSecondsBetweenFrames()
{
- return mySecondsSinceLastFrame;
+ synchronized ( mySyncLock )
+ {
+ return mySecondsBetweenFrames;
+ }
}
/**
* Call this method once each frame, to allow the counter to compute the
frames per second property.
+ * <p/>
+ * NOTE: Should be called from a single thread, or wrapped in a
syncronized object. If called from two different
+ * threads, there could be frames with negative fps or
secondsBetweenFrames.
*/
public void onFrame()
{
// Get start time of current frame
- long now_ns = System.nanoTime();
+ final long now_ns = System.nanoTime();
- // Only update the fps property if we have two values already, so the
duration is valid.
- if ( myHasPreviousSample )
+ synchronized ( mySyncLock )
{
- // Calculate the duration since the last frame
- long duration_ns = now_ns - myFrameStartTime_ns;
+ // Only update the fps property if we have two values already, so
the duration is valid.
+ if ( myHasPreviousSample )
+ {
+ // Calculate the duration since the last frame
+ long duration_ns = now_ns - myFrameStartTime_ns;
- // Avoid division by zero if the frame rate is very high
- if ( duration_ns == 0 )
+ // Avoid division by zero if the frame rate is very high
+ if ( duration_ns == 0 )
+ {
+ duration_ns = 1;
+ }
+
+ // Update the frames per second and time since last frame
property
+ mySecondsBetweenFrames = ( 1.0 * duration_ns ) /
TICKS_PER_SECOND;
+ myFramesPerSecond = TICKS_PER_SECOND / duration_ns;
+ }
+ else
{
- duration_ns = 1;
+ // Now we have one sample already, so next time we can update
the property
+ myHasPreviousSample = true;
}
- // Update the frames per second and time since last frame property
- mySecondsSinceLastFrame = ( 1.0 * duration_ns ) / TICKS_PER_SECOND;
- myFramesPerSecond = TICKS_PER_SECOND / duration_ns;
+ // Remember current frame start time
+ myFrameStartTime_ns = now_ns;
}
- else
- {
- // Now we have one sample already, so next time we can update the
property
- myHasPreviousSample = true;
- }
-
- // Remember current frame start time
- myFrameStartTime_ns = now_ns;
}
/**
- * Sets the frames per second value to 0, until onFrame() is called again.
+ * Sets the frames per second and seconds since last frame value to
negative values, until onFrame() is called again.
*/
public void stopCounting()
{
- myFramesPerSecond = 0;
- myHasPreviousSample = false;
+ synchronized ( mySyncLock )
+ {
+ myFramesPerSecond = -1;
+ mySecondsBetweenFrames = -1;
+ myHasPreviousSample = false;
+ }
}
-
}
+
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