return dojo.gfx.matrix._multiplyPoint(m, a.x, a.y); // dojo.gfx.Point	},	multiply: function(matrix){		// summary: combines matrices by multiplying them sequentially in the given order		// matrix: dojo.gfx.matrix.Matrix2D...: a 2D matrix-like object, 		//		all subsequent arguments are matrix-like objects too		var m = dojo.gfx.matrix.normalize(matrix);		// combine matrices		for(var i = 1; i < arguments.length; ++i){			var l = m;			var r = dojo.gfx.matrix.normalize(arguments[i]);			m = new dojo.gfx.matrix.Matrix2D();			m.xx = l.xx * r.xx + l.xy * r.yx;			m.xy = l.xx * r.xy + l.xy * r.yy;			m.yx = l.yx * r.xx + l.yy * r.yx;			m.yy = l.yx * r.xy + l.yy * r.yy;			m.dx = l.xx * r.dx + l.xy * r.dy + l.dx;			m.dy = l.yx * r.dx + l.yy * r.dy + l.dy;		}		return m; // dojo.gfx.matrix.Matrix2D	},		// high level operations		_sandwich: function(m, x, y){		// summary: applies a matrix at a centrtal point		// m: dojo.gfx.matrix.Matrix2D: a 2D matrix-like object, which is applied at a central point		// x: Number: an x component of the central point		// y: Number: a y component of the central point		return dojo.gfx.matrix.multiply(dojo.gfx.matrix.translate(x, y), m, dojo.gfx.matrix.translate(-x, -y)); // dojo.gfx.matrix.Matrix2D	},	scaleAt: function(a, b, c, d){		// summary: scales a picture using a specified point as a center of scaling		// description: Compare with dojo.gfx.matrix.scale().		// a: Number: a scaling factor used for the x coordinate		// b: Number: a scaling factor used for the y coordinate		// c: Number: an x component of a central point		// d: Number: a y component of a central point				// accepts several signatures:		//	1) uniform scale factor, Point		//	2) uniform scale factor, x, y		//	3) x scale, y scale, Point		//	4) x scale, y scale, x, y				switch(arguments.length){			case 4:				// a and b are scale factor components, c and d are components of a point				return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.scale(a, b), c, d); // dojo.gfx.matrix.Matrix2D			case 3:				if(typeof c == "number"){					// branch					// a: Number: a uniform scaling factor used for both coordinates					// b: Number: an x component of a central point					// c: Number: a y component of a central point					// d: null					return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.scale(a), b, c); // dojo.gfx.matrix.Matrix2D				}				// branch				// a: Number: a scaling factor used for the x coordinate				// b: Number: a scaling factor used for the y coordinate				// c: dojo.gfx.Point: a central point				// d: null				return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.scale(a, b), c.x, c.y); // dojo.gfx.matrix.Matrix2D		}		// branch		// a: Number: a uniform scaling factor used for both coordinates		// b: dojo.gfx.Point: a central point		// c: null		// d: null		return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.scale(a), b.x, b.y); // dojo.gfx.matrix.Matrix2D	},	rotateAt: function(angle, a, b){		// summary: rotates a picture using a specified point as a center of rotation		// description: Compare with dojo.gfx.matrix.rotate().		// angle: Number: an angle of rotation in radians (>0 for CCW)		// a: Number: an x component of a central point		// b: Number: a y component of a central point				// accepts several signatures:		//	1) rotation angle in radians, Point		//	2) rotation angle in radians, x, y				if(arguments.length > 2){			return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.rotate(angle), a, b); // dojo.gfx.matrix.Matrix2D		}				// branch		// angle: Number: an angle of rotation in radians (>0 for CCW)		// a: dojo.gfx.Point: a central point		// b: null		return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.rotate(angle), a.x, a.y); // dojo.gfx.matrix.Matrix2D	},	rotategAt: function(degree, a, b){		// summary: rotates a picture using a specified point as a center of rotation		// description: Compare with dojo.gfx.matrix.rotateg().		