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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview A collection of utility methods for UberPage and its contained
* pages.
*/
cr.define('uber', function() {
/**
* Fixed position header elements on the page to be shifted by handleScroll.
* @type {NodeList}
*/
var headerElements;
/**
* This should be called by uber content pages when DOM content has loaded.
*/
function onContentFrameLoaded() {
headerElements = document.getElementsByTagName('header');
document.addEventListener('scroll', handleScroll);
// Prevent the navigation from being stuck in a disabled state when a
// content page is reloaded while an overlay is visible (crbug.com/246939).
invokeMethodOnParent('stopInterceptingEvents');
// Trigger the scroll handler to tell the navigation if our page started
// with some scroll (happens when you use tab restore).
handleScroll();
window.addEventListener('message', handleWindowMessage);
}
/**
* Handles scroll events on the document. This adjusts the position of all
* headers and updates the parent frame when the page is scrolled.
* @private
*/
function handleScroll() {
var scrollLeft = scrollLeftForDocument(document);
var offset = scrollLeft * -1;
for (var i = 0; i < headerElements.length; i++) {
// As a workaround for http://crbug.com/231830, set the transform to
// 'none' rather than 0px.
headerElements[i].style.webkitTransform = offset ?
'translateX(' + offset + 'px)' : 'none';
}
invokeMethodOnParent('adjustToScroll', scrollLeft);
};
/**
* Handles 'message' events on window.
* @param {Event} e The message event.
*/
function handleWindowMessage(e) {
if (e.data.method === 'frameSelected')
handleFrameSelected();
else if (e.data.method === 'mouseWheel')
handleMouseWheel(e.data.params);
}
/**
* This is called when a user selects this frame via the navigation bar
* frame (and is triggered via postMessage() from the uber page).
* @private
*/
function handleFrameSelected() {
setScrollTopForDocument(document, 0);
}
/**
* Called when a user mouse wheels (or trackpad scrolls) over the nav frame.
* The wheel event is forwarded here and we scroll the body.
* There's no way to figure out the actual scroll amount for a given delta.
* It differs for every platform and even initWebKitWheelEvent takes a
* pixel amount instead of a wheel delta. So we just choose something
* reasonable and hope no one notices the difference.
* @param {Object} params A structure that holds wheel deltas in X and Y.
*/
function handleMouseWheel(params) {
window.scrollBy(-params.deltaX * 49 / 120, -params.deltaY * 49 / 120);
}
/**
* Invokes a method on the parent window (UberPage). This is a convenience
* method for API calls into the uber page.
* @param {string} method The name of the method to invoke.
* @param {Object=} opt_params Optional property bag of parameters to pass to
* the invoked method.
* @private
*/
function invokeMethodOnParent(method, opt_params) {
if (window.location == window.parent.location)
return;
invokeMethodOnWindow(window.parent, method, opt_params, 'chrome://chrome');
}
/**
* Invokes a method on the target window.
* @param {string} method The name of the method to invoke.
* @param {Object=} opt_params Optional property bag of parameters to pass to
* the invoked method.
* @param {string=} opt_url The origin of the target window.
* @private
*/
function invokeMethodOnWindow(targetWindow, method, opt_params, opt_url) {
var data = {method: method, params: opt_params};
targetWindow.postMessage(data, opt_url ? opt_url : '*');
}
return {
invokeMethodOnParent: invokeMethodOnParent,
invokeMethodOnWindow: invokeMethodOnWindow,
onContentFrameLoaded: onContentFrameLoaded,
};
});
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