<?xml version="1.0"?>
<!DOCTYPE gsdoc PUBLIC "-//GNUstep//DTD gsdoc 1.0.4//EN" "http://www.gnustep.org/gsdoc-1_0_4.dtd">
<gsdoc base="GSTicker">
  <head>
    <title>GSTicker class documentation</title>
    <author name="Richard Frith-Macdonald">
      <email address="rfm@gnu.org">
        rfm@gnu.org
      </email>
    </author>
    <version>33243</version>
    <date>2011-06-04 15:50:40 +0100 (Sat, 04 Jun 2011)</date>
    <copy>2005 Free Software Foundation, Inc.</copy>
  </head>
  <body>
    <front><contents /></front>
    <chapter>
      <heading>
        Software documentation for the GSTicker class
      </heading>
      <class name="GSTicker" super="NSObject">
        <declared>GSTicker.h</declared>
        <conform>GSTicker</conform>
        <desc>
          Wrapper round the more efficient ticker functions...
          this class provides convenience methods to get NSDate
          objects, and also provides support for registering
          observers ofr second by second ticks.
        </desc>
        <method type="NSDate*" factory="yes">
          <sel>last</sel>
          <desc>
            Calls
            <ref type="function" id="GSTickerTimeLast">
              GSTickerTimeLast()
            </ref>
            and returns the result as an NSDate.
          </desc>
        </method>
        <method type="void" factory="yes">
          <sel>newSecond:</sel>
          <arg type="id">userInfo</arg>
          <desc>
            A dummy method... does nothing, but allows the GSTicker
            class itsself to act as an observer of regular
            timeouts. <br /> Thus, you may register the class
            as its own observer in order to set up a timer to ensure
            that date/time information is updated at the start of
            every second.
          </desc>
        </method>
        <method type="NSDate*" factory="yes">
          <sel>now</sel>
          <desc>
            Calls
            <ref type="function" id="GSTickerTimeNow">
              GSTickerTimeNow()
            </ref>
            and returns the result as an NSDate.
          </desc>
        </method>
        <method type="void" factory="yes">
          <sel>registerObserver:</sel>
          <arg type="id&lt;GSTicker&gt;">anObject</arg>
          <sel>userInfo:</sel>
          <arg type="id">userInfo</arg>
          <desc>
            Registers an object to receive a
            <ref type="method" id="-newSecond:" class="(GSTicker)">
              [&lt;GSTicker&gt;-newSecond:]
            </ref>
            message at the start of every second. <br /> Also
            starts a timer in the current thread (unless one is
            already running) to notify registered objects of
            new seconds. <br /> The observer and the
            <var>userInfo</var> are retained by the ticker.
            <br /> Adding an observer more than once has no
            effect. <br /> NB. You must not add or remove
            observers inside the callback routine.
          </desc>
        </method>
        <method type="NSDate*" factory="yes">
          <sel>start</sel>
          <desc>
            Returns the result of
            <ref type="function" id="GSTickerTimeStart">
              GSTickerTimeStart()
            </ref>
            as an NSDate.
          </desc>
        </method>
        <method type="unsigned" factory="yes">
          <sel>tick</sel>
          <desc>
            Calls
            <ref type="function" id="GSTickerTimeTick">
              GSTickerTimeTick()
            </ref>
            and returns the result.
          </desc>
        </method>
        <method type="void" factory="yes">
          <sel>unregisterObserver:</sel>
          <arg type="id&lt;GSTicker&gt;">anObject</arg>
          <desc>
            Unregisters an observer previously set in the
            current thread using the
            <ref type="method" id="+registerObserver:userInfo:">
              +registerObserver:userInfo:
            </ref>
            method. <br /> If all observers in a thread are
            removed, the timer for the thread is cancelled at
            the start of the next second.
          </desc>
        </method>
        <method type="void" factory="yes">
          <sel>update</sel>
          <desc>
            Calls
            <ref type="function" id="GSTickerTimeNow">
              GSTickerTimeNow()
            </ref>
            ;
          </desc>
        </method>
        <method type="NSDate*">
          <sel>last</sel>
          <desc>
            Calls
            <ref type="function" id="GSTickerTimeLast">
              GSTickerTimeLast()
            </ref>
            and returns the result as an NSDate.
