dojo.provide("dojox.gfx.matrix");

(function(){
	var m = dojox.gfx.matrix;
	
	// candidates for dojox.math:
	m._degToRad = function(degree){ return Math.PI * degree / 180; };
	m._radToDeg = function(radian){ return radian / Math.PI * 180; };

	m.Matrix2D = function(arg){
		// summary: a 2D matrix object
		// description: Normalizes a 2D matrix-like object. If arrays is passed, 
		//		all objects of the array are normalized and multiplied sequentially.
		// arg: Object
		//		a 2D matrix-like object, a number, or an array of such objects
		if(arg){
			if(typeof arg == "number"){
				this.xx = this.yy = arg;
			}else if(arg instanceof Array){
				if(arg.length > 0){
					var matrix = m.normalize(arg[0]);
					// combine matrices
					for(var i = 1; i < arg.length; ++i){
						var l = matrix, r = dojox.gfx.matrix.normalize(arg[i]);
						matrix = new m.Matrix2D();
						matrix.xx = l.xx * r.xx + l.xy * r.yx;
						matrix.xy = l.xx * r.xy + l.xy * r.yy;
						matrix.yx = l.yx * r.xx + l.yy * r.yx;
						matrix.yy = l.yx * r.xy + l.yy * r.yy;
						matrix.dx = l.xx * r.dx + l.xy * r.dy + l.dx;
						matrix.dy = l.yx * r.dx + l.yy * r.dy + l.dy;
					}
					dojo.mixin(this, matrix);
				}
			}else{
				dojo.mixin(this, arg);
			}
		}
	};

	// the default (identity) matrix, which is used to fill in missing values
	dojo.extend(m.Matrix2D, {xx: 1, xy: 0, yx: 0, yy: 1, dx: 0, dy: 0});

	dojo.mixin(m, {
		// summary: class constants, and methods of dojox.gfx.matrix
		
		// matrix constants
		
		// identity: dojox.gfx.matrix.Matrix2D
		//		an identity matrix constant: identity * (x, y) == (x, y)
		identity: new m.Matrix2D(),
		
		// flipX: dojox.gfx.matrix.Matrix2D
		//		a matrix, which reflects points at x = 0 line: flipX * (x, y) == (-x, y)
		flipX:    new m.Matrix2D({xx: -1}),
		
		// flipY: dojox.gfx.matrix.Matrix2D
		//		a matrix, which reflects points at y = 0 line: flipY * (x, y) == (x, -y)
		flipY:    new m.Matrix2D({yy: -1}),
		
		// flipXY: dojox.gfx.matrix.Matrix2D
		//		a matrix, which reflects points at the origin of coordinates: flipXY * (x, y) == (-x, -y)
		flipXY:   new m.Matrix2D({xx: -1, yy: -1}),
		
		// matrix creators
		
		translate: function(a, b){
			// summary: forms a translation matrix
			// description: The resulting matrix is used to translate (move) points by specified offsets.
			// a: Number: an x coordinate value
			// b: Number: a y coordinate value
			if(arguments.length > 1){
				return new m.Matrix2D({dx: a, dy: b}); // dojox.gfx.matrix.Matrix2D
			}
			// branch
			// a: dojox.gfx.Point: a point-like object, which specifies offsets for both dimensions
			// b: null
			return new m.Matrix2D({dx: a.x, dy: a.y}); // dojox.gfx.matrix.Matrix2D
		},
		scale: function(a, b){
			// summary: forms a scaling matrix
			// description: The resulting matrix is used to scale (magnify) points by specified offsets.
			// a: Number: a scaling factor used for the x coordinate
			// b: Number: a scaling factor used for the y coordinate
			if(arguments.length > 1){
				return new m.Matrix2D({xx: a, yy: b}); // dojox.gfx.matrix.Matrix2D
			}
			if(typeof a == "number"){
				// branch
				// a: Number: a uniform scaling factor used for the both coordinates
				// b: null
				return new m.Matrix2D({xx: a, yy: a}); // dojox.gfx.matrix.Matrix2D
			}
			// branch
			// a: dojox.gfx.Point: a point-like object, which specifies scale factors for both dimensions
			// b: null
			return new m.Matrix2D({xx: a.x, yy: a.y}); // dojox.gfx.matrix.Matrix2D
		},
		rotate: function(angle){
			// summary: forms a rotating matrix
			// description: The resulting matrix is used to rotate points 
			//		around the origin of coordinates (0, 0) by specified angle.
			// angle: Number: an angle of rotation in radians (>0 for CW)
			var c = Math.cos(angle);
			var s = Math.sin(angle);
			return new m.Matrix2D({xx: c, xy: -s, yx: s, yy: c}); // dojox.gfx.matrix.Matrix2D
		},
		rotateg: function(degree){
			// summary: forms a rotating matrix
			// description: The resulting matrix is used to rotate points
			//		around the origin of coordinates (0, 0) by specified degree.
			//		See dojox.gfx.matrix.rotate() for comparison.
			// degree: Number: an angle of rotation in degrees (>0 for CW)
			return m.rotate(m._degToRad(degree)); // dojox.gfx.matrix.Matrix2D
		},
		skewX: function(angle) {
			// summary: forms an x skewing matrix
			// description: The resulting matrix is used to skew points in the x dimension
			//		around the origin of coordinates (0, 0) by specified angle.
			// angle: Number: an skewing angle in radians
			return new m.Matrix2D({xy: -Math.tan(angle)}); // dojox.gfx.matrix.Matrix2D
		},
		skewXg: function(degree){
			// summary: forms an x skewing matrix
			// description: The resulting matrix is used to skew points in the x dimension
			//		around the origin of coordinates (0, 0) by specified degree.
			//		See dojox.gfx.matrix.skewX() for comparison.
			// degree: Number: an skewing angle in degrees
			return m.skewX(m._degToRad(degree)); // dojox.gfx.matrix.Matrix2D
		},
		skewY: function(angle){
			// summary: forms a y skewing matrix
			// description: The resulting matrix is used to skew points in the y dimension
			//		around the origin of coordinates (0, 0) by specified angle.
			// angle: Number: an skewing angle in radians
			return new m.Matrix2D({yx: Math.tan(angle)}); // dojox.gfx.matrix.Matrix2D
		},
		skewYg: function(degree){
			// summary: forms a y skewing matrix
			// description: The resulting matrix is used to skew points in the y dimension
			//		around the origin of coordinates (0, 0) by specified degree.
			//		See dojox.gfx.matrix.skewY() for comparison.
			// degree: Number: an skewing angle in degrees
			return m.skewY(m._degToRad(degree)); // dojox.gfx.matrix.Matrix2D
		},
		reflect: function(a, b){
			// summary: forms a reflection matrix
			// description: The resulting matrix is used to reflect points around a vector, 
			//		which goes through the origin.
			// a: dojox.gfx.Point: a point-like object, which specifies a vector of reflection
			// b: null
			if(arguments.length == 1){
				b = a.y;
				a = a.x;
			}
			// branch
			// a: Number: an x coordinate value
			// b: Number: a y coordinate value
			
