jiaojiu/node_modules/vue-awesome-mui/mui/js/mui.gestures.pinch.js

/**
 * mui gesture pinch
 * @param {type} $
 * @param {type} name
 * @returns {undefined}
 */
(function($, name) {
	var handle = function(event, touch) {
		var options = this.options;
		var session = $.gestures.session;
		switch (event.type) {
			case $.EVENT_START:
				break;
			case $.EVENT_MOVE:
				if ($.options.gestureConfig.pinch) {
					if (touch.touches.length < 2) {
						return;
					}
					if (!session.pinch) { //start
						session.pinch = true;
						$.trigger(session.target, name + 'start', touch);
					}
					$.trigger(session.target, name, touch);
					var scale = touch.scale;
					var rotation = touch.rotation;
					var lastScale = typeof touch.lastScale === 'undefined' ? 1 : touch.lastScale;
					var scaleDiff = 0.000000000001; //防止scale与lastScale相等，不触发事件的情况。
					if (scale > lastScale) { //out
						lastScale = scale - scaleDiff;
						$.trigger(session.target, name + 'out', touch);
					} //in
					else if (scale < lastScale) {
						lastScale = scale + scaleDiff;
						$.trigger(session.target, name + 'in', touch);
					}
					if (Math.abs(rotation) > options.minRotationAngle) {
						$.trigger(session.target, 'rotate', touch);
					}
				}
				break;
			case $.EVENT_END:
			case $.EVENT_CANCEL:
				if ($.options.gestureConfig.pinch && session.pinch && touch.touches.length === 2) {
					session.pinch = false;
					$.trigger(session.target, name + 'end', touch);
				}
				break;
		}
	};
	/**
	 * mui gesture pinch
	 */
	$.addGesture({
		name: name,
		index: 10,
		handle: handle,
		options: {
			minRotationAngle: 0
		}
	});
})(mui, 'pinch');