helper_functions.js

《SVG开发实践》源代码

/**
 * @fileoverview
 * 
 * ECMAScript <a href="http://www.carto.net/papers/svg/resources/helper_functions.html">helper functions</a>, main purpose is to serve in SVG mapping or other SVG based web applications
 *
 * This ECMA script library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library (http://www.carto.net/papers/svg/resources/lesser_gpl.txt); if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Please report bugs and send improvements to [e-mail]
 * If you use these scripts, please link to the original (http://www.carto.net/papers/svg/resources/helper_functions.html)
 * somewhere in the source-code-comment or the "about" of your project and give credits, thanks!
 * 
 * See <a href="js_docs_out/overview-summary-helper_functions.js.html">documentation</a>. 
 * 
 * @author Andreas Neumann [e-mail]
 * @copyright LGPL 2.1 <a href="http://www.gnu.org/copyleft/lesser.txt">Gnu LGPL 2.1</a>
 * @credits Bruce Rindahl, numerous people on [e-mail]
 */

//global variables necessary to create elements in these namespaces, do not delete them!!!!

/**
 * This variable is a shortcut to the full URL of the SVG namespace
 * @final
 * @type String
 */
var svgNS = "http://www.w3.org/2000/svg";

/**
 * This variable is a shortcut to the full URL of the XLink namespace
 * @final
 * @type String
 */
var xlinkNS = "http://www.w3.org/1999/xlink";

/**
 * This variable is a shortcut to the full URL of the attrib namespace
 * @final
 * @type String
 */
var cartoNS = "http://www.carto.net/attrib";

/**
 * This variable is a alias to the full URL of the attrib namespace
 * @final
 * @type String
 */
var attribNS = "http://www.carto.net/attrib";

/**
 * This variable is a alias to the full URL of the Batik extension namespace
 * @final
 * @type String
 */
var batikNS = "http://xml.apache.org/batik/ext";

/**
 * Returns the polar direction from a given vector
 * @param {Number} xdiff	the x-part of the vector
 * @param {Number} ydiff	the y-part of the vector
 * @return direction		the direction in radians
 * @type Number
 * @version 1.0 (2007-04-30)
 * @see #toPolarDist
 * @see #toRectX
 * @see #toRectY
 */
function toPolarDir(xdiff,ydiff) {
   var direction = (Math.atan2(ydiff,xdiff));
   return(direction);
}

/**
 * Returns the polar distance from a given vector
 * @param {Number} xdiff	the x-part of the vector
 * @param {Number} ydiff	the y-part of the vector
 * @return distance			the distance
 * @type Number
 * @version 1.0 (2007-04-30)
 * @see #toPolarDir
 * @see #toRectX
 * @see #toRectY
 */
function toPolarDist(xdiff,ydiff) {
   var distance = Math.sqrt(xdiff * xdiff + ydiff * ydiff);
   return(distance);
}

/**
 * Returns the x-part of a vector from a given direction and distance
 * @param {Number} direction	the direction (in radians)
 * @param {Number} distance		the distance
 * @return x					the x-part of the vector
 * @type Number
 * @version 1.0 (2007-04-30)
 * @see #toPolarDist
 * @see #toPolarDir
 * @see #toRectY
 */
function toRectX(direction,distance) {
   var x = distance * Math.cos(direction);
   return(x);
}

/**
 * Returns the y-part of the vector from a given direction and distance
 * @param {Number} direction	the direction (in radians)
 * @param {Number} distance		the distance
 * @return y					the y-part of the vector
 * @type Number
 * @version 1.0 (2007-04-30)
 * @see #toPolarDist
 * @see #toPolarDir
 * @see #toRectX
 */
function toRectY(direction,distance) {
   y = distance * Math.sin(direction);
   return(y);
}

/**
 * Converts degrees to radians
 * @param {Number} deg	the degree value
 * @return rad			the radians value
 * @type Number
 * @version 1.0 (2007-04-30)
 * @see #RadToDeg
 */
function DegToRad(deg) {
     return (deg / 180.0 * Math.PI);
}

/**
 * Converts radians to degrees
 * @param {Number} rad	the radians value
 * @return deg			the degree value
 * @type Number
 * @version 1.0 (2007-04-30)
 * @see #DegToRad
 */
function RadToDeg(rad) {
     return (rad / Math.PI * 180.0);
}

/**
 * Converts decimal degrees to degrees, minutes, seconds
 * @param {Number} dd	the decimal degree value
 * @return degrees		the degree values in the following notation: {deg:degrees,min:minutes,sec:seconds}
 * @type literal
 * @version 1.0 (2007-04-30)
 * @see #dms2dd
 */
function dd2dms(dd) {
        var minutes = (Math.abs(dd) - Math.floor(Math.abs(dd))) * 60;
        var seconds = (minutes - Math.floor(minutes)) * 60;
        var minutes = Math.floor(minutes);
        if (dd >= 0) {
            var degrees = Math.floor(dd);
        }
        else {
            var degrees = Math.ceil(dd);       
        }
        return {deg:degrees,min:minutes,sec:seconds};
}