			// make a unit vector
			var a2 = a * a, b2 = b * b, n2 = a2 + b2, xy = 2 * a * b / n2;
			return new m.Matrix2D({xx: 2 * a2 / n2 - 1, xy: xy, yx: xy, yy: 2 * b2 / n2 - 1}); // dojox.gfx.matrix.Matrix2D
		},
		project: function(a, b){
			// summary: forms an orthogonal projection matrix
			// description: The resulting matrix is used to project points orthogonally on a vector, 
			//		which goes through the origin.
			// a: dojox.gfx.Point: a point-like object, which specifies a vector of projection
			// b: null
			if(arguments.length == 1){
				b = a.y;
				a = a.x;
			}
			// branch
			// a: Number: an x coordinate value
			// b: Number: a y coordinate value
			
			// make a unit vector
			var a2 = a * a, b2 = b * b, n2 = a2 + b2, xy = a * b / n2;
			return new m.Matrix2D({xx: a2 / n2, xy: xy, yx: xy, yy: b2 / n2}); // dojox.gfx.matrix.Matrix2D
		},
		
		// ensure matrix 2D conformance
		normalize: function(matrix){
			// summary: converts an object to a matrix, if necessary
			// description: Converts any 2D matrix-like object or an array of
			//		such objects to a valid dojox.gfx.matrix.Matrix2D object.
			// matrix: Object: an object, which is converted to a matrix, if necessary
			return (matrix instanceof m.Matrix2D) ? matrix : new m.Matrix2D(matrix); // dojox.gfx.matrix.Matrix2D
		},
		
		// common operations
		
		clone: function(matrix){
			// summary: creates a copy of a 2D matrix
			// matrix: dojox.gfx.matrix.Matrix2D: a 2D matrix-like object to be cloned
			var obj = new m.Matrix2D();
			for(var i in matrix){
				if(typeof(matrix[i]) == "number" && typeof(obj[i]) == "number" && obj[i] != matrix[i]) obj[i] = matrix[i];
			}
			return obj; // dojox.gfx.matrix.Matrix2D
		},
		invert: function(matrix){
			// summary: inverts a 2D matrix
			// matrix: dojox.gfx.matrix.Matrix2D: a 2D matrix-like object to be inverted
			var M = m.normalize(matrix),
				D = M.xx * M.yy - M.xy * M.yx,
				M = new m.Matrix2D({
					xx: M.yy/D, xy: -M.xy/D, 
					yx: -M.yx/D, yy: M.xx/D, 
					dx: (M.xy * M.dy - M.yy * M.dx) / D, 
					dy: (M.yx * M.dx - M.xx * M.dy) / D
				});
			return M; // dojox.gfx.matrix.Matrix2D
		},
		_multiplyPoint: function(matrix, x, y){
			// summary: applies a matrix to a point
			// matrix: dojox.gfx.matrix.Matrix2D: a 2D matrix object to be applied
			// x: Number: an x coordinate of a point
			// y: Number: a y coordinate of a point
			return {x: matrix.xx * x + matrix.xy * y + matrix.dx, y: matrix.yx * x + matrix.yy * y + matrix.dy}; // dojox.gfx.Point
		},
		multiplyPoint: function(matrix, /* Number||Point */ a, /* Number, optional */ b){
			// summary: applies a matrix to a point
			// matrix: dojox.gfx.matrix.Matrix2D: a 2D matrix object to be applied
			// a: Number: an x coordinate of a point
			// b: Number: a y coordinate of a point
			var M = m.normalize(matrix);
			if(typeof a == "number" && typeof b == "number"){
				return m._multiplyPoint(M, a, b); // dojox.gfx.Point
			}
			// branch
			// matrix: dojox.gfx.matrix.Matrix2D: a 2D matrix object to be applied
			// a: dojox.gfx.Point: a point
			// b: null
			return m._multiplyPoint(M, a.x, a.y); // dojox.gfx.Point
		},
		multiply: function(matrix){
			// summary: combines matrices by multiplying them sequentially in the given order
			// matrix: dojox.gfx.matrix.Matrix2D...: a 2D matrix-like object, 
			//		all subsequent arguments are matrix-like objects too
			var M = m.normalize(matrix);
			// combine matrices
			for(var i = 1; i < arguments.length; ++i){
				var l = M, r = m.normalize(arguments[i]);
				M = new m.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; // dojox.gfx.matrix.Matrix2D
		},
		
