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linkHints.js
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linkHints.js
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/*
* This implements link hinting. Typing "F" will enter link-hinting mode, where all clickable items on the
* page have a hint marker displayed containing a sequence of letters. Typing those letters will select a link.
*
* In our 'default' mode, the characters we use to show link hints are a user-configurable option. By default
* they're the home row. The CSS which is used on the link hints is also a configurable option.
*
* In 'filter' mode, our link hints are numbers, and the user can narrow down the range of possibilities by
* typing the text of the link itself.
*/
var linkHints = {
hintMarkers: [],
hintMarkerContainingDiv: null,
shouldOpenInNewTab: false,
shouldOpenWithQueue: false,
// function that does the appropriate action on the selected link
linkActivator: undefined,
// While in delayMode, all keypresses have no effect.
delayMode: false,
// Handle the link hinting marker generation and matching. Must be initialized after settings have been
// loaded, so that we can retrieve the option setting.
markerMatcher: undefined,
/*
* To be called after linkHints has been generated from linkHintsBase.
*/
init: function() {
this.onKeyDownInMode = this.onKeyDownInMode.bind(this);
this.markerMatcher = settings.get('filterLinkHints') ? filterHints : alphabetHints;
},
/*
* Generate an XPath describing what a clickable element is.
* The final expression will be something like "//button | //xhtml:button | ..."
* We use translate() instead of lower-case() because Chrome only supports XPath 1.0.
*/
clickableElementsXPath: domUtils.makeXPath(["a", "area[@href]", "textarea", "button", "select",
"input[not(@type='hidden' or @disabled or @readonly)]",
"*[@onclick or @tabindex or @role='link' or @role='button' or contains(@class, 'button') or " +
"@contenteditable='' or translate(@contenteditable, 'TRUE', 'true')='true']"]),
// We need this as a top-level function because our command system doesn't yet support arguments.
activateModeToOpenInNewTab: function() { this.activateMode(true, false, false); },
activateModeToCopyLinkUrl: function() { this.activateMode(null, false, true); },
activateModeWithQueue: function() { this.activateMode(true, true, false); },
activateMode: function(openInNewTab, withQueue, copyLinkUrl) {
if (!document.getElementById('vimiumLinkHintCss'))
// linkHintCss is declared by vimiumFrontend.js and contains the user supplied css overrides.
addCssToPage(linkHintCss, 'vimiumLinkHintCss');
this.setOpenLinkMode(openInNewTab, withQueue, copyLinkUrl);
this.buildLinkHints();
handlerStack.push({ // handlerStack is declared by vimiumFrontend.js
keydown: this.onKeyDownInMode,
// trap all key events
keypress: function() { return false; },
keyup: function() { return false; }
});
},
setOpenLinkMode: function(openInNewTab, withQueue, copyLinkUrl) {
this.shouldOpenInNewTab = openInNewTab;
this.shouldOpenWithQueue = withQueue;
if (openInNewTab || withQueue) {
if (openInNewTab)
HUD.show("Open link in new tab");
else if (withQueue)
HUD.show("Open multiple links in a new tab");
this.linkActivator = function(link) {
// When "clicking" on a link, dispatch the event with the appropriate meta key (CMD on Mac, CTRL on windows)
// to open it in a new tab if necessary.
domUtils.simulateClick(link, { metaKey: platform == "Mac", ctrlKey: platform != "Mac" });
}
} else if (copyLinkUrl) {
HUD.show("Copy link URL to Clipboard");
this.linkActivator = function(link) {
chrome.extension.sendRequest({handler: 'copyToClipboard', data: link.href});
}
} else {
HUD.show("Open link in current tab");
// When we're opening the link in the current tab, don't navigate to the selected link immediately;
// we want to give the user some time to notice which link has received focus.
this.linkActivator = function(link) {
setTimeout(domUtils.simulateClick.bind(domUtils, link), 400);
}
}
},
/*
* Builds and displays link hints for every visible clickable item on the page.
