iscroll/src/keys/keys.js

Smooth scrolling for the web

	_initKeys: function (e) {
		// default key bindings
		var keys = {
			pageUp: 33,
			pageDown: 34,
			end: 35,
			home: 36,
			left: 37,
			up: 38,
			right: 39,
			down: 40
		};
		var i;

		// if you give me characters I give you keycode
		if ( typeof this.options.keyBindings == 'object' ) {
			for ( i in this.options.keyBindings ) {
				if ( typeof this.options.keyBindings[i] == 'string' ) {
					this.options.keyBindings[i] = this.options.keyBindings[i].toUpperCase().charCodeAt(0);
				}
			}
		} else {
			this.options.keyBindings = {};
		}

		for ( i in keys ) {
			this.options.keyBindings[i] = this.options.keyBindings[i] || keys[i];
		}

		utils.addEvent(window, 'keydown', this);

		this.on('destroy', function () {
			utils.removeEvent(window, 'keydown', this);
		});
	},

	_key: function (e) {
		if ( !this.enabled ) {
			return;
		}

		var snap = this.options.snap,	// we are using this alot, better to cache it
			newX = snap ? this.currentPage.pageX : this.x,
			newY = snap ? this.currentPage.pageY : this.y,
			now = utils.getTime(),
			prevTime = this.keyTime || 0,
			acceleration = 0.250,
			pos;

		if ( this.options.useTransition && this.isInTransition ) {
			pos = this.getComputedPosition();

			this._translate(Math.round(pos.x), Math.round(pos.y));
			this.isInTransition = false;
		}

		this.keyAcceleration = now - prevTime < 200 ? Math.min(this.keyAcceleration + acceleration, 50) : 0;

		switch ( e.keyCode ) {
			case this.options.keyBindings.pageUp:
				if ( this.hasHorizontalScroll && !this.hasVerticalScroll ) {
					newX += snap ? 1 : this.wrapperWidth;
				} else {
					newY += snap ? 1 : this.wrapperHeight;
				}
				break;
			case this.options.keyBindings.pageDown:
				if ( this.hasHorizontalScroll && !this.hasVerticalScroll ) {
					newX -= snap ? 1 : this.wrapperWidth;
				} else {
					newY -= snap ? 1 : this.wrapperHeight;
				}
				break;
			case this.options.keyBindings.end:
				newX = snap ? this.pages.length-1 : this.maxScrollX;
				newY = snap ? this.pages[0].length-1 : this.maxScrollY;
				break;
			case this.options.keyBindings.home:
				newX = 0;
				newY = 0;
				break;
			case this.options.keyBindings.left:
				newX += snap ? -1 : 5 + this.keyAcceleration>>0;
				break;
			case this.options.keyBindings.up:
				newY += snap ? 1 : 5 + this.keyAcceleration>>0;
				break;
			case this.options.keyBindings.right:
				newX -= snap ? -1 : 5 + this.keyAcceleration>>0;
				break;
			case this.options.keyBindings.down:
				newY -= snap ? 1 : 5 + this.keyAcceleration>>0;
				break;
			default:
				return;
		}

		if ( snap ) {
			this.goToPage(newX, newY);
			return;
		}

		if ( newX > 0 ) {
			newX = 0;
			this.keyAcceleration = 0;
		} else if ( newX < this.maxScrollX ) {
			newX = this.maxScrollX;
			this.keyAcceleration = 0;
		}

		if ( newY > 0 ) {
			newY = 0;
			this.keyAcceleration = 0;
		} else if ( newY < this.maxScrollY ) {
			newY = this.maxScrollY;
			this.keyAcceleration = 0;
		}

		this.scrollTo(newX, newY, 0);

		this.keyTime = now;
	},