instiki/public/svg-edit/editor/math.js
2011-06-01 15:28:11 -05:00

246 lines
7.3 KiB
JavaScript

/**
* Package: svedit.math
*
* Licensed under the Apache License, Version 2
*
* Copyright(c) 2010 Alexis Deveria
* Copyright(c) 2010 Jeff Schiller
*/
// Dependencies:
// None.
var svgedit = svgedit || {};
(function() {
if (!svgedit.math) {
svgedit.math = {};
}
// Constants
var NEAR_ZERO = 1e-14;
// Throw away SVGSVGElement used for creating matrices/transforms.
var svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
// Function: svgedit.math.transformPoint
// A (hopefully) quicker function to transform a point by a matrix
// (this function avoids any DOM calls and just does the math)
//
// Parameters:
// x - Float representing the x coordinate
// y - Float representing the y coordinate
// m - Matrix object to transform the point with
// Returns a x,y object representing the transformed point
svgedit.math.transformPoint = function(x, y, m) {
return { x: m.a * x + m.c * y + m.e, y: m.b * x + m.d * y + m.f};
};
// Function: svgedit.math.isIdentity
// Helper function to check if the matrix performs no actual transform
// (i.e. exists for identity purposes)
//
// Parameters:
// m - The matrix object to check
//
// Returns:
// Boolean indicating whether or not the matrix is 1,0,0,1,0,0
svgedit.math.isIdentity = function(m) {
return (m.a === 1 && m.b === 0 && m.c === 0 && m.d === 1 && m.e === 0 && m.f === 0);
};
// Function: svgedit.math.matrixMultiply
// This function tries to return a SVGMatrix that is the multiplication m1*m2.
// We also round to zero when it's near zero
//
// Parameters:
// >= 2 Matrix objects to multiply
//
// Returns:
// The matrix object resulting from the calculation
svgedit.math.matrixMultiply = function() {
var args = arguments, i = args.length, m = args[i-1];
while(i-- > 1) {
var m1 = args[i-1];
m = m1.multiply(m);
}
if (Math.abs(m.a) < NEAR_ZERO) m.a = 0;
if (Math.abs(m.b) < NEAR_ZERO) m.b = 0;
if (Math.abs(m.c) < NEAR_ZERO) m.c = 0;
if (Math.abs(m.d) < NEAR_ZERO) m.d = 0;
if (Math.abs(m.e) < NEAR_ZERO) m.e = 0;
if (Math.abs(m.f) < NEAR_ZERO) m.f = 0;
return m;
};
// Function: svgedit.math.hasMatrixTransform
// See if the given transformlist includes a non-indentity matrix transform
//
// Parameters:
// tlist - The transformlist to check
//
// Returns:
// Boolean on whether or not a matrix transform was found
svgedit.math.hasMatrixTransform = function(tlist) {
if(!tlist) return false;
var num = tlist.numberOfItems;
while (num--) {
var xform = tlist.getItem(num);
if (xform.type == 1 && !svgedit.math.isIdentity(xform.matrix)) return true;
}
return false;
};
// Function: svgedit.math.transformBox
// Transforms a rectangle based on the given matrix
//
// Parameters:
// l - Float with the box's left coordinate
// t - Float with the box's top coordinate
// w - Float with the box width
// h - Float with the box height
// m - Matrix object to transform the box by
//
// Returns:
// An object with the following values:
// * tl - The top left coordinate (x,y object)
// * tr - The top right coordinate (x,y object)
// * bl - The bottom left coordinate (x,y object)
// * br - The bottom right coordinate (x,y object)
// * aabox - Object with the following values:
// * Float with the axis-aligned x coordinate
// * Float with the axis-aligned y coordinate
// * Float with the axis-aligned width coordinate
// * Float with the axis-aligned height coordinate
svgedit.math.transformBox = function(l, t, w, h, m) {
var topleft = {x:l,y:t},
topright = {x:(l+w),y:t},
botright = {x:(l+w),y:(t+h)},
botleft = {x:l,y:(t+h)};
var transformPoint = svgedit.math.transformPoint;
topleft = transformPoint( topleft.x, topleft.y, m );