*/
buildLinkHints: function() {
var visibleElements = this.getVisibleClickableElements();
this.hintMarkers = this.markerMatcher.getHintMarkers(visibleElements);
// Note(philc): Append these markers as top level children instead of as child nodes to the link itself,
// because some clickable elements cannot contain children, e.g. submit buttons. This has the caveat
// that if you scroll the page and the link has position=fixed, the marker will not stay fixed.
// Also note that adding these nodes to document.body all at once is significantly faster than one-by-one.
this.hintMarkerContainingDiv = document.createElement("div");
this.hintMarkerContainingDiv.id = "vimiumHintMarkerContainer";
this.hintMarkerContainingDiv.className = "vimiumReset";
for (var i = 0; i < this.hintMarkers.length; i++)
this.hintMarkerContainingDiv.appendChild(this.hintMarkers[i]);
// sometimes this is triggered before documentElement is created
// TODO(int3): fail more gracefully?
if (document.documentElement)
document.documentElement.appendChild(this.hintMarkerContainingDiv);
else
this.deactivateMode();
},
/*
* Returns all clickable elements that are not hidden and are in the current viewport.
* We prune invisible elements partly for performance reasons, but moreso it's to decrease the number
* of digits needed to enumerate all of the links on screen.
*/
getVisibleClickableElements: function() {
var resultSet = domUtils.evaluateXPath(this.clickableElementsXPath, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE);
var visibleElements = [];
// Find all visible clickable elements.
for (var i = 0, count = resultSet.snapshotLength; i < count; i++) {
var element = resultSet.snapshotItem(i);
var clientRect = domUtils.getVisibleClientRect(element, clientRect);
if (clientRect !== null)
visibleElements.push({element: element, rect: clientRect});
if (element.localName === "area") {
var map = element.parentElement;
if (!map) continue;
var img = document.querySelector("img[usemap='#" + map.getAttribute("name") + "']");
if (!img) continue;
var imgClientRects = img.getClientRects();
if (imgClientRects.length == 0) continue;
var c = element.coords.split(/,/);
var coords = [parseInt(c[0], 10), parseInt(c[1], 10), parseInt(c[2], 10), parseInt(c[3], 10)];
var rect = {
top: imgClientRects[0].top + coords[1],
left: imgClientRects[0].left + coords[0],
right: imgClientRects[0].left + coords[2],
bottom: imgClientRects[0].top + coords[3],
width: coords[2] - coords[0],
height: coords[3] - coords[1]
};
visibleElements.push({element: element, rect: rect});
}
}
return visibleElements;
},
/*
* Handles shift and esc keys. The other keys are passed to markerMatcher.matchHintsByKey.
*/
onKeyDownInMode: function(event) {
if (this.delayMode)
return;
var that = this;
if (event.keyCode == keyCodes.shiftKey && this.shouldOpenInNewTab !== null) {
// Toggle whether to open link in a new or current tab.
this.setOpenLinkMode(!this.shouldOpenInNewTab, this.shouldOpenWithQueue, false);
handlerStack.push({
keyup: function(event) {
if (event.keyCode !== keyCodes.shiftKey) return;
linkHints.setOpenLinkMode(!that.shouldOpenInNewTab, that.shouldOpenWithQueue, false);
handlerStack.pop();
}
});
}
// TODO(philc): Ignore keys that have modifiers.
if (isEscape(event)) {
this.deactivateMode();
} else {
var keyResult = this.markerMatcher.matchHintsByKey(event, this.hintMarkers);
var linksMatched = keyResult.linksMatched;
var delay = keyResult.delay !== undefined ? keyResult.delay : 0;
if (linksMatched.length == 0) {
this.deactivateMode();
} else if (linksMatched.length == 1) {
this.activateLink(linksMatched[0].clickableItem, delay);
} else {
for (var i in this.hintMarkers)
this.hideMarker(this.hintMarkers[i]);
for (var i in linksMatched)
this.showMarker(linksMatched[i], this.markerMatcher.hintKeystrokeQueue.length);
}
}
},
/*
* When only one link hint remains, this function activates it in the appropriate way.
