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@markmarijnissen
Last active August 29, 2015 14:03
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Famo.us: Adds goToFirst, goToLast and goToIndex methods to Scrollview
define(function(require,module,exports){
var Scrollview = require('famous/views/Scrollview');
var ViewSequence = require('famous/core/ViewSequence');
var VELOCITY = 0; // default: No animation (i.e. the item isn't given any "swipe"-velocity when moved)
/***********************************
* getIndex
************************************/
Scrollview.prototype.getIndex = function () {
return this._node.getIndex();
};
/***********************************
* goToIndex
************************************/
Scrollview.prototype.goToIndex = function (i,velocity,position) {
// if we're already there, don't move!
if(i == this.getIndex()) return;
// create ViewSequence node at proper location
var _ = this._node._;
var node = new ViewSequence({
_: _,
index: i
});
// Animate the movement (default is no animation)
if(velocity === undefined) velocity = VELOCITY;
// If animated (i.e. velocity > 0), start at +/- height from the item, and swipe towards proper position (0);
if(position === undefined) position = velocity > 0? this._node.getSize()[this.options.direction]: 0;
// We're swiping from the top, start before (negative height) and swipe down (positive velocity)
position = -1.0 * position;
// Unless we're swiping from the bottom, then we reverse position/velocity;
if(i < this.getIndex()) {
velocity = -1.0 * velocity;
position = -1.0 * position;
}
// Set the Scrollview
this.sequenceFrom(node);
// Position a little bit away from the element
this.setPosition(position);
// And swipe from there -- (and hope that scrollview ends in the right position - it's a bit of guesswork...)
this.setVelocity(velocity);
};
/***********************************
* goToFirst
************************************/
Scrollview.prototype.goToFirst = function (velocity,position) {
this.goToIndex(this._node._.firstIndex,velocity,position);
};
/***********************************
* goToLast
************************************/
Scrollview.prototype.goToLast = function (velocity,position) {
var _ = this._node._;
var index = _.firstIndex + _.array.length - 1;
this.goToIndex(index,position,velocity);
};
});
@kof
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kof commented Jul 14, 2014

Also I suggest to write a constructor like "ScrollviewController" and put all the methods there.

This allows to use your methods together with other classes which subclass Scrollview, f.e. InfiniteScroll

function ScrollviewController(scrollview) {
    this._scrollview = scrollview
}

module.exports = ScrollviewController

ScrollviewController.prototype.getIndex = function () {
  return this._scrollview._node.getIndex()
}

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