var minx = topleft.x,
maxx = topleft.x,
miny = topleft.y,
maxy = topleft.y;
topright = transformPoint( topright.x, topright.y, m );
minx = Math.min(minx, topright.x);
maxx = Math.max(maxx, topright.x);
miny = Math.min(miny, topright.y);
maxy = Math.max(maxy, topright.y);
botleft = transformPoint( botleft.x, botleft.y, m);
minx = Math.min(minx, botleft.x);
maxx = Math.max(maxx, botleft.x);
miny = Math.min(miny, botleft.y);
maxy = Math.max(maxy, botleft.y);
botright = transformPoint( botright.x, botright.y, m );
minx = Math.min(minx, botright.x);
maxx = Math.max(maxx, botright.x);
miny = Math.min(miny, botright.y);
maxy = Math.max(maxy, botright.y);
return {tl:topleft, tr:topright, bl:botleft, br:botright,
aabox: {x:minx, y:miny, width:(maxx-minx), height:(maxy-miny)} };
};
// Function: svgedit.math.transformListToTransform
// This returns a single matrix Transform for a given Transform List
// (this is the equivalent of SVGTransformList.consolidate() but unlike
// that method, this one does not modify the actual SVGTransformList)
// This function is very liberal with its min,max arguments
//
// Parameters:
// tlist - The transformlist object
// min - Optional integer indicating start transform position
// max - Optional integer indicating end transform position
//
// Returns:
// A single matrix transform object
svgedit.math.transformListToTransform = function(tlist, min, max) {
if(tlist == null) {
// Or should tlist = null have been prevented before this?
return svg.createSVGTransformFromMatrix(svg.createSVGMatrix());
}
var min = min == undefined ? 0 : min;
var max = max == undefined ? (tlist.numberOfItems-1) : max;
min = parseInt(min);
max = parseInt(max);
if (min > max) { var temp = max; max = min; min = temp; }
var m = svg.createSVGMatrix();
for (var i = min; i <= max; ++i) {
// if our indices are out of range, just use a harmless identity matrix
var mtom = (i >= 0 && i < tlist.numberOfItems ?
tlist.getItem(i).matrix :
svg.createSVGMatrix());
m = svgedit.math.matrixMultiply(m, mtom);
}
return svg.createSVGTransformFromMatrix(m);
};
// Function: svgedit.math.getMatrix
// Get the matrix object for a given element
//
// Parameters:
// elem - The DOM element to check
//
// Returns:
// The matrix object associated with the element's transformlist
svgedit.math.getMatrix = function(elem) {
var tlist = svgedit.transformlist.getTransformList(elem);
return svgedit.math.transformListToTransform(tlist).matrix;
};
// Function: svgedit.math.snapToAngle
// Returns a 45 degree angle coordinate associated with the two given
// coordinates
//
// Parameters:
// x1 - First coordinate's x value
// x2 - Second coordinate's x value
// y1 - First coordinate's y value
// y2 - Second coordinate's y value
//
// Returns:
// Object with the following values:
// x - The angle-snapped x value
// y - The angle-snapped y value
// snapangle - The angle at which to snap
svgedit.math.snapToAngle = function(x1,y1,x2,y2) {
var snap = Math.PI/4; // 45 degrees
var dx = x2 - x1;
var dy = y2 - y1;
var angle = Math.atan2(dy,dx);
var dist = Math.sqrt(dx * dx + dy * dy);
var snapangle= Math.round(angle/snap)*snap;
var x = x1 + dist*Math.cos(snapangle);
var y = y1 + dist*Math.sin(snapangle);
//console.log(x1,y1,x2,y2,x,y,angle)
return {x:x, y:y, a:snapangle};
};
// Function: rectsIntersect
// Check if two rectangles (BBoxes objects) intersect each other
//
// Paramaters:
// r1 - The first BBox-like object
// r2 - The second BBox-like object
//
// Returns:
// Boolean that's true if rectangles intersect
svgedit.math.rectsIntersect = function(r1, r2) {
return r2.x < (r1.x+r1.width) &&
(r2.x+r2.width) > r1.x &&
r2.y < (r1.y+r1.height) &&
(r2.y+r2.height) > r1.y;
};
})();