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+'use strict';
+
+/**
+ * @ngdoc directive
+ * @name ngMobile.directive:ngTap
+ *
+ * @description
+ * Specify custom behavior when element is tapped on a touchscreen device.
+ * A tap is a brief, down-and-up touch without much motion.
+ *
+ * @element ANY
+ * @param {expression} ngClick {@link guide/expression Expression} to evaluate
+ * upon tap. (Event object is available as `$event`)
+ *
+ * @example
+ <doc:example>
+ <doc:source>
+ <button ng-tap="count = count + 1" ng-init="count=0">
+ Increment
+ </button>
+ count: {{ count }}
+ </doc:source>
+ </doc:example>
+ */
+
+ngMobile.config(function($provide) {
+ $provide.decorator('ngClickDirective', function($delegate) {
+ // drop the default ngClick directive
+ $delegate.shift();
+ return $delegate;
+ });
+});
+
+ngMobile.directive('ngClick', ['$parse', '$timeout', '$rootElement',
+ function($parse, $timeout, $rootElement) {
+ var TAP_DURATION = 750; // Shorter than 750ms is a tap, longer is a taphold or drag.
+ var MOVE_TOLERANCE = 12; // 12px seems to work in most mobile browsers.
+ var PREVENT_DURATION = 2500; // 2.5 seconds maximum from preventGhostClick call to click
+ var CLICKBUSTER_THRESHOLD = 25; // 25 pixels in any dimension is the limit for busting clicks.
+ var lastPreventedTime;
+ var touchCoordinates;
+
+
+ // TAP EVENTS AND GHOST CLICKS
+ //
+ // Why tap events?
+ // Mobile browsers detect a tap, then wait a moment (usually ~300ms) to see if you're
+ // double-tapping, and then fire a click event.
+ //
+ // This delay sucks and makes mobile apps feel unresponsive.
+ // So we detect touchstart, touchmove, touchcancel and touchend ourselves and determine when
+ // the user has tapped on something.
+ //
+ // What happens when the browser then generates a click event?
+ // The browser, of course, also detects the tap and fires a click after a delay. This results in
+ // tapping/clicking twice. So we do "clickbusting" to prevent it.
+ //
+ // How does it work?
+ // We attach global touchstart and click handlers, that run during the capture (early) phase.
+ // So the sequence for a tap is:
+ // - global touchstart: Sets an "allowable region" at the point touched.
+ // - element's touchstart: Starts a touch
+ // (- touchmove or touchcancel ends the touch, no click follows)
+ // - element's touchend: Determines if the tap is valid (didn't move too far away, didn't hold
+ // too long) and fires the user's tap handler. The touchend also calls preventGhostClick().
+ // - preventGhostClick() removes the allowable region the global touchstart created.
+ // - The browser generates a click event.
+ // - The global click handler catches the click, and checks whether it was in an allowable region.
+ // - If preventGhostClick was called, the region will have been removed, the click is busted.
+ // - If the region is still there, the click proceeds normally. Therefore clicks on links and
+ // other elements without ngTap on them work normally.
+ //
+ // This is an ugly, terrible hack!
+ // Yeah, tell me about it. The alternatives are using the slow click events, or making our users
+ // deal with the ghost clicks, so I consider this the least of evils. Fortunately Angular
+ // encapsulates this ugly logic away from the user.
+ //
+ // Why not just put click handlers on the element?
+ // We do that too, just to be sure. The problem is that the tap event might have caused the DOM
+ // to change, so that the click fires in the same position but something else is there now. So
+ // the handlers are global and care only about coordinates and not elements.
+
+ // Checks if the coordinates are close enough to be within the region.
+ function hit(x1, y1, x2, y2) {
+ return Math.abs(x1 - x2) < CLICKBUSTER_THRESHOLD && Math.abs(y1 - y2) < CLICKBUSTER_THRESHOLD;
+ }
+
+ // Checks a list of allowable regions against a click location.
+ // Returns true if the click should be allowed.
+ // Splices out the allowable region from the list after it has been used.
+ function checkAllowableRegions(touchCoordinates, x, y) {
+ for (var i = 0; i < touchCoordinates.length; i += 2) {
+ if (hit(touchCoordinates[i], touchCoordinates[i+1], x, y)) {
+ touchCoordinates.splice(i, i + 2);
+ return true; // allowable region
+ }
+ }
+ return false; // No allowable region; bust it.
+ }
+
+ // Global click handler that prevents the click if it's in a bustable zone and preventGhostClick
+ // was called recently.
+ function onClick(event) {
+ if (Date.now() - lastPreventedTime > PREVENT_DURATION) {
+ return; // Too old.
