| /* | |
| * ColourGradient.js | |
| * | |
| * | |
| * Copyright (c) 2011 Greg Ross | |
| * All rights reserved. | |
| * | |
| * Redistribution and use in source and binary forms, with or without | |
| * modification, are permitted provided that the following conditions | |
| * are met: | |
| * | |
| * Redistributions of source code must retain the above copyright notice, | |
| * this list of conditions and the following disclaimer. | |
| * | |
| * Redistributions in binary form must reproduce the above copyright | |
| * notice, this list of conditions and the following disclaimer in the | |
| * documentation and/or other materials provided with the distribution. | |
| * | |
| * Neither the name of the project's author nor the names of its | |
| * contributors may be used to endorse or promote products derived from | |
| * this software without specific prior written permission. | |
| * | |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED | |
| * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |
| * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING | |
| * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | |
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| * | |
| */ | |
| /** | |
| * Class that is used to define a path through RGB space. | |
| * @author Greg Ross | |
| * @constructor | |
| * @param minValue the value that will return the first colour on the path in RGB space | |
| * @param maxValue the value that will return the last colour on the path in RGB space | |
| * @param rgbColourArray the set of colours that defines the dirctional path through RGB space. | |
| * The length of the array must be greater than two. | |
| */ | |
| ColourGradient = function(minValue, maxValue, rgbColourArray) | |
| { | |
| function RGB2HTML(red, green, blue) | |
| { | |
| var decColor = red + 256 * green + 65536 * blue; | |
| return decColor.toString(16); | |
| } | |
| /** | |
| * Return a colour from a position on the path in RGB space that is proportioal to | |
| * the number specified in relation to the minimum and maximum values from which the | |
| * bounds of the path are derived. | |
| * @member greg.ross.visualisation.ColourGradient | |
| * @param value | |
| */ | |
| this.getColour = function(value) | |
| { | |
| if (value < minValue || value > maxValue || rgbColourArray.length == 1) | |
| { | |
| var colr = { | |
| red: rgbColourArray[0].red, | |
| green:rgbColourArray[0].green, | |
| blue:rgbColourArray[0].blue | |
| }; | |
| return colr; | |
| } | |
| var scaledValue = mapValueToZeroOneInterval(value, minValue, maxValue); | |
| return getPointOnColourRamp(scaledValue); | |
| } | |
| function getPointOnColourRamp(value) | |
| { | |
| if (value+""=="NaN") { | |
| value=0; | |
| } | |
| var numberOfColours = rgbColourArray.length; | |
| var scaleWidth = 1 / (numberOfColours - 1); | |
| var index = (value / scaleWidth); | |
| var index = parseInt(index + ""); | |
| index = index == (numberOfColours - 1) ? index - 1 : index; | |
| var rgb1 = rgbColourArray[index]; | |
| var rgb2 = rgbColourArray[index + 1]; | |
| var closestToOrigin, furthestFromOrigin; | |
| if (distanceFromRgbOrigin(rgb1) > distanceFromRgbOrigin(rgb2)) | |
| { | |
| closestToOrigin = rgb2; | |
| furthestFromOrigin = rgb1; | |
| } | |
| else | |
| { | |
| closestToOrigin = rgb1; | |
| furthestFromOrigin = rgb2; | |
| } | |
| var t; | |
| if (closestToOrigin == rgb2) | |
| t = 1 - mapValueToZeroOneInterval(value, index * scaleWidth, (index + 1) * scaleWidth); | |
| else | |
| t = mapValueToZeroOneInterval(value, index * scaleWidth, (index + 1) * scaleWidth); | |
| var diff = [ | |
| t * (furthestFromOrigin.red - closestToOrigin.red), | |
| t * (furthestFromOrigin.green - closestToOrigin.green), | |
| t * (furthestFromOrigin.blue - closestToOrigin.blue)]; | |
| var r = closestToOrigin.red + diff[0]; | |
| var g = closestToOrigin.green + diff[1]; | |
| var b = closestToOrigin.blue + diff[2]; | |
| r = parseInt(r); | |
| g = parseInt(g); | |
| b = parseInt(b); | |
| var colr = { | |
| red:r, | |
| green:g, | |
| blue:b | |
| }; | |
| return colr; | |
| } | |
| function distanceFromRgbOrigin(rgb) | |
| { | |
| return (rgb.red * rgb.red) + (rgb.green * rgb.green) + (rgb.blue * rgb.blue); | |
| } | |
| function mapValueToZeroOneInterval(value, minValue, maxValue) | |
| { | |
| if (minValue == maxValue) return 0; | |
| var factor = (value - minValue) / (maxValue - minValue); | |
| return factor; | |
| } | |
| } | |