Bug 808231 - Implement add/removeNextPaintListener() methods for mozbrowsers r=jlebar a=blocking-basecamp

dom/browser-element/BrowserElementChild.js

@@ -58,6 +58,8 @@ function BrowserElementChild() {
   this._forcedVisible = true;
   this._ownerVisible = true;
 
+  this._nextPaintHandler = null;
+
   this._init();
 };
 
@@ -109,11 +111,10 @@ BrowserElementChild.prototype = {
                      /* useCapture = */ true,
                      /* wantsUntrusted = */ false);
 
-    this._afterPaintHandlerClosure = this._afterPaintHandler.bind(this);
-    addEventListener('MozAfterPaint',
-                     this._afterPaintHandlerClosure,
-                     /* useCapture = */ true,
-                     /* wantsUntrusted = */ false);
+    // Registers a MozAfterPaint handler for the very first paint.
+    this._addMozAfterPaintHandler(function () {
+      sendAsyncMsg('firstpaint');
+    });
 
     var self = this;
     function addMsgListener(msg, handler) {
@@ -135,6 +136,8 @@ BrowserElementChild.prototype = {
     addMsgListener("fire-ctx-callback", this._recvFireCtxCallback);
     addMsgListener("owner-visibility-change", this._recvOwnerVisibilityChange);
     addMsgListener("exit-fullscreen", this._recvExitFullscreen.bind(this));
+    addMsgListener("activate-next-paint-listener", this._activateNextPaintListener.bind(this));
+    addMsgListener("deactivate-next-paint-listener", this._deactivateNextPaintListener.bind(this));
 
     let els = Cc["@mozilla.org/eventlistenerservice;1"]
                 .getService(Ci.nsIEventListenerService);
@@ -361,16 +364,39 @@ BrowserElementChild.prototype = {
     }
   },
 
-  _afterPaintHandler: function(e) {
-    let uri = docShell.QueryInterface(Ci.nsIWebNavigation).currentURI;
-    debug("Got afterpaint event: " + uri.spec);
-    if (uri.spec != "about:blank") {
-      /* this._afterPaintHandlerClosure == arguments.callee, except we're in
-       * strict mode so we don't have arguments.callee. */
-      removeEventListener('MozAfterPaint', this._afterPaintHandlerClosure,
-                          /* useCapture */ true);
+  _addMozAfterPaintHandler: function(callback) {
+    function onMozAfterPaint() {
+      let uri = docShell.QueryInterface(Ci.nsIWebNavigation).currentURI;
+      debug("Got afterpaint event: " + uri.spec);
+      if (uri.spec != "about:blank") {
+        removeEventListener('MozAfterPaint', onMozAfterPaint,
+                            /* useCapture = */ true);
+        callback();
+      }
+    }
 
-      sendAsyncMsg('firstpaint');
+    addEventListener('MozAfterPaint', onMozAfterPaint, /* useCapture = */ true);
+    return onMozAfterPaint;
+  },
+
+  _removeMozAfterPaintHandler: function(listener) {
+    removeEventListener('MozAfterPaint', listener,
+                        /* useCapture = */ true);
+  },
+
+  _activateNextPaintListener: function(e) {
+    if (!this._nextPaintHandler) {
+      this._nextPaintHandler = this._addMozAfterPaintHandler(function () {
+        this._nextPaintHandler = null;
+        sendAsyncMsg('nextpaint');
+      }.bind(this));
+    }
+  },
+
+  _deactivateNextPaintListener: function(e) {
+    if (this._nextPaintHandler) {
+      this._removeMozAfterPaintHandler(this._nextPaintHandler);
+      this._nextPaintHandler = null;
     }
   },
 

dom/browser-element/BrowserElementParent.js

@@ -176,6 +176,7 @@ function BrowserElementParent(frameLoader, hasRemoteFrame) {
   this._domRequestCounter = 0;
   this._pendingDOMRequests = {};
   this._hasRemoteFrame = hasRemoteFrame;
+  this._nextPaintListeners = [];
 
   this._frameLoader = frameLoader;
   this._frameElement = frameLoader.QueryInterface(Ci.nsIFrameLoader).ownerElement;
@@ -213,6 +214,7 @@ function BrowserElementParent(frameLoader, hasRemoteFrame) {
   addMessageListener("error", this._fireEventFromMsg);
   addMessageListener("scroll", this._fireEventFromMsg);
   addMessageListener("firstpaint", this._fireEventFromMsg);
+  addMessageListener("nextpaint", this._recvNextPaint);
   addMessageListener("keyevent", this._fireKeyEvent);
   addMessageListener("showmodalprompt", this._handleShowModalPrompt);
   addMessageListener('got-purge-history', this._gotDOMRequestResult);
@@ -257,6 +259,8 @@ function BrowserElementParent(frameLoader, hasRemoteFrame) {
   defineMethod('stop', this._stop);
   defineMethod('purgeHistory', this._purgeHistory);
   defineMethod('getScreenshot', this._getScreenshot);
+  defineMethod('addNextPaintListener', this._addNextPaintListener);
+  defineMethod('removeNextPaintListener', this._removeNextPaintListener);
   defineDOMRequestMethod('getCanGoBack', 'get-can-go-back');
   defineDOMRequestMethod('getCanGoForward', 'get-can-go-forward');
 