/**
 * Converts degrees, minutes and seconds to decimal degrees
 * @param {Number} deg	the degree value
 * @param {Number} min	the minute value
 * @param {Number} sec	the second value
 * @return deg			the decimal degree values
 * @type Number
 * @version 1.0 (2007-04-30)
 * @see #dd2dms
 */
function dms2dd(deg,min,sec) {
	if (deg < 0) {
		return deg - (min / 60) - (sec / 3600);
	}
	else {
		return deg + (min / 60) + (sec / 3600);
	}
}

/**
 * log function, missing in the standard Math object
 * @param {Number} x	the value where the log function should be applied to
 * @param {Number} b	the base value for the log function
 * @return logResult	the result of the log function
 * @type Number
 * @version 1.0 (2007-04-30)
 */
function log(x,b) {
	if(b==null) b=Math.E;
	return Math.log(x)/Math.log(b);
}

/**
 * interpolates a value (e.g. elevation) bilinearly based on the position within a cell with 4 corner values
 * @param {Number} za		the value at the upper left corner of the cell
 * @param {Number} zb		the value at the upper right corner of the cell
 * @param {Number} zc		the value at the lower right corner of the cell
 * @param {Number} zd		the value at the lower left corner of the cell
 * @param {Number} xpos		the x position of the point where a new value should be interpolated
 * @param {Number} ypos		the y position of the point where a new value should be interpolated
 * @param {Number} ax		the x position of the lower left corner of the cell
 * @param {Number} ay		the y position of the lower left corner of the cell
 * @param {Number} cellsize	the size of the cell
 * @return interpol_value	the result of the bilinear interpolation function
 * @type Number
 * @version 1.0 (2007-04-30)
 */
function intBilinear(za,zb,zc,zd,xpos,ypos,ax,ay,cellsize) { //bilinear interpolation function
	var e = (xpos - ax) / cellsize;
	var f = (ypos - ay) / cellsize;

	//calculation of weights
	var wa = (1 - e) * (1 - f);
	var wb = e * (1 - f);
	var wc = e * f;
	var wd = f * (1 - e);

	var interpol_value = wa * zc + wb * zd + wc * za + wd * zb;
	return interpol_value;	
}

/**
 * tests if a given point is left or right of a given line
 * @param {Number} pointx		the x position of the given point
 * @param {Number} pointy		the y position of the given point
 * @param {Number} linex1		the x position of line's start point
 * @param {Number} liney1		the y position of line's start point
 * @param {Number} linex2		the x position of line's end point
 * @param {Number} liney2		the y position of line's end point
 * @return leftof				the result of the leftOfTest, 1 means leftOf, 0 means rightOf
 * @type Number (integer, 0|1)
 * @version 1.0 (2007-04-30)
 */
function leftOfTest(pointx,pointy,linex1,liney1,linex2,liney2) {
	var result = (liney1 - pointy) * (linex2 - linex1) - (linex1 - pointx) * (liney2 - liney1);
	if (result < 0) {
		var leftof = 1; //case left of
	}
	else {
		var leftof = 0; //case left of	
	}
	return leftof;
}

/**
 * calculates the distance between a given point and a given line
 * @param {Number} pointx		the x position of the given point
 * @param {Number} pointy		the y position of the given point
 * @param {Number} linex1		the x position of line's start point
 * @param {Number} liney1		the y position of line's start point
 * @param {Number} linex2		the x position of line's end point
 * @param {Number} liney2		the y position of line's end point
 * @return distance				the result of the leftOfTest, 1 means leftOf, 0 means rightOf
 * @type Number
 * @version 1.0 (2007-04-30)
 */
function distFromLine(xpoint,ypoint,linex1,liney1,linex2,liney2) {
	var dx = linex2 - linex1;
	var dy = liney2 - liney1;
	var distance = (dy * (xpoint - linex1) - dx * (ypoint - liney1)) / Math.sqrt(Math.pow(dx,2) + Math.pow(dy,2));
	return distance;
}

/**
 * calculates the angle between two vectors (lines)
 * @param {Number} ax		the x part of vector a
 * @param {Number} ay		the y part of vector a
 * @param {Number} bx		the x part of vector b
 * @param {Number} by		the y part of vector b
 * @return angle			the angle in radians
 * @type Number
 * @version 1.0 (2007-04-30)
 * @credits <a href="http://www.mathe-online.at/mathint/vect2/i.html#Winkel">Mathe Online (Winkel)</a>
 */
function angleBetwTwoLines(ax,ay,bx,by) {
	var angle = Math.acos((ax * bx + ay * by) / (Math.sqrt(Math.pow(ax,2) + Math.pow(ay,2)) * Math.sqrt(Math.pow(bx,2) + Math.pow(by,2))));
	return angle;
}

