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 /*

  * Helper structures to track callbacks from image and channel loads.

  */

 // START_REQUEST and STOP_REQUEST are used by ChannelListener, and

 // stored in ChannelListener.requestStatus.

 const START_REQUEST = 0x01;

 const STOP_REQUEST = 0x02;

 const DATA_AVAILABLE = 0x04;

 // One bit per callback that imageListener below implements. Stored in

 // ImageListener.state.

 const SIZE_AVAILABLE = 0x01;

 const FRAME_UPDATE = 0x02;

 const FRAME_COMPLETE = 0x04;

 const LOAD_COMPLETE = 0x08;

 const DECODE_COMPLETE = 0x10;

 // An implementation of imgIScriptedNotificationObserver with the ability to

 // call specified functions on onStartRequest and onStopRequest.

 function ImageListener(start_callback, stop_callback)

 {

   this.sizeAvailable = function onSizeAvailable(aRequest)

   {

     do_check_false(this.synchronous);

     this.state |= SIZE_AVAILABLE;

     if (this.start_callback)

       this.start_callback(this, aRequest);

   }

   this.frameComplete = function onFrameComplete(aRequest)

   {

     do_check_false(this.synchronous);

     this.state |= FRAME_COMPLETE;

   }

   this.decodeComplete = function onDecodeComplete(aRequest)

   {

     do_check_false(this.synchronous);

     this.state |= DECODE_COMPLETE;

   }

   this.loadComplete = function onLoadcomplete(aRequest)

   {

     do_check_false(this.synchronous);

     try {

       aRequest.requestDecode();

     } catch (e) {

       do_print("requestDecode threw " + e);

     }

     this.state |= LOAD_COMPLETE;

     if (this.stop_callback)

       this.stop_callback(this, aRequest);

   }

   this.frameUpdate = function onFrameUpdate(aRequest)

   {

   }

   this.isAnimated = function onIsAnimated()

   {

   }

   // Initialize the synchronous flag to true to start. This must be set to

   // false before exiting to the event loop!

   this.synchronous = true;

   // A function to call when onStartRequest is called.

   this.start_callback = start_callback;

   // A function to call when onStopRequest is called.

   this.stop_callback = stop_callback;

   // The image load/decode state.

   // A bitfield that tracks which callbacks have been called. Takes the bits

   // defined above.

   this.state = 0;

 }

 function NS_FAILED(val)

 {

   return !!(val & 0x80000000);

 }

 function ChannelListener()

 {

   this.onStartRequest = function onStartRequest(aRequest, aContext)

   {

     if (this.outputListener)

       this.outputListener.onStartRequest(aRequest, aContext);

     this.requestStatus |= START_REQUEST;

   }

   this.onDataAvailable = function onDataAvailable(aRequest, aContext, aInputStream, aOffset, aCount)

   {

     if (this.outputListener)

       this.outputListener.onDataAvailable(aRequest, aContext, aInputStream, aOffset, aCount);

     this.requestStatus |= DATA_AVAILABLE;

   }

   this.onStopRequest = function onStopRequest(aRequest, aContext, aStatusCode)

   {

     if (this.outputListener)

       this.outputListener.onStopRequest(aRequest, aContext, aStatusCode);

     // If we failed (or were canceled - failure is implied if canceled),

     // there's no use tracking our state, since it's meaningless.

     if (NS_FAILED(aStatusCode))

       this.requestStatus = 0;

     else

       this.requestStatus |= STOP_REQUEST;

   }

   // A listener to pass the notifications we get to.

   this.outputListener = null;

   // The request's status. A bitfield that holds one or both of START_REQUEST

   // and STOP_REQUEST, according to which callbacks have been called on the

   // associated request.

   this.requestStatus = 0;

 }