text: /**
  Copyright (c) 2010 Dennis Hotson
  
   Permission is hereby granted, free of charge, to any person
   obtaining a copy of this software and associated documentation
   files (the "Software"), to deal in the Software without
   restriction, including without limitation the rights to use,
   copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the
   Software is furnished to do so, subject to the following
   conditions:
  
   The above copyright notice and this permission notice shall be
   included in all copies or substantial portions of the Software.
  
   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
   OTHER DEALINGS IN THE SOFTWARE.
  */
  
  (function() {
  
  jQuery.fn.springy = function(params) {
  	var snapdistance = params.snapdistance || 0.5;
          var edge_label_color = params.edge_label_color || "#5BA6EC";
          var edge_default_color = params.edge_default_color || "#000000";
          var edge_deletion_color = params.edge_deletion_color || "#FF0000";
          var edge_creation_color = params.edge_creation_color || "#90B0FF";
          var edge_label_font = params.edge_label_font || "10px Helvetica, sans-serif";
          var node_default_color = params.node_default_color || "#FFFFFF";
          var node_hover_color = params.node_hover_color || "#FFFFFF";
          var node_selected_color = params.node_selected_color || "#FFFFFF";
          var node_border_default_color = params.node_border_default_color || "#000000";
          var node_border_hover_color = params.node_hover_color || "#406080";
          var node_border_selected_color = params.node_selected_color || "#90B0FF";
          var node_border_width = params.node_border_width || 2;
          var node_label_color = params.node_label_color || "#000000";
          var node_label_font = params.node_label_font || "16px Helvetica, sans-serif";
  
  	var graph = this.graph = params.graph || new Springy.Graph();
  
  	var stiffness = params.stiffness || 400.0;
  	var repulsion = params.repulsion || 400.0;
  	var damping = params.damping || 0.5;
  	var nodeSelected = params.nodeSelected || null;
  
  	var canvas = this[0];
  	var ctx = canvas.getContext("2d");
  
  	var layout = this.layout = new Springy.Layout.ForceDirected(graph, stiffness, repulsion, damping);
  
  	// calculate bounding box of graph layout.. with ease-in
  	var currentBB = layout.getBoundingBox();
  	var targetBB = {bottomleft: new Springy.Vector(-2, -2), topright: new Springy.Vector(2, 2)};
  
  	// auto adjusting bounding box
  	Springy.requestAnimationFrame(function adjust() {
  		targetBB = layout.getBoundingBox();
  		// current gets 20% closer to target every iteration
  		currentBB = {
  			bottomleft: currentBB.bottomleft.add( targetBB.bottomleft.subtract(currentBB.bottomleft)
  				.divide(10)),
  			topright: currentBB.topright.add( targetBB.topright.subtract(currentBB.topright)
  				.divide(10))
  		};
  
  		Springy.requestAnimationFrame(adjust);
  	});
  
  	// convert to/from screen coordinates
  	var toScreen = function(p) {
  		var size = currentBB.topright.subtract(currentBB.bottomleft);
  		var sx = p.subtract(currentBB.bottomleft).divide(size.x).x * canvas.width;
  		var sy = p.subtract(currentBB.bottomleft).divide(size.y).y * canvas.height;
  		return new Springy.Vector(sx, sy);
  	};
  
  	var fromScreen = function(s) {
  		var size = currentBB.topright.subtract(currentBB.bottomleft);
  		var px = (s.x / canvas.width) * size.x + currentBB.bottomleft.x;
  		var py = (s.y / canvas.height) * size.y + currentBB.bottomleft.y;
  		return new Springy.Vector(px, py);
  	};
  
  	// half-assed drag and drop
  	var selected = null;
  	var nearest = null;
  	var dragged = null;
  	var button = null;
  
  	jQuery(canvas).mousedown(function(e) {
  		var pos = jQuery(this).offset();
  		var p = fromScreen({x: e.pageX - pos.left, y: e.pageY - pos.top});
  		var nearestNode = layout.nearest(p);
  		if(nearestNode.distance <= snapdistance) {
  			selected = nearest = dragged = nearestNode;
  		} else {
  			selected = nearest = dragged = null;
  		}
  		button = e.button;
  
  		if (selected && selected.node !== null) {
  			dragged.point.m = 10000.0;
  
  			if (nodeSelected) {
  				nodeSelected(selected.node);
  			}
  		}
  
  		renderer.start();
  	});
  	
  	jQuery(canvas).bind('contextmenu', function(e) { return false; });
  
  	jQuery(canvas).dblclick(function(e) {
  		var pos = jQuery(this).offset();
  		var p = fromScreen({x: e.pageX - pos.left, y: e.pageY - pos.top});
  		var nearestNode = layout.nearest(p);
  		node = nearestNode.node;
  		
  		if(nearestNode.distance > 0.5) {
  			graph.newNode({p: p});
  		} else {
  			graph.removeNode(node);
  			if (node && node.data && node.data.ondoubleclick) {
  				node.data.ondoubleclick();
  			}
  		}
  	});
  
  	jQuery(canvas).mousemove(function(e) {
  		var pos = jQuery(this).offset();
  		var p = fromScreen({x: e.pageX - pos.left, y: e.pageY - pos.top});
  		nearest = layout.nearest(p);
  		
