quantitativescale.as

用于flash/flex的 as3的 2D图形图像图表的动态生成

package flare.scale
{
	import flare.util.Maths;
	import flare.util.Strings;
	
	/**
	 * Base class for representing quantitative numerical data scales.
	 */
	public class QuantitativeScale extends Scale
	{
		/** The minimum data value. */
		protected var _dmin:Number;
		/** The maximum data value. */
		protected var _dmax:Number;
		/** The minimum value of the scale range. */
		protected var _smin:Number;
		/** The maximum value of the scale range. */
		protected var _smax:Number;
		/** The number base of the scale. */
		protected var _base:Number;

		/**
		 * Creates a new QuantitativeScale.
		 * @param min the minimum data value
		 * @param max the maximum data value
		 * @param base the number base to use
		 * @param flush the flush flag for scale padding
		 * @param labelFormat the formatting pattern for value labels
		 */
		public function QuantitativeScale(min:Number=0, max:Number=0, base:Number=10,
			flush:Boolean=false, labelFormat:String=Strings.DEFAULT_NUMBER)
		{
			this.base = base;
			this.dataMin = min;
			this.dataMax = max;
			this.flush = flush;
			this.labelFormat = labelFormat;
		}

		/** @inheritDoc */
		public override function clone() : Scale
		{
			throw new Error("This is an abstract class");
		}

		// -- Properties ------------------------------------------------------
		
		/** @inheritDoc */
		public override function set flush(val:Boolean):void
		{
			_flush = val; updateScale();
		}
		
		/** @inheritDoc */
		public override function get min():Object { return dataMin; }
		public override function set min(o:Object):void { dataMin = Number(o); }
		
		/** @inheritDoc */
		public override function get max():Object { return dataMax; }
		public override function set max(o:Object):void { dataMax = Number(o); }
		
		/** The minimum data value. This property is the same as the
		 *  <code>minimum</code> property, but properly typed. */
		public function get dataMin():Number
		{
			return _dmin;
		}
		public function set dataMin(val:Number):void
		{
			_dmin = val; updateScale();
		}

		/** The maximum data value. This property is the same as the
		 *  <code>maximum</code> property, but properly typed. */
		public function get dataMax():Number
		{
			return _dmax;
		}
		public function set dataMax(val:Number):void
		{
			_dmax = val; updateScale();
		}
		
		/** The minimum value of the scale range. */
		public function get scaleMin():Number
		{
			return _smin;
		}
		
		/** The maximum value of the scale range. */
		public function get scaleMax():Number
		{
			return _smax;
		}
		
		/** The number base used by the scale.
		 *  By default, base 10 numbers are assumed. */
		public function get base():Number
		{
			return _base;
		}
		public function set base(val:Number):void
		{
			_base = val;
		}
		
		// -- Scale Methods ---------------------------------------------------

		/**
		 * Updates the scale range after a change to the data range.
		 */
		protected function updateScale():void
		{
			if (!_flush) {
                var step:Number = getStep(_dmin, _dmax);
                _smin = Math.floor(_dmin / step) * step;
                _smax = Math.ceil(_dmax / step) * step;
            } else {
                _smin = _dmin;
                _smax = _dmax;
            }
		}

		/**
		 * Returns the default step value between label values. The step is
		 * computed according to the current number base.
		 * @param min the minimum scale value
		 * @param max the maximum scale value
		 * @return the default step value between label values
		 */
		protected function getStep(min:Number, max:Number):Number
		{
			var range:Number = max - min;
			var exp:Number = Math.round(Maths.log(range, _base)) - 1;
			return Math.pow(base, exp);
		}
		
		/** @inheritDoc */
		public override function lookup(f:Number):Object
		{
			return null;
		}
		
		/** @inheritDoc */
		public override function interpolate(value:Object):Number
		{
			return interp(Number(value));
		}

		/**
		 * Returns the interpolation fraction for the given input number.
		 * @param val the input number
		 * @return the interpolation fraction for the input value
		 */
		protected function interp(val:Number):Number
		{
			return -1;
		}
		
		/** @inheritDoc */
		public override function values(num:int=-1):/*Number*/Array
		{
			var a:Array = new Array();
			var range:Number = _smax - _smin;

			if (range == 0) {
				a.push(_smin);
			} else {
				var step:Number = getStep(_smin, _smax);
				var stride:Number = num<0 ? 1 : Math.max(1, Math.floor(range/(step*num)));
				for (var x:Number = _smin; x <= _smax; x += stride*step) {
					a.push(x);
				}
			}
			return a;
		}

	} // end of class QuantitativeScale
}