		// high level operations
		
		_sandwich: function(matrix, x, y){
			// summary: applies a matrix at a centrtal point
			// matrix: dojox.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 m.multiply(m.translate(x, y), matrix, m.translate(-x, -y)); // dojox.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 dojox.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 m._sandwich(m.scale(a, b), c, d); // dojox.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 m._sandwich(m.scale(a), b, c); // dojox.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: dojox.gfx.Point: a central point
					// d: null
					return m._sandwich(m.scale(a, b), c.x, c.y); // dojox.gfx.matrix.Matrix2D
			}
			// branch
			// a: Number: a uniform scaling factor used for both coordinates
			// b: dojox.gfx.Point: a central point
			// c: null
			// d: null
			return m._sandwich(m.scale(a), b.x, b.y); // dojox.gfx.matrix.Matrix2D
		},
		rotateAt: function(angle, a, b){
			// summary: rotates a picture using a specified point as a center of rotation
			// description: Compare with dojox.gfx.matrix.rotate().
			// angle: Number: an angle of rotation in radians (>0 for CW)
			// 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 m._sandwich(m.rotate(angle), a, b); // dojox.gfx.matrix.Matrix2D
			}
			
			// branch
			// angle: Number: an angle of rotation in radians (>0 for CCW)
			// a: dojox.gfx.Point: a central point
			// b: null
			return m._sandwich(m.rotate(angle), a.x, a.y); // dojox.gfx.matrix.Matrix2D
		},
		rotategAt: function(degree, a, b){
			// summary: rotates a picture using a specified point as a center of rotation
			// description: Compare with dojox.gfx.matrix.rotateg().
			// degree: Number: an angle of rotation in degrees (>0 for CW)
			// 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 m._sandwich(m.rotateg(degree), a, b); // dojox.gfx.matrix.Matrix2D
			}

			// branch
			// degree: Number: an angle of rotation in degrees (>0 for CCW)
			// a: dojox.gfx.Point: a central point
			// b: null
			return m._sandwich(m.rotateg(degree), a.x, a.y); // dojox.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 dojox.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 m._sandwich(m.skewX(angle), a, b); // dojox.gfx.matrix.Matrix2D
			}

			// branch
			// angle: Number: an skewing angle in radians
			// a: dojox.gfx.Point: a central point
			// b: null
			return m._sandwich(m.skewX(angle), a.x, a.y); // dojox.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 dojox.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 m._sandwich(m.skewXg(degree), a, b); // dojox.gfx.matrix.Matrix2D
			}

			// branch
			// degree: Number: an skewing angle in degrees
			// a: dojox.gfx.Point: a central point
			// b: null
			return m._sandwich(m.skewXg(degree), a.x, a.y); // dojox.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 dojox.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 m._sandwich(m.skewY(angle), a, b); // dojox.gfx.matrix.Matrix2D
			}

			// branch
			// angle: Number: an skewing angle in radians
			// a: dojox.gfx.Point: a central point
			// b: null
			return m._sandwich(m.skewY(angle), a.x, a.y); // dojox.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 dojox.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 m._sandwich(m.skewYg(degree), a, b); // dojox.gfx.matrix.Matrix2D
			}

			// branch
			// degree: Number: an skewing angle in degrees
			// a: dojox.gfx.Point: a central point
			// b: null
			return m._sandwich(m.skewYg(degree), a.x, a.y); // dojox.gfx.matrix.Matrix2D
		}
		
		//TODO: rect-to-rect mapping, scale-to-fit (isotropic and anisotropic versions)
		
	});
})();

// propagate Matrix2D up
dojox.gfx.Matrix2D = dojox.gfx.matrix.Matrix2D;
