add Rectangle type

spec/index.html

@@ -15,6 +15,7 @@
 
   <!-- include spec files here... -->
   <script type="text/javascript" src="spec/SvgMathFunctionSpec.js"></script>
+  <script type="text/javascript" src="spec/SvgMathRectangle.js"></script>
 
   <script type="text/javascript">
     (function() {

spec/spec/SvgMathRectangle.js

@@ -0,0 +1,52 @@
+describe('SVG.math.Rectangle', function() {
+	var Point = SVG.math.Point;
+	var Rectangle = SVG.math.Rectangle;
+	var p1 = new Point(-1,-2);
+	var p2 = new Point(-1,2);
+	var p3 = new Point(1,-2);
+	var p4 = new Point(1,2);
+	var rect1 = new Rectangle(p1,p4);
+
+	it('knows its dimensions', function() {
+ 		expect(rect1.xmin).toEqual(-1);
+ 		expect(rect1.ymin).toEqual(-2);
+ 		expect(rect1.xmax).toEqual(1);
+ 		expect(rect1.ymax).toEqual(2);
+ 		expect(rect1.width).toEqual(2);
+ 		expect(rect1.height).toEqual(4);
+ 		expect(rect1.area()).toEqual(8);
+	})
+
+	it('can be constructed with any pair of opposite corners', function() {
+ 		expect(new Rectangle(p2,p3)).toEqual(rect1);
+ 		expect(new Rectangle(p3,p2)).toEqual(rect1);
+ 		expect(new Rectangle(p4,p1)).toEqual(rect1);
+ 		expect(new Rectangle(p1,p2)).not.toEqual(rect1);
+	});
+
+	it('can have zero width', function() {
+ 		var rect5 = new Rectangle(p1,p2);
+ 		expect(rect5.xmin).toEqual(-1);
+ 		expect(rect5.ymin).toEqual(-2);
+ 		expect(rect5.xmax).toEqual(-1);
+ 		expect(rect5.ymax).toEqual(2);
+ 		expect(rect5.width).toEqual(0);
+ 		expect(rect5.height).toEqual(4);
+ 		expect(rect5.area()).toEqual(0);
+	});
+
+	it ('knows what points it contains', function() {
+		expect(rect1.contains(new Point(0.5,1.5))).toBe(true);
+		expect(rect1.contains(new Point(1.5,0.5))).toBe(false);
+		expect(rect1.contains(new Point(0.5,2.5))).toBe(false);
+	})
+
+	it ('knows what rectangles it intersects', function() {
+		expect(rect1.intersects(rect1)).toBe(true);
+		expect(rect1.intersects(new Rectangle(new Point(-3,-4),new Point(3,-3)))).toBe(false);
+		expect(rect1.intersects(new Rectangle(new Point(-3,-4),new Point(3,1)))).toBe(true);
+		expect(rect1.intersects(new Rectangle(new Point(-3,-4),new Point(3,4)))).toBe(true);
+		expect(rect1.intersects(new Rectangle(new Point(-3,-4),new Point(3,4)))).toBe(true);
+	})
+});
+

svg.math.js

@@ -211,7 +211,81 @@
 				)
 			);
 		}
-
 	});
 
+
+
+
+	/********** AXIS-PARALLEL RECTANGLE *************/
+
+	/**
+	 * Construct a rectangle from two opposite corners (points)
+	 */
+	SVG.math.Rectangle = function Rectangle(corner1, corner2) {
+		this.xmin = Math.min(corner1.x,corner2.x);
+		this.xmax = Math.max(corner1.x,corner2.x);
+		this.ymin = Math.min(corner1.y,corner2.y);
+		this.ymax = Math.max(corner1.y,corner2.y);
+
+		this.width = this.xmax-this.xmin;
+		this.height = this.ymax-this.ymin;
+	};
+
+	/**
+	 * Default draw attributes
+	 */
+	SVG.math.Rectangle.attr = {
+		stroke: '#000',
+		fill: 'none',
+	};
+
+	SVG.extend(SVG.math.Rectangle, {
+		/**
+		 * With a single parameter - draw a rectangle with default attributes.
+		 * With two parameters - draw a rectangle with the given attributes.  
+		 */
+		draw: function(svg, attr) {
+			attr = attr || SVG.math.Rectangle.attr;
+			this.svg = svg;
+			this.rectangle = svg.rect(this.width,this.height).move(this.xmin,this.ymin).attr(attr);
+			return this;
+		},
+
+		/**
+		 * remove the currently drawn rectangle. 
+		 */
+		remove: function() {
+			if (this.rectangle) {
+				this.rectangle.remove();
+				delete this.svg;
+				delete this.rectangle;
+			}
+		},
+
+		/**
+		 * @return true if this rectangle interior-contains the given point
+		 */
+		contains: function(point) {
+			var xcontains = this.xmin<point.x && point.x<this.xmax;
+			var ycontains = this.ymin<point.y && point.y<this.ymax;
+			return ycontains && xcontains;
+		},
+
+		/**
+		 * @return true if this rectangle interior-intersects the other rectangle
+		 */
+		intersects: function(other) {
+			var xintersects = this.xmax>other.xmin && other.xmax>this.xmin;
+			var yintersects = this.ymax>other.ymin && other.ymax>this.ymin;
+			return yintersects && xintersects;
+		},
+
+		/**
+		 * @return the area of this rectangle.
+		 */
+		area: function() {
+			return this.width*this.height;
+		}
+	});
+
 })();