*/
activateLink: function(matchedLink, delay) {
var that = this;
this.delayMode = true;
if (domUtils.isSelectable(matchedLink)) {
domUtils.simulateSelect(matchedLink);
this.deactivateMode(delay, function() { that.delayMode = false; });
} else {
// TODO figure out which other input elements should not receive focus
if (matchedLink.nodeName.toLowerCase() === 'input' &&
matchedLink.type !== 'button')
matchedLink.focus();
domUtils.flashElement(matchedLink);
this.linkActivator(matchedLink);
if (this.shouldOpenWithQueue) {
this.deactivateMode(delay, function() {
that.delayMode = false;
that.activateModeWithQueue();
});
} else {
this.deactivateMode(delay, function() { that.delayMode = false; });
}
}
},
/*
* Shows the marker, highlighting matchingCharCount characters.
*/
showMarker: function(linkMarker, matchingCharCount) {
linkMarker.style.display = "";
for (var j = 0, count = linkMarker.childNodes.length; j < count; j++)
(j < matchingCharCount) ? linkMarker.childNodes[j].classList.add("matchingCharacter") :
linkMarker.childNodes[j].classList.remove("matchingCharacter");
},
hideMarker: function(linkMarker) {
linkMarker.style.display = "none";
},
/*
* If called without arguments, it executes immediately. Othewise, it
* executes after 'delay' and invokes 'callback' when it is finished.
*/
deactivateMode: function(delay, callback) {
var that = this;
function deactivate() {
if (that.markerMatcher.deactivate)
that.markerMatcher.deactivate();
if (that.hintMarkerContainingDiv)
that.hintMarkerContainingDiv.parentNode.removeChild(that.hintMarkerContainingDiv);
that.hintMarkerContainingDiv = null;
that.hintMarkers = [];
handlerStack.pop();
HUD.hide();
}
// we invoke the deactivate() function directly instead of using setTimeout(callback, 0) so that
// deactivateMode can be tested synchronously
if (!delay) {
deactivate();
if (callback) callback();
} else {
setTimeout(function() { deactivate(); if (callback) callback(); }, delay);
}
},
};
var alphabetHints = {
hintKeystrokeQueue: [],
logXOfBase: function(x, base) { return Math.log(x) / Math.log(base); },
getHintMarkers: function(visibleElements) {
var hintStrings = this.hintStrings(visibleElements.length);
var hintMarkers = [];
for (var i = 0, count = visibleElements.length; i < count; i++) {
var marker = hintUtils.createMarkerFor(visibleElements[i]);
marker.hintString = hintStrings[i];
marker.innerHTML = hintUtils.spanWrap(marker.hintString.toUpperCase());
hintMarkers.push(marker);
}
return hintMarkers;
},
/*
* Returns a list of hint strings which will uniquely identify the given number of links. The hint strings
* may be of different lengths.
*/
hintStrings: function(linkCount) {
var linkHintCharacters = settings.get("linkHintCharacters");
// Determine how many digits the link hints will require in the worst case. Usually we do not need
// all of these digits for every link single hint, so we can show shorter hints for a few of the links.
var digitsNeeded = Math.ceil(this.logXOfBase(linkCount, linkHintCharacters.length));
// Short hints are the number of hints we can possibly show which are (digitsNeeded - 1) digits in length.
var shortHintCount = Math.floor(
(Math.pow(linkHintCharacters.length, digitsNeeded) - linkCount) /
linkHintCharacters.length);
var longHintCount = linkCount - shortHintCount;
var hintStrings = [];
if (digitsNeeded > 1)
for (var i = 0; i < shortHintCount; i++)
hintStrings.push(this.numberToHintString(i, digitsNeeded - 1, linkHintCharacters));
var start = shortHintCount * linkHintCharacters.length;
for (var i = start; i < start + longHintCount; i++)
hintStrings.push(this.numberToHintString(i, digitsNeeded, linkHintCharacters));
return this.shuffleHints(hintStrings, linkHintCharacters.length);
},
/*
* This shuffles the given set of hints so that they're scattered -- hints starting with the same character
* will be spread evenly throughout the array.