          </desc>
        </method>
        <method type="void">
          <sel>newSecond:</sel>
          <arg type="id">userInfo</arg>
          <desc>
            See
            <ref type="method" id="+newSecond:">
              +newSecond:
            </ref>
          </desc>
        </method>
        <method type="NSDate*">
          <sel>now</sel>
          <desc>
            Calls
            <ref type="function" id="GSTickerTimeNow">
              GSTickerTimeNow()
            </ref>
            and returns the result as an NSDate.
          </desc>
        </method>
        <method type="NSDate*">
          <sel>start</sel>
          <desc>
            Returns the result of
            <ref type="function" id="GSTickerTimeStart">
              GSTickerTimeStart()
            </ref>
            as an NSDate.
          </desc>
        </method>
        <method type="unsigned">
          <sel>tick</sel>
          <desc>
            Calls
            <ref type="function" id="GSTickerTimeTick">
              GSTickerTimeTick()
            </ref>
            and returns the result.
          </desc>
        </method>
        <method type="void">
          <sel>update</sel>
          <desc>
            Calls
            <ref type="function" id="GSTickerTimeNow">
              GSTickerTimeNow()
            </ref>
            ;
          </desc>
        </method>
      </class>
    </chapter>
    <chapter>
      <heading>
        Software documentation for the GSTicker protocol
      </heading>
      <protocol name="GSTicker">
        <declared>GSTicker.h</declared>
        <conform>NSObject</conform>
        <desc>
          <em>Description forthcoming.</em>
        </desc>
        <method type="void">
          <sel>newSecond:</sel>
          <arg type="id">userInfo</arg>
          <desc>
            Sent to tell observers that the ticker has noticed
            that a new second has occurred. The tick argument is
            the user information provided in when registering the
            observer. <br /> This message is sent to each
            registered observer when the timeout for the
            thread occurs. It is not guaranteed to be called
            every second... other processing in the thread may
            delay it.
          </desc>
        </method>
      </protocol>
    </chapter>
    <chapter>
      <heading>GSTicker functions</heading>
      <p></p>
      <function type="NSTimeInterval" name="GSTickerTimeLast">
        <desc>
          Returns the timestamp of the most recent call to
          <ref type="function" id="GSTickerTimeNow">
            GSTickerTimeNow()
          </ref>
          .
        </desc>
      </function>
      <function type="NSTimeInterval" name="GSTickerTimeNow">
        <desc>
          Convenience function to provide timing
          information quickly. <br /> This returns the
          current date/time, and stores the value for use by
          the
          <ref type="function" id="GSTickerTimeLast">
            GSTickerTimeLast()
          </ref>
          function.
        </desc>
      </function>
      <function type="NSTimeInterval" name="GSTickerTimeStart">
        <desc>
          This returns the timestamp from which GSTicker was first
          used.
        </desc>
      </function>
      <function type="unsigned int" name="GSTickerTimeTick">
        <desc>
          A convenience method to return the current clock 'tick'...
          which is the current second based on the time we
          started. This does <em>not</em> check the current
          time, but relies on
          <ref type="function" id="GSTickerTimeLast">
            GSTickerTimeLast()
          </ref>
          returning an up to date value (so if you need an
          accurate tick, you should ensure that
          <ref type="function" id="GSTickerTimeNow">
            GSTickerTimeNow()
          </ref>
          is called at least once a second). <br /> The returned
          value is always greater than zero, and is basically
          calculated as (GSTickerTimeLast() -
          <ref type="function" id="GSTickerTimeStart">
            GSTickerTimeStart()
          </ref>
          + 1). <br /> In the event that the system clock is reset
          into the past, the value of
          <ref type="function" id="GSTickerTimeStart">
            GSTickerTimeStart()
          </ref>
          is automatically adjusted to ensure that the result of a
          call to
          <ref type="function" id="GSTickerTimeTick">
            GSTickerTimeTick()
          </ref>
          is never less than the result of any earlier call to the
          function.
        </desc>
      </function>
    </chapter>
  </body>
</gsdoc>
