An observer for page loads in a custom xul:browser - firefox-addon

Question

In my firefox extension I'm creating a xul:browser element. I want to have an observer that intercepts any url changes within the embedded browser and opens the url in a new browser tab (in the main browser). I'd also like new windows spawned by the xul:browser window to open in a tab instead of a new browser window.
I've created an observer which works, but I don't yet know how to apply that observer only to the xul:browser element.
function myFunction(){
var container = jQuery("#container")[0];
var new_browser_element = document.createElement('browser');
container.appendChild(new_browser_element);
var observerService = Components.classes["#mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
observerService.addObserver(myObserver, "http-on-modify-request", false);
}
var myObserver = {
observe: function(aSubject, aTopic, aData){
if (aTopic != 'http-on-modify-request'){
aSubject.QueryInterface(Components.interfaces.nsIHttpChannel);
// alert(aSubject.URI.spec);
// Now open url in new tab
}
},
QueryInterface: function(iid){
if (!iid.equals(Components.interfaces.nsISupports) &&
!iid.equals(Components.interfaces.nsIObserver))
throw Components.results.NS_ERROR_NO_INTERFACE;
return this;
}
};

Answer 1

You could try:
var myObserver = {
observe: function(aSubject, aTopic, aData){
if (aTopic == 'http-on-modify-request')
{
aSubject.QueryInterface(Components.interfaces.nsIHttpChannel);
var url = aSubject.URI.spec;
var postData ;
if (aSubject.requestMethod.toLowerCase() == "post")
{
var postText = this.readPostTextFromRequest(request);
if (postText)
{
var dataString = parseQuery(postText);
postData = postDataFromString(dataString);
}
}
var oHttp = aSubject.QueryInterface(Components.interfaces.nsIHttpChannel);
var interfaceRequestor = oHttp.notificationCallbacks.QueryInterface(Components.interfaces.nsIInterfaceRequestor);
var DOMWindow = interfaceRequestor.getInterface(Components.interfaces.nsIDOMWindow);
//check if it is one of your mini browser windows
if (jQuery(DOMWindow).hasClass('mini_browser'))
{
openInTab(url, postData);
var request = aSubject.QueryInterface(Components.interfaces.nsIRequest);
request.cancel(Components.results.NS_BINDING_ABORTED);
}
}
},
QueryInterface: function(iid){
if (!iid.equals(Components.interfaces.nsISupports) &&
!iid.equals(Components.interfaces.nsIObserver))
throw Components.results.NS_ERROR_NO_INTERFACE;
return this;
},
readPostTextFromRequest : function(request) {
var is = request.QueryInterface(Components.interfaces.nsIUploadChannel).uploadStream;
if (is)
{
var ss = is.QueryInterface(Components.interfaces.nsISeekableStream);
var prevOffset;
if (ss)
{
prevOffset = ss.tell();
ss.seek(Components.interfaces.nsISeekableStream.NS_SEEK_SET, 0);
}
// Read data from the stream..
var charset = "UTF-8";
var text = this.readFromStream(is, charset, true);
// Seek locks the file so, seek to the beginning only if necko hasn't read it yet,
// since necko doesn't seek to 0 before reading (at lest not till 459384 is fixed).
if (ss && prevOffset == 0)
ss.seek(Components.interfaces.nsISeekableStream.NS_SEEK_SET, 0);
return text;
}
else {
dump("Failed to Query Interface for upload stream.\n");
}
}
return null;
},
readFromStream : function(stream, charset, noClose)
{
var sis = Components.classes["#mozilla.org/binaryinputstream;1"]
.getService(Components.interfaces.nsIBinaryInputStream);
sis.setInputStream(stream);
var segments = [];
for (var count = stream.available(); count; count = stream.available())
segments.push(sis.readBytes(count));
if (!noClose)
sis.close();
var text = segments.join("");
return text;
}
};
function openInTab(url, postData)
{
var wm = Components.classes["#mozilla.org/appshell/window-mediator;1"]
.getService(Components.interfaces.nsIWindowMediator);
var recentWindow = wm.getMostRecentWindow("navigator:browser");
if (recentWindow)
{
// Use an existing browser window, open tab and "select" it
recentWindow.gBrowser.selectedTab = recentWindow.gBrowser.addTab(url, null, null, postData);
}
}
function parseQuery() {
var qry = this;
var rex = /[?&]?([^=]+)(?:=([^&#]*))?/g;
var qmatch, key;
var paramValues = {};
// parse querystring storing key/values in the ParamValues associative array
while (qmatch = rex.exec(qry)) {
key = decodeURIComponent(qmatch[1]);// get decoded key
val = decodeURIComponent(qmatch[2]);// get decoded value
paramValues[key] = val;
}
return paramValues;
}
function postDataFromString(dataString)
{
// POST method requests must wrap the encoded text in a MIME
// stream
var stringStream = Components.classes["#mozilla.org/io/string-input-stream;1"]
.createInstance(Components.interfaces.nsIStringInputStream);
if ("data" in stringStream) // Gecko 1.9 or newer
stringStream.data = dataString;
else // 1.8 or older
stringStream.setData(dataString, dataString.length);
var postData = Components.classes["#mozilla.org/network/mime-input-stream;1"].
createInstance(Components.interfaces.nsIMIMEInputStream);
postData.addHeader("Content-Type", "application/x-www-form-urlencoded");
postData.addContentLength = true;
postData.setData(stringStream);
return postData;
}
I'll update this to fill in the blanks in a bit.
edit: see http://forums.mozillazine.org/viewtopic.php?p=2772951#p2772951 for how to get the source window of a request.
Request cancellation code from http://zenit.senecac.on.ca/wiki/index.php/Support_For_OpenID.
see http://mxr.mozilla.org/mozilla-central/source/netwerk/base/public/nsIRequest.idl for details on nsIRequest.
See http://forums.mozillazine.org/viewtopic.php?p=2404533#p2404533 and https://developer.mozilla.org/en/XUL/Method/addTab for the definition of addTab.
parseQuery comes from http://blog.strictly-software.com/2008/10/using-javascript-to-parse-querystring.html.
See https://developer.mozilla.org/en/Code_snippets/Post_data_to_window#Preprocessing_POST_data for how to process post data in a form suitable for addTab.
ReadPostFromText and ReadTextFromStream both come from firebug (though slightly modified)