michael@0: /*
michael@0:  * Helper structures to track callbacks from image and channel loads.
michael@0:  */
michael@0: 
michael@0: // START_REQUEST and STOP_REQUEST are used by ChannelListener, and
michael@0: // stored in ChannelListener.requestStatus.
michael@0: const START_REQUEST = 0x01;
michael@0: const STOP_REQUEST = 0x02;
michael@0: const DATA_AVAILABLE = 0x04;
michael@0: 
michael@0: // One bit per callback that imageListener below implements. Stored in
michael@0: // ImageListener.state.
michael@0: const SIZE_AVAILABLE = 0x01;
michael@0: const FRAME_UPDATE = 0x02;
michael@0: const FRAME_COMPLETE = 0x04;
michael@0: const LOAD_COMPLETE = 0x08;
michael@0: const DECODE_COMPLETE = 0x10;
michael@0: 
michael@0: // An implementation of imgIScriptedNotificationObserver with the ability to
michael@0: // call specified functions on onStartRequest and onStopRequest.
michael@0: function ImageListener(start_callback, stop_callback)
michael@0: {
michael@0:   this.sizeAvailable = function onSizeAvailable(aRequest)
michael@0:   {
michael@0:     do_check_false(this.synchronous);
michael@0: 
michael@0:     this.state |= SIZE_AVAILABLE;
michael@0: 
michael@0:     if (this.start_callback)
michael@0:       this.start_callback(this, aRequest);
michael@0:   }
michael@0:   this.frameComplete = function onFrameComplete(aRequest)
michael@0:   {
michael@0:     do_check_false(this.synchronous);
michael@0: 
michael@0:     this.state |= FRAME_COMPLETE;
michael@0:   }
michael@0:   this.decodeComplete = function onDecodeComplete(aRequest)
michael@0:   {
michael@0:     do_check_false(this.synchronous);
michael@0: 
michael@0:     this.state |= DECODE_COMPLETE;
michael@0:   }
michael@0:   this.loadComplete = function onLoadcomplete(aRequest)
michael@0:   {
michael@0:     do_check_false(this.synchronous);
michael@0: 
michael@0:     try {
michael@0:       aRequest.requestDecode();
michael@0:     } catch (e) {
michael@0:       do_print("requestDecode threw " + e);
michael@0:     }
michael@0: 
michael@0:     this.state |= LOAD_COMPLETE;
michael@0: 
michael@0:     if (this.stop_callback)
michael@0:       this.stop_callback(this, aRequest);
michael@0:   }
michael@0:   this.frameUpdate = function onFrameUpdate(aRequest)
michael@0:   {
michael@0:   }
michael@0:   this.isAnimated = function onIsAnimated()
michael@0:   {
michael@0:   }
michael@0: 
michael@0:   // Initialize the synchronous flag to true to start. This must be set to
michael@0:   // false before exiting to the event loop!
michael@0:   this.synchronous = true;
michael@0: 
michael@0:   // A function to call when onStartRequest is called.
michael@0:   this.start_callback = start_callback;
michael@0: 
michael@0:   // A function to call when onStopRequest is called.
michael@0:   this.stop_callback = stop_callback;
michael@0: 
michael@0:   // The image load/decode state.
michael@0:   // A bitfield that tracks which callbacks have been called. Takes the bits
michael@0:   // defined above.
michael@0:   this.state = 0;
michael@0: }
michael@0: 
michael@0: function NS_FAILED(val)
michael@0: {
michael@0:   return !!(val & 0x80000000);
michael@0: }
michael@0: 
michael@0: function ChannelListener()
michael@0: {
michael@0:   this.onStartRequest = function onStartRequest(aRequest, aContext)
michael@0:   {
michael@0:     if (this.outputListener)
michael@0:       this.outputListener.onStartRequest(aRequest, aContext);
michael@0: 
michael@0:     this.requestStatus |= START_REQUEST;
michael@0:   }
michael@0: 
michael@0:   this.onDataAvailable = function onDataAvailable(aRequest, aContext, aInputStream, aOffset, aCount)
michael@0:   {
michael@0:     if (this.outputListener)
michael@0:       this.outputListener.onDataAvailable(aRequest, aContext, aInputStream, aOffset, aCount);
michael@0: 
michael@0:     this.requestStatus |= DATA_AVAILABLE;
michael@0:   }
michael@0: 
michael@0:   this.onStopRequest = function onStopRequest(aRequest, aContext, aStatusCode)
michael@0:   {
michael@0:     if (this.outputListener)
michael@0:       this.outputListener.onStopRequest(aRequest, aContext, aStatusCode);
michael@0: 
michael@0:     // If we failed (or were canceled - failure is implied if canceled),
michael@0:     // there's no use tracking our state, since it's meaningless.
michael@0:     if (NS_FAILED(aStatusCode))
michael@0:       this.requestStatus = 0;
michael@0:     else
michael@0:       this.requestStatus |= STOP_REQUEST;
michael@0:   }
michael@0: 
michael@0:   // A listener to pass the notifications we get to.
michael@0:   this.outputListener = null;
michael@0: 
michael@0:   // The request's status. A bitfield that holds one or both of START_REQUEST
michael@0:   // and STOP_REQUEST, according to which callbacks have been called on the
michael@0:   // associated request.
michael@0:   this.requestStatus = 0;
michael@0: }