*/
shuffleHints: function(hints, characterSetLength) {
var buckets = [], i = 0;
for (i = 0; i < characterSetLength; i++)
buckets[i] = []
for (i = 0; i < hints.length; i++)
buckets[i % buckets.length].push(hints[i]);
var result = [];
for (i = 0; i < buckets.length; i++)
result = result.concat(buckets[i]);
return result;
},
/*
* Converts a number like "8" into a hint string like "JK". This is used to sequentially generate all of
* the hint text. The hint string will be "padded with zeroes" to ensure its length is equal to numHintDigits.
*/
numberToHintString: function(number, numHintDigits, characterSet) {
var base = characterSet.length;
var hintString = [];
var remainder = 0;
do {
remainder = number % base;
hintString.unshift(characterSet[remainder]);
number -= remainder;
number /= Math.floor(base);
} while (number > 0);
// Pad the hint string we're returning so that it matches numHintDigits.
// Note: the loop body changes hintString.length, so the original length must be cached!
var hintStringLength = hintString.length;
for (var i = 0; i < numHintDigits - hintStringLength; i++)
hintString.unshift(characterSet[0]);
return hintString.join("");
},
matchHintsByKey: function(event, hintMarkers) {
var keyChar = getKeyChar(event);
if (event.keyCode == keyCodes.backspace || event.keyCode == keyCodes.deleteKey) {
if (!this.hintKeystrokeQueue.pop())
return { linksMatched: [] };
} else if (keyChar && settings.get('linkHintCharacters').indexOf(keyChar) >= 0) {
this.hintKeystrokeQueue.push(keyChar);
}
var matchString = this.hintKeystrokeQueue.join("");
var linksMatched = hintMarkers.filter(function(linkMarker) {
return linkMarker.hintString.indexOf(matchString) == 0;
});
return { linksMatched: linksMatched };
},
deactivate: function() {
this.hintKeystrokeQueue = [];
}
};
var filterHints = {
hintKeystrokeQueue: [],
linkTextKeystrokeQueue: [],
labelMap: {},
/*
* Generate a map of input element => label
*/
generateLabelMap: function() {
var labels = document.querySelectorAll("label");
for (var i = 0, count = labels.length; i < count; i++) {
var forElement = labels[i].getAttribute("for");
if (forElement) {
var labelText = labels[i].textContent.trim();
// remove trailing : commonly found in labels
if (labelText[labelText.length-1] == ":")
labelText = labelText.substr(0, labelText.length-1);
this.labelMap[forElement] = labelText;
}
}
},
generateHintString: function(linkHintNumber) {
return (linkHintNumber + 1).toString();
},
generateLinkText: function(element) {
var linkText = "";
var showLinkText = false;
// toLowerCase is necessary as html documents return 'IMG'
// and xhtml documents return 'img'
var nodeName = element.nodeName.toLowerCase();
if (nodeName == "input") {
if (this.labelMap[element.id]) {
linkText = this.labelMap[element.id];
showLinkText = true;
} else if (element.type != "password") {
linkText = element.value;
}
// check if there is an image embedded in the <a> tag
} else if (nodeName == "a" && !element.textContent.trim()
&& element.firstElementChild
&& element.firstElementChild.nodeName.toLowerCase() == "img") {
linkText = element.firstElementChild.alt || element.firstElementChild.title;
if (linkText)
showLinkText = true;
} else {
linkText = element.textContent || element.innerHTML;
}
return { text: linkText, show: showLinkText };
},
renderMarker: function(marker) {
marker.innerHTML = hintUtils.spanWrap(marker.hintString +
(marker.showLinkText ? ": " + marker.linkText : ""));
},
getHintMarkers: function(visibleElements) {
this.generateLabelMap();
var hintMarkers = [];
for (var i = 0, count = visibleElements.length; i < count; i++) {
var marker = hintUtils.createMarkerFor(visibleElements[i]);
marker.hintString = this.generateHintString(i);
var linkTextObject = this.generateLinkText(marker.clickableItem);
marker.linkText = linkTextObject.text;
marker.showLinkText = linkTextObject.show;
this.renderMarker(marker);
hintMarkers.push(marker);
}
return hintMarkers;
},
matchHintsByKey: function(event, hintMarkers) {
var keyChar = getKeyChar(event);
var delay = 0;
var userIsTypingLinkText = false;
if (event.keyCode == keyCodes.enter) {
// activate the lowest-numbered link hint that is visible
for (var i = 0, count = hintMarkers.length; i < count; i++)
if (hintMarkers[i].style.display != 'none') {
return { linksMatched: [ hintMarkers[i] ] };
}
} else if (event.keyCode == keyCodes.backspace || event.keyCode == keyCodes.deleteKey) {
// backspace clears hint key queue first, then acts on link text key queue.
