gecko-dev/image/test/unit/image_load_helpers.js

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JavaScript

/*
* Helper structures to track callbacks from image and channel loads.
*/
// One bit per callback that imageListener below implements. Stored in
// ImageListener.state.
// START_REQUEST and STOP_REQUEST are also reused by ChannelListener, and
// stored in ChannelListener.requestStatus.
const START_REQUEST = 0x01;
const START_DECODE = 0x02;
const START_CONTAINER = 0x04;
const START_FRAME = 0x08;
const STOP_FRAME = 0x10;
const STOP_CONTAINER = 0x20;
const STOP_DECODE = 0x40;
const STOP_REQUEST = 0x80;
const ALL_BITS = 0xFF;
// An implementation of imgIDecoderObserver with the ability to call specified
// functions on onStartRequest and onStopRequest.
function ImageListener(start_callback, stop_callback)
{
this.onStartRequest = function onStartRequest(aRequest)
{
do_check_false(this.synchronous);
this.state |= START_REQUEST;
if (this.start_callback)
this.start_callback(this, aRequest);
}
this.onStartDecode = function onStartDecode(aRequest)
{
do_check_false(this.synchronous);
this.state |= START_DECODE;
}
this.onStartContainer = function onStartContainer(aRequest, aContainer)
{
do_check_false(this.synchronous);
this.state |= START_CONTAINER;
}
this.onStartFrame = function onStartFrame(aRequest, aFrame)
{
do_check_false(this.synchronous);
this.state |= START_FRAME;
}
this.onStopFrame = function onStopFrame(aRequest, aFrame)
{
do_check_false(this.synchronous);
this.state |= STOP_FRAME;
}
this.onStopContainer = function onStopContainer(aRequest, aContainer)
{
do_check_false(this.synchronous);
this.state |= STOP_CONTAINER;
}
this.onStopDecode = function onStopDecode(aRequest, status, statusArg)
{
do_check_false(this.synchronous);
this.state |= STOP_DECODE;
}
this.onStopRequest = function onStopRequest(aRequest, aIsLastPart)
{
do_check_false(this.synchronous);
// onStopDecode must always be called before, and with, onStopRequest. See
// imgRequest::OnStopDecode for more information.
do_check_true(!!(this.state & STOP_DECODE));
// We have to cancel the request when we're done with it to break any
// reference loops!
aRequest.cancel(0);
this.state |= STOP_REQUEST;
if (this.stop_callback)
this.stop_callback(this, aRequest);
}
// 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.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;
}