tenfourfox/dom/browser-element/BrowserElementPanning.js

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2017-04-19 07:56:45 +00:00
/* -*- tab-width: 2; indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* vim: set ts=2 sw=2 sts=2 et: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
dump("############################### browserElementPanning.js loaded\n");
var { classes: Cc, interfaces: Ci, results: Cr, utils: Cu } = Components;
Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/Geometry.jsm");
const kObservedEvents = [
"BEC:ShownModalPrompt",
"Activity:Success",
"Activity:Error"
];
const ContentPanning = {
init: function cp_init() {
addEventListener("unload",
this._unloadHandler.bind(this),
/* useCapture = */ false,
/* wantsUntrusted = */ false);
addMessageListener("Viewport:Change", this._recvViewportChange.bind(this));
addMessageListener("Gesture:DoubleTap", this._recvDoubleTap.bind(this));
addEventListener("visibilitychange", this._handleVisibilityChange.bind(this));
kObservedEvents.forEach((topic) => {
Services.obs.addObserver(this, topic, false);
});
},
observe: function cp_observe(subject, topic, data) {
this._resetHover();
},
get _domUtils() {
delete this._domUtils;
return this._domUtils = Cc['@mozilla.org/inspector/dom-utils;1']
.getService(Ci.inIDOMUtils);
},
_resetHover: function cp_resetHover() {
const kStateHover = 0x00000004;
try {
let element = content.document.createElement('foo');
this._domUtils.setContentState(element, kStateHover);
} catch(e) {}
},
_recvViewportChange: function(data) {
let metrics = data.json;
this._viewport = new Rect(metrics.x, metrics.y,
metrics.viewport.width,
metrics.viewport.height);
this._cssCompositedRect = new Rect(metrics.x, metrics.y,
metrics.cssCompositedRect.width,
metrics.cssCompositedRect.height);
this._cssPageRect = new Rect(metrics.cssPageRect.x,
metrics.cssPageRect.y,
metrics.cssPageRect.width,
metrics.cssPageRect.height);
},
_recvDoubleTap: function(data) {
data = data.json;
// We haven't received a metrics update yet; don't do anything.
if (this._viewport == null) {
return;
}
let win = content;
let element = ElementTouchHelper.anyElementFromPoint(win, data.x, data.y);
if (!element) {
this._zoomOut();
return;
}
while (element && !this._shouldZoomToElement(element))
element = element.parentNode;
if (!element) {
this._zoomOut();
} else {
const margin = 15;
let rect = ElementTouchHelper.getBoundingContentRect(element);
let cssPageRect = this._cssPageRect;
let viewport = this._viewport;
let bRect = new Rect(Math.max(cssPageRect.x, rect.x - margin),
rect.y,
rect.w + 2 * margin,
rect.h);
// constrict the rect to the screen's right edge
bRect.width = Math.min(bRect.width, cssPageRect.right - bRect.x);
// if the rect is already taking up most of the visible area and is stretching the
// width of the page, then we want to zoom out instead.
if (this._isRectZoomedIn(bRect, this._cssCompositedRect)) {
this._zoomOut();
return;
}
rect.x = Math.round(bRect.x);
rect.y = Math.round(bRect.y);
rect.w = Math.round(bRect.width);
rect.h = Math.round(bRect.height);
// if the block we're zooming to is really tall, and the user double-tapped
// more than a screenful of height from the top of it, then adjust the y-coordinate
// so that we center the actual point the user double-tapped upon. this prevents
// flying to the top of a page when double-tapping to zoom in (bug 761721).
// the 1.2 multiplier is just a little fuzz to compensate for bRect including horizontal
// margins but not vertical ones.
let cssTapY = viewport.y + data.y;
if ((bRect.height > rect.h) && (cssTapY > rect.y + (rect.h * 1.2))) {
rect.y = cssTapY - (rect.h / 2);
}
Services.obs.notifyObservers(docShell, 'browser-zoom-to-rect', JSON.stringify(rect));
}
},
_handleVisibilityChange: function(evt) {
if (!evt.target.hidden)
return;
this._resetHover();
},
_shouldZoomToElement: function(aElement) {
let win = aElement.ownerDocument.defaultView;
if (win.getComputedStyle(aElement, null).display == "inline")
return false;
if (aElement instanceof Ci.nsIDOMHTMLLIElement)
return false;
if (aElement instanceof Ci.nsIDOMHTMLQuoteElement)
return false;
return true;
},
_zoomOut: function() {
let rect = new Rect(0, 0, 0, 0);
Services.obs.notifyObservers(docShell, 'browser-zoom-to-rect', JSON.stringify(rect));
},
_isRectZoomedIn: function(aRect, aViewport) {
// This function checks to see if the area of the rect visible in the
// viewport (i.e. the "overlapArea" variable below) is approximately
// the max area of the rect we can show.
let vRect = new Rect(aViewport.x, aViewport.y, aViewport.width, aViewport.height);
let overlap = vRect.intersect(aRect);
let overlapArea = overlap.width * overlap.height;
let availHeight = Math.min(aRect.width * vRect.height / vRect.width, aRect.height);
let showing = overlapArea / (aRect.width * availHeight);
let ratioW = (aRect.width / vRect.width);
let ratioH = (aRect.height / vRect.height);
return (showing > 0.9 && (ratioW > 0.9 || ratioH > 0.9));
},
_unloadHandler: function() {
kObservedEvents.forEach((topic) => {
Services.obs.removeObserver(this, topic);
});
}
};
const ElementTouchHelper = {
anyElementFromPoint: function(aWindow, aX, aY) {
let cwu = aWindow.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
let elem = cwu.elementFromPoint(aX, aY, true, true);
let HTMLIFrameElement = Ci.nsIDOMHTMLIFrameElement;
let HTMLFrameElement = Ci.nsIDOMHTMLFrameElement;
while (elem && (elem instanceof HTMLIFrameElement || elem instanceof HTMLFrameElement)) {
let rect = elem.getBoundingClientRect();
aX -= rect.left;
aY -= rect.top;
cwu = elem.contentDocument.defaultView.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
elem = cwu.elementFromPoint(aX, aY, true, true);
}
return elem;
},
getBoundingContentRect: function(aElement) {
if (!aElement)
return {x: 0, y: 0, w: 0, h: 0};
let document = aElement.ownerDocument;
while (document.defaultView.frameElement)
document = document.defaultView.frameElement.ownerDocument;
let cwu = document.defaultView.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
let scrollX = {}, scrollY = {};
cwu.getScrollXY(false, scrollX, scrollY);
let r = aElement.getBoundingClientRect();
// step out of iframes and frames, offsetting scroll values
for (let frame = aElement.ownerDocument.defaultView; frame.frameElement && frame != content; frame = frame.parent) {
// adjust client coordinates' origin to be top left of iframe viewport
let rect = frame.frameElement.getBoundingClientRect();
let left = frame.getComputedStyle(frame.frameElement, "").borderLeftWidth;
let top = frame.getComputedStyle(frame.frameElement, "").borderTopWidth;
scrollX.value += rect.left + parseInt(left);
scrollY.value += rect.top + parseInt(top);
}
return {x: r.left + scrollX.value,
y: r.top + scrollY.value,
w: r.width,
h: r.height };
}
};