// if both queues are empty. exit hinting mode
if (!this.hintKeystrokeQueue.pop() && !this.linkTextKeystrokeQueue.pop())
return { linksMatched: [] };
} else if (keyChar) {
if (/[0-9]/.test(keyChar))
this.hintKeystrokeQueue.push(keyChar);
else {
// since we might renumber the hints, the current hintKeyStrokeQueue
// should be rendered invalid (i.e. reset).
this.hintKeystrokeQueue = [];
this.linkTextKeystrokeQueue.push(keyChar);
userIsTypingLinkText = true;
}
}
// at this point, linkTextKeystrokeQueue and hintKeystrokeQueue have been updated to reflect the latest
// input. use them to filter the link hints accordingly.
var linksMatched = this.filterLinkHints(hintMarkers);
var matchString = this.hintKeystrokeQueue.join("");
linksMatched = linksMatched.filter(function(linkMarker) {
return !linkMarker.filtered && linkMarker.hintString.indexOf(matchString) == 0;
});
if (linksMatched.length == 1 && userIsTypingLinkText) {
// In filter mode, people tend to type out words past the point
// needed for a unique match. Hence we should avoid passing
// control back to command mode immediately after a match is found.
var delay = 200;
}
return { linksMatched: linksMatched, delay: delay };
},
/*
* Marks the links that do not match the linkText search string with the 'filtered' DOM property. Renumbers
* the remainder if necessary.
*/
filterLinkHints: function(hintMarkers) {
var linksMatched = [];
var linkSearchString = this.linkTextKeystrokeQueue.join("");
for (var i = 0; i < hintMarkers.length; i++) {
var linkMarker = hintMarkers[i];
var matchedLink = linkMarker.linkText.toLowerCase().indexOf(linkSearchString.toLowerCase()) >= 0;
if (!matchedLink) {
linkMarker.filtered = true;
} else {
linkMarker.filtered = false;
var oldHintString = linkMarker.hintString;
linkMarker.hintString = this.generateHintString(linksMatched.length);
if (linkMarker.hintString != oldHintString)
this.renderMarker(linkMarker);
linksMatched.push(linkMarker);
}
}
return linksMatched;
},
deactivate: function(delay, callback) {
this.hintKeystrokeQueue = [];
this.linkTextKeystrokeQueue = [];
this.labelMap = {};
}
};
var hintUtils = {
/*
* Make each hint character a span, so that we can highlight the typed characters as you type them.
*/
spanWrap: function(hintString) {
var innerHTML = [];
for (var i = 0; i < hintString.length; i++)
innerHTML.push("<span class='vimiumReset'>" + hintString[i] + "</span>");
return innerHTML.join("");
},
/*
* Creates a link marker for the given link.
*/
createMarkerFor: function(link) {
var marker = document.createElement("div");
marker.className = "vimiumReset internalVimiumHintMarker vimiumHintMarker";
marker.clickableItem = link.element;
var clientRect = link.rect;
marker.style.left = clientRect.left + window.scrollX + "px";
marker.style.top = clientRect.top + window.scrollY + "px";
return marker;
}
};