使用滤镜将一个可视对象的亮度变暗-

/**

* ColorMatrix by Grant Skinner. August 8, 2005

* Updated to AS3 November 19, 2007

* Visit www.gskinner.com/blog for documentation, updates and more free code.

*

* You may distribute this class freely, provided it is not modified in any way (including

* removing this header or changing the package path).

*

* Please contact [email protected] prior to distributing modified versions of this class.



*usage:http://www.gskinner.com/blog/archives/2005/09/flash_8_source.html



*var cm = new ColorMatrix();

* cm.adjustColor(20,20,20,20);

*displayObject.filters = [new ColorMatrixFilter(cm)];

*/



package com.gskinner.geom

{



    dynamic public class ColorMatrix extends Array

    {



// constant for contrast calculations:

        private static const DELTA_INDEX:Array = [

            0,    0.01, 0.02, 0.04, 0.05, 0.06, 0.07, 0.08, 0.1, 0.11,

            0.12, 0.14, 0.15, 0.16, 0.17, 0.18, 0.20, 0.21, 0.22, 0.24,

            0.25, 0.27, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, 0.40, 0.42,

            0.44, 0.46, 0.48, 0.5, 0.53, 0.56, 0.59, 0.62, 0.65, 0.68, 

            0.71, 0.74, 0.77, 0.80, 0.83, 0.86, 0.89, 0.92, 0.95, 0.98,

            1.0, 1.06, 1.12, 1.18, 1.24, 1.30, 1.36, 1.42, 1.48, 1.54,

            1.60, 1.66, 1.72, 1.78, 1.84, 1.90, 1.96, 2.0, 2.12, 2.25, 

            2.37, 2.50, 2.62, 2.75, 2.87, 3.0, 3.2, 3.4, 3.6, 3.8,

            4.0, 4.3, 4.7, 4.9, 5.0, 5.5, 6.0, 6.5, 6.8, 7.0,

            7.3, 7.5, 7.8, 8.0, 8.4, 8.7, 9.0, 9.4, 9.6, 9.8, 

            10.0

           ];



        // identity matrix constant:

        private static const IDENTITY_MATRIX:Array = [

            1,0,0,0,0,

            0,1,0,0,0,

            0,0,1,0,0,

            0,0,0,1,0,

            0,0,0,0,1

           ];

        private static const LENGTH:Number = IDENTITY_MATRIX.length;





// initialization:

        public function ColorMatrix(p_matrix:Array = null)

        {

            p_matrix = fixMatrix(p_matrix);

            copyMatrix(((p_matrix.length == LENGTH) ? p_matrix : IDENTITY_MATRIX));

        }





// public methods:

        public function reset():void

        {

            for (var i:uint = 0; i < LENGTH; i++)

            {

                this[i] = IDENTITY_MATRIX[i];

            }

        }



        public function adjustColor(p_brightness:Number, p_contrast:Number, p_saturation:Number, p_hue:Number):void

        {

            adjustHue(p_hue);

            adjustContrast(p_contrast);

            adjustBrightness(p_brightness);

            adjustSaturation(p_saturation);

        }



        public function adjustBrightness(p_val:Number):void   {

            p_val = cleanValue(p_val, 100);

            if (p_val == 0 || isNaN(p_val))

            {

                return;

            }

             multiplyMatrix([

                 1,0,0,0,p_val,

                 0,1,0,0,p_val,

                 0,0,1,0,p_val,

                 0,0,0,1,0,

                 0,0,0,0,1

                ]);

        }



        public function adjustContrast(p_val:Number):void

        {

            p_val = cleanValue(p_val, 100);

            if (p_val == 0 || isNaN(p_val))

            {

                return;

            }

            var x:Number;

            if (p_val < 0)

            {

                x = 127 + p_val / 100 * 127

            }

            else

            {

                x = p_val % 1;

                if (x == 0)

                {

                    x = DELTA_INDEX[p_val];

                }

                else

                {

                    //x = DELTA_INDEX[(p_val<<0)]; // this is how the IDE does it.

                    x = DELTA_INDEX[(p_val << 0)] * (1 - x) + DELTA_INDEX[(p_val << 0) + 1] * x; // use linear interpolation for more granularity.

