/**
* Provide a simple Flick plugin, which can be used along with the "flick" gesture event, to
* animate the motion of the host node in response to a (mouse or touch) flick gesture.
*
* <p>The current implementation is designed to move the node, relative to the bounds of a parent node and is suitable
* for scroll/carousel type implementations. Future versions will remove that constraint, to allow open ended movement within
* the document.</p>
*
* @module node-flick
*/
var HOST = "host",
PARENT_NODE = "parentNode",
BOUNDING_BOX = "boundingBox",
OFFSET_HEIGHT = "offsetHeight",
OFFSET_WIDTH = "offsetWidth",
SCROLL_HEIGHT = "scrollHeight",
SCROLL_WIDTH = "scrollWidth",
BOUNCE = "bounce",
MIN_DISTANCE = "minDistance",
MIN_VELOCITY = "minVelocity",
BOUNCE_DISTANCE = "bounceDistance",
DECELERATION = "deceleration",
STEP = "step",
DURATION = "duration",
EASING = "easing",
FLICK = "flick",
getClassName = Y.ClassNameManager.getClassName;
/**
* A plugin class which can be used to animate the motion of a node, in response to a flick gesture.
*
* @class Flick
* @namespace Plugin
* @param {Object} config The initial attribute values for the plugin
*/
function Flick(config) {
Flick.superclass.constructor.apply(this, arguments);
}
Flick.ATTRS = {
/**
* Drag coefficent for inertial scrolling. The closer to 1 this
* value is, the less friction during scrolling.
*
* @attribute deceleration
* @default 0.98
*/
deceleration : {
value: 0.98
},
/**
* Drag coefficient for intertial scrolling at the upper
* and lower boundaries of the scrollview. Set to 0 to
* disable "rubber-banding".
*
* @attribute bounce
* @type Number
* @default 0.7
*/
bounce : {
value: 0.7
},
/**
* The bounce distance in pixels
*
* @attribute bounceDistance
* @type Number
* @default 150
*/
bounceDistance : {
value: 150
},
/**
* The minimum flick gesture velocity (px/ms) at which to trigger the flick response
*
* @attribute minVelocity
* @type Number
* @default 0
*/
minVelocity : {
value: 0
},
/**
* The minimum flick gesture distance (px) for which to trigger the flick response
*
* @attribute minVelocity
* @type Number
* @default 10
*/
minDistance : {
value: 10
},
/**
* The constraining box relative to which the flick animation and bounds should be calculated.
*
* @attribute boundingBox
* @type Node
* @default parentNode
*/
boundingBox : {
valueFn : function() {
return this.get(HOST).get(PARENT_NODE);
}
},
/**
* Time between flick animation frames.
*
* @attribute step
* @type Number
* @default 10
*/
step : {
value:10
},
/**
* The custom duration to apply to the flick animation. By default,
* the animation duration is controlled by the deceleration factor.
*
* @attribute duration
* @type Number
* @default null
*/
duration : {
value:null
},
/**
* The custom transition easing to use for the flick animation. If not
* provided defaults to internally to Flick.EASING, or Flick.SNAP_EASING based
* on whether or not we're animating the flick or bounce step.
*
* @attribute easing
* @type String
* @default null
*/
easing : {
value:null
}
};
/**
* The NAME of the Flick class. Used to prefix events generated
* by the plugin.
*
* @property NAME
* @static
* @type String
* @default "pluginFlick"
*/
Flick.NAME = "pluginFlick";
/**
* The namespace for the plugin. This will be the property on the node, which will
* reference the plugin instance, when it's plugged in.
*
* @property NS
* @static
* @type String
* @default "flick"
*/
Flick.NS = "flick";
Y.extend(Flick, Y.Plugin.Base, {
/**
* The initializer lifecycle implementation.
*
* @method initializer
* @param {Object} config The user configuration for the plugin
*/
initializer : function(config) {
this._node = this.get(HOST);
this._renderClasses();
this.setBounds();
this._node.on(FLICK, Y.bind(this._onFlick, this), {
minDistance : this.get(MIN_DISTANCE),
minVelocity : this.get(MIN_VELOCITY)
});
},
/**
* Sets the min/max boundaries for the flick animation,
* based on the boundingBox dimensions.
*
* @method setBounds
*/
setBounds : function () {
var box = this.get(BOUNDING_BOX),
node = this._node,
boxHeight = box.get(OFFSET_HEIGHT),
boxWidth = box.get(OFFSET_WIDTH),
contentHeight = node.get(SCROLL_HEIGHT),
contentWidth = node.get(SCROLL_WIDTH);
if (contentHeight > boxHeight) {
this._maxY = contentHeight - boxHeight;
this._minY = 0;
this._scrollY = true;
}
if (contentWidth > boxWidth) {
this._maxX = contentWidth - boxWidth;
this._minX = 0;
this._scrollX = true;
}
this._x = this._y = 0;
node.set("top", this._y + "px");
node.set("left", this._x + "px");
},
/**
* Adds the CSS classes, necessary to set up overflow/position properties on the
* node and boundingBox.
*
* @method _renderClasses
* @protected
*/
_renderClasses : function() {
this.get(BOUNDING_BOX).addClass(Flick.CLASS_NAMES.box);
this._node.addClass(Flick.CLASS_NAMES.content);
},
/**
* The flick event listener. Kicks off the flick animation.
*
* @method _onFlick
* @param e {EventFacade} The flick event facade, containing e.flick.distance, e.flick.velocity etc.