@@ -594,6 +598,41 @@ BrowserElementParent.prototype = {
                                 {width: width, height: height});
   },
 
+  _recvNextPaint: function(data) {
+    let listeners = this._nextPaintListeners;
+    this._nextPaintListeners = [];
+    for (let listener of listeners) {
+      try {
+        listener();
+      } catch (e) {
+        // If a listener throws we'll continue.
+      }
+    }
+  },
+
+  _addNextPaintListener: function(listener) {
+    if (typeof listener != 'function')
+      throw Components.Exception("Invalid argument", Cr.NS_ERROR_INVALID_ARG);
+
+    if (this._nextPaintListeners.push(listener) == 1)
+      this._sendAsyncMsg('activate-next-paint-listener');
+  },
+
+  _removeNextPaintListener: function(listener) {
+    if (typeof listener != 'function')
+      throw Components.Exception("Invalid argument", Cr.NS_ERROR_INVALID_ARG);
+
+    for (let i = this._nextPaintListeners.length - 1; i >= 0; i--) {
+      if (this._nextPaintListeners[i] == listener) {
+        this._nextPaintListeners.splice(i, 1);
+        break;
+      }
+    }
+
+    if (this._nextPaintListeners.length == 0)
+      this._sendAsyncMsg('deactivate-next-paint-listener');
+  },
+
   _fireKeyEvent: function(data) {
     let evt = this._window.document.createEvent("KeyboardEvent");
     evt.initKeyEvent(data.json.type, true, true, this._window,

dom/browser-element/mochitest/Makefile.in

@@ -71,6 +71,10 @@ MOCHITEST_FILES = \
 		file_browserElement_XFrameOptionsAllowFrom.sjs \
 		browserElement_FirstPaint.js \
 		test_browserElement_inproc_FirstPaint.html \
+		browserElement_NextPaint.js \
+		test_browserElement_inproc_NextPaint.html \
+		test_browserElement_oop_NextPaint.html \
+		file_browserElement_NextPaint.html \
 		browserElement_Alert.js \
 		test_browserElement_inproc_Alert.html \
 		browserElement_AlertInFrame.js \

dom/browser-element/mochitest/browserElement_NextPaint.js

@@ -0,0 +1,45 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 808231 - Add mozbrowsernextpaint event.
+"use strict";
+
+SimpleTest.waitForExplicitFinish();
+
+function runTest() {
+  browserElementTestHelpers.setEnabledPref(true);
+  browserElementTestHelpers.addPermission();
+
+  var iframe = document.createElement('iframe');
+  iframe.mozbrowser = true;
+  document.body.appendChild(iframe);
+
+  // Add a first listener that we'll remove shortly after.
+  iframe.addNextPaintListener(wrongListener);
+
+  var gotFirstNextPaintEvent = false;
+  iframe.addNextPaintListener(function () {
+    ok(!gotFirstNextPaintEvent, 'got the first nextpaint event');
+
+    // Make sure we're only called once.
+    gotFirstNextPaintEvent = true;
+
+    iframe.addNextPaintListener(function () {
+      info('got the second nextpaint event');
+      SimpleTest.finish();
+    });
+
+    // Force the iframe to repaint.
+    SimpleTest.executeSoon(function () iframe.src += '#next');
+  });
+
+  // Remove the first listener to make sure it's not called.
+  iframe.removeNextPaintListener(wrongListener);
+  iframe.src = 'file_browserElement_NextPaint.html';
+}
+
+function wrongListener() {
+  ok(false, 'first listener should have been removed');
+}
+
+runTest();

dom/browser-element/mochitest/file_browserElement_NextPaint.html

@@ -0,0 +1,9 @@
+<html>
+<body>
+<script>
+addEventListener("hashchange", function () {
+  document.body.style.backgroundColor = "red";
+});
+</script>
+</body>
+</html>

dom/browser-element/mochitest/test_browserElement_inproc_NextPaint.html

@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 808231</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript;version=1.7" src="browserElement_NextPaint.js">
+</script>
+</body>
+</html>

dom/browser-element/mochitest/test_browserElement_oop_NextPaint.html

@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 808231</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript;version=1.7" src="browserElement_NextPaint.js">
+</script>
+</body>
+</html>