// degree: Number: an angle of rotation in degrees (>0 for CCW)		// a: Number: an x component of a central point		// b: Number: a y component of a central point				// accepts several signatures:		//	1) rotation angle in degrees, Point		//	2) rotation angle in degrees, x, y				if(arguments.length > 2){			return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.rotateg(degree), a, b); // dojo.gfx.matrix.Matrix2D		}		// branch		// degree: Number: an angle of rotation in degrees (>0 for CCW)		// a: dojo.gfx.Point: a central point		// b: null		return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.rotateg(degree), a.x, a.y); // dojo.gfx.matrix.Matrix2D	},	skewXAt: function(angle, a, b){		// summary: skews a picture along the x axis using a specified point as a center of skewing		// description: Compare with dojo.gfx.matrix.skewX().		// angle: Number: an skewing angle in radians		// a: Number: an x component of a central point		// b: Number: a y component of a central point				// accepts several signatures:		//	1) skew angle in radians, Point		//	2) skew angle in radians, x, y				if(arguments.length > 2){			return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.skewX(angle), a, b); // dojo.gfx.matrix.Matrix2D		}		// branch		// angle: Number: an skewing angle in radians		// a: dojo.gfx.Point: a central point		// b: null		return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.skewX(angle), a.x, a.y); // dojo.gfx.matrix.Matrix2D	},	skewXgAt: function(degree, a, b){		// summary: skews a picture along the x axis using a specified point as a center of skewing		// description: Compare with dojo.gfx.matrix.skewXg().		// degree: Number: an skewing angle in degrees		// a: Number: an x component of a central point		// b: Number: a y component of a central point				// accepts several signatures:		//	1) skew angle in degrees, Point		//	2) skew angle in degrees, x, y		if(arguments.length > 2){			return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.skewXg(degree), a, b); // dojo.gfx.matrix.Matrix2D		}		// branch		// degree: Number: an skewing angle in degrees		// a: dojo.gfx.Point: a central point		// b: null		return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.skewXg(degree), a.x, a.y); // dojo.gfx.matrix.Matrix2D	},	skewYAt: function(angle, a, b){		// summary: skews a picture along the y axis using a specified point as a center of skewing		// description: Compare with dojo.gfx.matrix.skewY().		// angle: Number: an skewing angle in radians		// a: Number: an x component of a central point		// b: Number: a y component of a central point				// accepts several signatures:		//	1) skew angle in radians, Point		//	2) skew angle in radians, x, y				if(arguments.length > 2){			return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.skewY(angle), a, b); // dojo.gfx.matrix.Matrix2D		}		// branch		// angle: Number: an skewing angle in radians		// a: dojo.gfx.Point: a central point		// b: null		return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.skewY(angle), a.x, a.y); // dojo.gfx.matrix.Matrix2D	},	skewYgAt: function(/* Number */ degree, /* Number||Point */ a, /* Number, optional */ b){		// summary: skews a picture along the y axis using a specified point as a center of skewing		// description: Compare with dojo.gfx.matrix.skewYg().		// degree: Number: an skewing angle in degrees		// a: Number: an x component of a central point		// b: Number: a y component of a central point				// accepts several signatures:		//	1) skew angle in degrees, Point		//	2) skew angle in degrees, x, y		if(arguments.length > 2){			return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.skewYg(degree), a, b); // dojo.gfx.matrix.Matrix2D		}		// branch		// degree: Number: an skewing angle in degrees		// a: dojo.gfx.Point: a central point		// b: null		return dojo.gfx.matrix._sandwich(dojo.gfx.matrix.skewYg(degree), a.x, a.y); // dojo.gfx.matrix.Matrix2D	}		// TODO: rect-to-rect mapping, scale-to-fit (isotropic and anisotropic versions)	});