                }

                x = x * 127 + 127;

            }

            multiplyMatrix([

                 x/127,0,0,0,0.5*(127-x),

                 0,x/127,0,0,0.5*(127-x),

                 0,0,x/127,0,0.5*(127-x),

                 0,0,0,1,0,

                 0,0,0,0,1

                ]);



        }



        public function adjustSaturation(p_val:Number):void

        {

            p_val = cleanValue(p_val, 100);

            if (p_val == 0 || isNaN(p_val))

            {

                return;

            }

            var x:Number = 1 + ((p_val > 0) ? 3 * p_val / 100 : p_val / 100);

            var lumR:Number = 0.3086;

            var lumG:Number = 0.6094;

            var lumB:Number = 0.0820;

            multiplyMatrix([

                 lumR*(1-x)+x,lumG*(1-x),lumB*(1-x),0,0,

                 lumR*(1-x),lumG*(1-x)+x,lumB*(1-x),0,0,

                 lumR*(1-x),lumG*(1-x),lumB*(1-x)+x,0,0,

                 0,0,0,1,0,

                 0,0,0,0,1

                ]);



        }



        public function adjustHue(p_val:Number):void

        {

            p_val = cleanValue(p_val, 180) / 180 * Math.PI;

            if (p_val == 0 || isNaN(p_val))

            {

                return;

            }

            var cosVal:Number = Math.cos(p_val);

            var sinVal:Number = Math.sin(p_val);

            var lumR:Number = 0.213;

            var lumG:Number = 0.715;

            var lumB:Number = 0.072;

            multiplyMatrix([

                 lumR+cosVal*(1-lumR)+sinVal*(-lumR),lumG+cosVal*(-lumG)+sinVal*(-lumG),lumB+cosVal*(-lumB)+sinVal*(1-lumB),0,0,

                 lumR+cosVal*(-lumR)+sinVal*(0.143),lumG+cosVal*(1-lumG)+sinVal*(0.140),lumB+cosVal*(-lumB)+sinVal*(-0.283),0,0,

                 lumR+cosVal*(-lumR)+sinVal*(-(1-lumR)),lumG+cosVal*(-lumG)+sinVal*(lumG),lumB+cosVal*(1-lumB)+sinVal*(lumB),0,0,

                 0,0,0,1,0,

                 0,0,0,0,1

                ]);



        }



        public function concat(p_matrix:Array):void

        {

            p_matrix = fixMatrix(p_matrix);

            if (p_matrix.length != LENGTH)

            {

                return;

            }

            multiplyMatrix(p_matrix);

        }



        public function clone():ColorMatrix

        {

            return new ColorMatrix(this);

        }



        public function toString():String

        {

            return "ColorMatrix [ " + this.join(" , ") + " ]";

        }



        // return a length 20 array (5x4):

        public function toArray():Array

        {

            return slice(0, 20);

        }



// private methods:

        // copy the specified matrix's values to this matrix:

        protected function copyMatrix(p_matrix:Array):void

        {

            var l:Number = LENGTH;

            for (var i:uint = 0; i < l; i++)

            {

                this[i] = p_matrix[i];

            }

        }



        // multiplies one matrix against another:

        protected function multiplyMatrix(p_matrix:Array):void

        {

            var col:Array = [];



            for (var i:uint = 0; i < 5; i++)

            {

                for (var j:uint = 0; j < 5; j++)

                {

                    col[j] = this[j + i * 5];

                }

                for (j = 0; j < 5; j++)

                {

                    var val:Number = 0;

                    for (var k:Number = 0; k < 5; k++)

                    {

                        val += p_matrix[j + k * 5] * col[k];

                    }

                    this[j + i * 5] = val;

                }

            }

        }



        // make sure values are within the specified range, hue has a limit of 180, others are 100:

        protected function cleanValue(p_val:Number, p_limit:Number):Number

        {

            return Math.min(p_limit, Math.max(-p_limit, p_val));

        }



        // makes sure matrixes are 5x5 (25 long):

        protected function fixMatrix(p_matrix:Array = null):Array

        {

            if (p_matrix == null)

            {

                return IDENTITY_MATRIX;

            }

            if (p_matrix is ColorMatrix)

            {

                p_matrix = p_matrix.slice(0);

            }

            if (p_matrix.length < LENGTH)

            {

                p_matrix = p_matrix.slice(0, p_matrix.length).concat(IDENTITY_MATRIX.slice(p_matrix.length, LENGTH));

            }

            else if (p_matrix.length > LENGTH)

            {

                p_matrix = p_matrix.slice(0, LENGTH);

            }

            return p_matrix;

        }

    }

}

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