/**
 * calculates the bisector vector for two given vectors
 * @param {Number} ax		the x part of vector a
 * @param {Number} ay		the y part of vector a
 * @param {Number} bx		the x part of vector b
 * @param {Number} by		the y part of vector b
 * @return c				the resulting vector as an Array, c[0] is the x part of the vector, c[1] is the y part
 * @type Array
 * @version 1.0 (2007-04-30)
 * @credits <a href="http://www.mathe-online.at/mathint/vect1/i.html#Winkelsymmetrale">Mathe Online (Winkelsymmetrale)</a>
 * see #calcBisectorAngle
 *  */
function calcBisectorVector(ax,ay,bx,by) {
	var betraga = Math.sqrt(Math.pow(ax,2) + Math.pow(ay,2));
	var betragb = Math.sqrt(Math.pow(bx,2) + Math.pow(by,2));
	var c = new Array();
	c[0] = ax / betraga + bx / betragb;
	c[1] = ay / betraga + by / betragb;
	return c;
}

/**
 * calculates the bisector angle for two given vectors
 * @param {Number} ax		the x part of vector a
 * @param {Number} ay		the y part of vector a
 * @param {Number} bx		the x part of vector b
 * @param {Number} by		the y part of vector b
 * @return angle			the bisector angle in radians
 * @type Number
 * @version 1.0 (2007-04-30)
 * @credits <a href="http://www.mathe-online.at/mathint/vect1/i.html#Winkelsymmetrale">Mathe Online (Winkelsymmetrale)</a>
 * see #calcBisectorVector
 * */
function calcBisectorAngle(ax,ay,bx,by) {
	var betraga = Math.sqrt(Math.pow(ax,2) + Math.pow(ay,2));
	var betragb = Math.sqrt(Math.pow(bx,2) + Math.pow(by,2));
	var c1 = ax / betraga + bx / betragb;
	var c2 = ay / betraga + by / betragb;
	var angle = toPolarDir(c1,c2);
	return angle;
}

/**
 * calculates the intersection point of two given lines
 * @param {Number} line1x1	the x the start point of line 1
 * @param {Number} line1y1	the y the start point of line 1
 * @param {Number} line1x2	the x the end point of line 1
 * @param {Number} line1y2	the y the end point of line 1
 * @return interSectPoint	the intersection point, interSectPoint.x contains x-part, interSectPoint.y the y-part of the resulting coordinate
 * @type Object
 * @version 1.0 (2007-04-30)
 * @credits <a href="http://astronomy.swin.edu.au/~pbourke/geometry/lineline2d/">P. Bourke</a>
 */
function intersect2lines(line1x1,line1y1,line1x2,line1y2,line2x1,line2y1,line2x2,line2y2) {
	var interSectPoint = new Object();
	var denominator = (line2y2 - line2y1)*(line1x2 - line1x1) - (line2x2 - line2x1)*(line1y2 - line1y1);
	if (denominator == 0) {
		alert("lines are parallel");
	}
	else {
		var ua = ((line2x2 - line2x1)*(line1y1 - line2y1) - (line2y2 - line2y1)*(line1x1 - line2x1)) / denominator;
		var ub = ((line1x2 - line1x1)*(line1y1 - line2y1) - (line1y2 - line1y1)*(line1x1 - line2x1)) / denominator;
	}
	interSectPoint["x"] = line1x1 + ua * (line1x2 - line1x1);
	interSectPoint["y"] = line1y1 + ua * (line1y2 - line1y1);
	return interSectPoint;
}

/**
 * reformats a given number to a string by adding separators at every third digit
 * @param {String|Number} inputNumber	the input number, can be of type number or string
 * @param {String} separator			the separator, e.g. ' or ,
 * @return newString					the intersection point, interSectPoint.x contains x-part, interSectPoint.y the y-part of the resulting coordinate
 * @type String
 * @version 1.0 (2007-04-30)
 */
function formatNumberString(inputNumber,separator) {
	//check if of type string, if number, convert it to string
	if (typeof(inputNumber) == "Number") {
		var myTempString = inputNumber.toString();
	}
	else {
		var myTempString = inputNumber;
	}
	var newString="";
	//if it contains a comma, it will be split
	var splitResults = myTempString.split(".");
	var myCounter = splitResults[0].length;
	if (myCounter > 3) {
		while(myCounter > 0) {
			if (myCounter > 3) {
				newString = separator + splitResults[0].substr(myCounter - 3,3) + newString;
			}
			else {
				newString = splitResults[0].substr(0,myCounter) + newString;
			}
			myCounter -= 3;
		}
	}
	else {
		newString = splitResults[0];
	}
	//concatenate if it contains a comma
	if (splitResults[1]) {
		newString = newString + "." + splitResults[1];
	}
	return newString;
}

/**
 * writes a status text message out to a SVG text element's first child
 * @param {String} statusText	the text message to be displayed
 * @version 1.0 (2007-04-30)
 */