+ }
+
+ var touches = event.touches && event.touches.length ? event.touches : [event];
+ var x = touches[0].clientX;
+ var y = touches[0].clientY;
+ // Work around desktop Webkit quirk where clicking a label will fire two clicks (on the label
+ // and on the input element). Depending on the exact browser, this second click we don't want
+ // to bust has either (0,0) or negative coordinates.
+ if (x < 1 && y < 1) {
+ return; // offscreen
+ }
+
+ // Look for an allowable region containing this click.
+ // If we find one, that means it was created by touchstart and not removed by
+ // preventGhostClick, so we don't bust it.
+ if (checkAllowableRegions(touchCoordinates, x, y)) {
+ return;
+ }
+
+ // If we didn't find an allowable region, bust the click.
+ event.stopPropagation();
+ event.preventDefault();
+ }
+
+
+ // Global touchstart handler that creates an allowable region for a click event.
+ // This allowable region can be removed by preventGhostClick if we want to bust it.
+ function onTouchStart(event) {
+ var touches = event.touches && event.touches.length ? event.touches : [event];
+ var x = touches[0].clientX;
+ var y = touches[0].clientY;
+ touchCoordinates.push(x, y);
+
+ $timeout(function() {
+ // Remove the allowable region.
+ for (var i = 0; i < touchCoordinates.length; i += 2) {
+ if (touchCoordinates[i] == x && touchCoordinates[i+1] == y) {
+ touchCoordinates.splice(i, i + 2);
+ return;
+ }
+ }
+ }, PREVENT_DURATION, false);
+ }
+
+ // On the first call, attaches some event handlers. Then whenever it gets called, it creates a
+ // zone around the touchstart where clicks will get busted.
+ function preventGhostClick(x, y) {
+ if (!touchCoordinates) {
+ $rootElement[0].addEventListener('click', onClick, true);
+ $rootElement[0].addEventListener('touchstart', onTouchStart, true);
+ touchCoordinates = [];
+ }
+
+ lastPreventedTime = Date.now();
+
+ checkAllowableRegions(touchCoordinates, x, y);
+ }
+
+ // Actual linking function.
+ return function(scope, element, attr) {
+ var expressionFn = $parse(attr.ngClick),
+ tapping = false,
+ tapElement, // Used to blur the element after a tap.
+ startTime, // Used to check if the tap was held too long.
+ touchStartX,
+ touchStartY;
+
+ function resetState() {
+ tapping = false;
+ }
+
+ element.bind('touchstart', function(event) {
+ tapping = true;
+ tapElement = event.target ? event.target : event.srcElement; // IE uses srcElement.
+ // Hack for Safari, which can target text nodes instead of containers.
+ if(tapElement.nodeType == 3) {
+ tapElement = tapElement.parentNode;
+ }
+
+ startTime = Date.now();
+
+ var touches = event.touches && event.touches.length ? event.touches : [event];
+ var e = touches[0].originalEvent || touches[0];
+ touchStartX = e.clientX;
+ touchStartY = e.clientY;
+ });
+
+ element.bind('touchmove', function(event) {
+ resetState();
+ });
+
+ element.bind('touchcancel', function(event) {
+ resetState();
+ });
+
+ element.bind('touchend', function(event) {
+ var diff = Date.now() - startTime;
+
+ var touches = (event.changedTouches && event.changedTouches.length) ? event.changedTouches :
+ ((event.touches && event.touches.length) ? event.touches : [event]);
+ var e = touches[0].originalEvent || touches[0];
+ var x = e.clientX;
+ var y = e.clientY;
+ var dist = Math.sqrt( Math.pow(x - touchStartX, 2) + Math.pow(y - touchStartY, 2) );
+
+ if (tapping && diff < TAP_DURATION && dist < MOVE_TOLERANCE) {
+ // Call preventGhostClick so the clickbuster will catch the corresponding click.
+ preventGhostClick(x, y);
+
+ // Blur the focused element (the button, probably) before firing the callback.
+ // This doesn't work perfectly on Android Chrome, but seems to work elsewhere.
+ // I couldn't get anything to work reliably on Android Chrome.
+ if (tapElement) {
+ tapElement.blur();
+ }
+
+ scope.$apply(function() {
+ // TODO(braden): This is sending the touchend, not a tap or click. Is that kosher?
+ expressionFn(scope, {$event: event});
+ });
+ }
+ tapping = false;
+ });
+
+ // Hack for iOS Safari's benefit. It goes searching for onclick handlers and is liable to click
+ // something else nearby.
+ element.onclick = function(event) { };
+
+ // Fallback click handler.
+ // Busted clicks don't get this far, and adding this handler allows ng-tap to be used on
+ // desktop as well, to allow more portable sites.
+ element.bind('click', function(event) {
+ scope.$apply(function() {
+ expressionFn(scope, {$event: event});
+ });
+ });
+ };
+}]);
+