* @protected
*/
_onFlick: function(e) {
this._v = e.flick.velocity;
this._flick = true;
this._flickAnim();
},
/**
* Executes a single frame in the flick animation
*
* @method _flickFrame
* @protected
*/
_flickAnim: function() {
var y = this._y,
x = this._x,
maxY = this._maxY,
minY = this._minY,
maxX = this._maxX,
minX = this._minX,
velocity = this._v,
step = this.get(STEP),
deceleration = this.get(DECELERATION),
bounce = this.get(BOUNCE);
this._v = (velocity * deceleration);
this._snapToEdge = false;
if (this._scrollX) {
x = x - (velocity * step);
}
if (this._scrollY) {
y = y - (velocity * step);
}
if (Math.abs(velocity).toFixed(4) <= Flick.VELOCITY_THRESHOLD) {
this._flick = false;
this._killTimer(!(this._exceededYBoundary || this._exceededXBoundary));
if (this._scrollX) {
if (x < minX) {
this._snapToEdge = true;
this._setX(minX);
} else if (x > maxX) {
this._snapToEdge = true;
this._setX(maxX);
}
}
if (this._scrollY) {
if (y < minY) {
this._snapToEdge = true;
this._setY(minY);
} else if (y > maxY) {
this._snapToEdge = true;
this._setY(maxY);
}
}
} else {
if (this._scrollX && (x < minX || x > maxX)) {
this._exceededXBoundary = true;
this._v *= bounce;
}
if (this._scrollY && (y < minY || y > maxY)) {
this._exceededYBoundary = true;
this._v *= bounce;
}
if (this._scrollX) {
this._setX(x);
}
if (this._scrollY) {
this._setY(y);
}
this._flickTimer = Y.later(step, this, this._flickAnim);
}
},
/**
* Internal utility method to set the X offset position
*
* @method _setX
* @param {Number} val
* @private
*/
_setX : function(val) {
this._move(val, null, this.get(DURATION), this.get(EASING));
},
/**
* Internal utility method to set the Y offset position
*
* @method _setY
* @param {Number} val
* @private
*/
_setY : function(val) {
this._move(null, val, this.get(DURATION), this.get(EASING));
},
/**
* Internal utility method to move the node to a given XY position,
* using transitions, if specified.
*
* @method _move
* @param {Number} x The X offset position
* @param {Number} y The Y offset position
* @param {Number} duration The duration to use for the transition animation
* @param {String} easing The easing to use for the transition animation.
*
* @private
*/
_move: function(x, y, duration, easing) {
if (x !== null) {
x = this._bounce(x);
} else {
x = this._x;
}
if (y !== null) {
y = this._bounce(y);
} else {
y = this._y;
}
duration = duration || this._snapToEdge ? Flick.SNAP_DURATION : 0;
easing = easing || this._snapToEdge ? Flick.SNAP_EASING : Flick.EASING;
this._x = x;
this._y = y;
this._anim(x, y, duration, easing);
},
/**
* Internal utility method to perform the transition step
*
* @method _anim
* @param {Number} x The X offset position
* @param {Number} y The Y offset position
* @param {Number} duration The duration to use for the transition animation
* @param {String} easing The easing to use for the transition animation.
*
* @private
*/
_anim : function(x, y, duration, easing) {
var xn = x * -1,
yn = y * -1,
transition = {
duration : duration / 1000,
easing : easing
};
Y.log("Transition: duration, easing:" + transition.duration, transition.easing, "node-flick");
if (Y.Transition.useNative) {
transition.transform = 'translate('+ (xn) + 'px,' + (yn) +'px)';
} else {
transition.left = xn + 'px';
transition.top = yn + 'px';
}
this._node.transition(transition);
},
/**
* Internal utility method to constrain the offset value
* based on the bounce criteria.
*
* @method _bounce
* @param {Number} x The offset value to constrain.
* @param {Number} max The max offset value.
*
* @private
*/
_bounce : function(val, max) {
var bounce = this.get(BOUNCE),
dist = this.get(BOUNCE_DISTANCE),
min = bounce ? -dist : 0;
max = bounce ? max + dist : max;
if(!bounce) {
if(val < min) {
val = min;
} else if(val > max) {
val = max;
}
}
return val;
},
/**
* Stop the animation timer
*
* @method _killTimer
* @private
*/
_killTimer: function() {
if(this._flickTimer) {
this._flickTimer.cancel();
}
}
}, {
/**
* The threshold used to determine when the decelerated velocity of the node
* is practically 0.
*
* @property VELOCITY_THRESHOLD
* @static
* @type Number
* @default 0.015
*/
VELOCITY_THRESHOLD : 0.015,
/**
* The duration to use for the bounce snap-back transition
*
* @property SNAP_DURATION
* @static
* @type Number
* @default 400
*/
SNAP_DURATION : 400,
/**
* The default easing to use for the main flick movement transition
*
* @property EASING
* @static
* @type String
* @default 'cubic-bezier(0, 0.1, 0, 1.0)'
*/
EASING : 'cubic-bezier(0, 0.1, 0, 1.0)',
/**
* The default easing to use for the bounce snap-back transition
*
* @property SNAP_EASING
* @static
* @type String
* @default 'ease-out'
*/
SNAP_EASING : 'ease-out',
/**
* The default CSS class names used by the plugin
*
* @property CLASS_NAMES
* @static
* @type Object
*/
CLASS_NAMES : {
box: getClassName(Flick.NS),
content: getClassName(Flick.NS, "content")
}
});
Y.Plugin.Flick = Flick;