  		if (dragged !== null && dragged.node !== null) {
  			renderer.stop();
  
  			renderer.clear();
  
  			renderer.layout.eachEdge(function(edge, spring) {
  				renderer.drawEdge(edge, spring.point1.p, spring.point2.p);
  			});
  
  			var data = (button == 2) ? {color: edge_deletion_color} : {color: edge_creation_color};
  			data.directional = graph.params.directed;
  			if(nearest.distance > 0.5) {
  				var dummy_node = new Springy.Node(0, 0);
  				dummy_node.getRadius = function() { return 0.0 };
  				var edge = {source: dragged.node, target: dummy_node, data: data};
  				var p1 = dragged.point.p;
  				var p2 = p;
  			} else {
  				var edge = {source: dragged.node, target: nearest.node, data: data};
  				var p1 = dragged.point.p;
  				var p2 = nearest.point.p;
  			}
  		    renderer.drawEdge(edge, p1, p2);
  
  			renderer.layout.eachNode(function(node, point) {
  				renderer.drawNode(node, point.p);
  			});
  		} else {
  			renderer.start();
  		}
  	});
  
  	jQuery(window).bind('mouseup',function(e) {
  		selected = null;
  		if(dragged !== null && dragged !== nearest && nearest.distance <= snapdistance) {
  			if(button == 0) {
  				graph.newEdge(dragged.node, nearest.node, {});
  			} else if (button == 2) {
  				var edges;
  				while(1) {
  					edges = graph.getEdges(dragged.node, nearest.node);
  					if(edges.length == 0) {
  						break;
  					}
  					graph.removeEdge(edges[0]);
  				}
  			}
  		}
  		dragged = null;
  	});
  
  	Springy.Node.prototype.getWidth = function() {
  		var text = (this.data.label !== undefined) ? this.data.label : this.id;
  		if (this._width && this._width[text])
  			return this._width[text];
  
  		ctx.save();
  		ctx.font = node_label_font;
  		var width = ctx.measureText(text).width;
  		ctx.restore();
  
  		this._width || (this._width = {});
  		this._width[text] = width;
  
  		return width;
  	};
  
  	Springy.Node.prototype.getHeight = function() {
  		return 20;
  	};
  	
  	Springy.Node.prototype.getRadius = function() {
  		return 20;
  	};
  
  	var renderer = this.renderer = new Springy.Renderer(layout,
  		function clear() {
  			ctx.clearRect(0,0,canvas.width,canvas.height);
  		},
  		function drawEdge(edge, p1, p2) {
  			var x1 = toScreen(p1).x;
  			var y1 = toScreen(p1).y;
  			var x2 = toScreen(p2).x;
  			var y2 = toScreen(p2).y;
  
  			var direction = new Springy.Vector(x2-x1, y2-y1);
  			var normal = direction.normal().normalise();
  
  			var from = graph.getEdges(edge.source, edge.target);
  			var to = graph.getEdges(edge.target, edge.source);
  
  			var total = from.length + to.length;
  
  			// Figure out edge's position in relation to other edges between the same nodes
  			if(graph.params.simple && !graph.params.directed) {
  				var offset = new Springy.Vector(0, 0);
  			} else {
  				var n = 0;
  				for (var i=0; i<from.length; i++) {
  					if (from[i].id === edge.id) {
  						n = i;
  					}
  				}
  
  				var spacing = 6.0;
  
  				// Figure out how far off center the line should be drawn
  				var offset = normal.multiply(-((total - 1) * spacing)/2.0 + (n * spacing));
  			}
  
  			var s1 = toScreen(p1).add(offset);
  			var s2 = toScreen(p2).add(offset);
  
  			var radius = edge.target.getRadius();
  
  			var cntr = new Springy.Vector(x2, y2);
  			cntr = cntr.add(offset);
  			var intersection = intersect_line_circle(s1, s2, cntr, radius);
  
  			var stroke = (edge.data.color !== undefined) ? edge.data.color : edge_default_color;
  
  			var arrowWidth;
  			var arrowLength;
  
  			var weight = (edge.data.weight !== undefined) ? edge.data.weight : 1.0;
  
  			ctx.lineWidth = Math.max(weight *  2, 0.1);
  			arrowWidth = 1 + ctx.lineWidth;
  			arrowLength = 8;
  
  			var directional = (edge.data.directional !== undefined) ? edge.data.directional : true;
  
  			// line
  			var lineEnd;
  			if (directional) {
  				lineEnd = intersection.subtract(direction.normalise().multiply(arrowLength * 0.5));
  			} else {
  				lineEnd = s2;
  			}
  
  			ctx.strokeStyle = stroke;
  			ctx.beginPath();
  			ctx.moveTo(s1.x, s1.y);
  			ctx.lineTo(lineEnd.x, lineEnd.y);
  			ctx.stroke();
  
  			// arrow
  			if (directional) {
  				ctx.save();
  				ctx.fillStyle = stroke;
  				ctx.translate(intersection.x, intersection.y);
  				ctx.rotate(Math.atan2(y2 - y1, x2 - x1));
  				ctx.beginPath();
  				ctx.moveTo(-arrowLength, arrowWidth);
  				ctx.lineTo(0, 0);
  				ctx.lineTo(-arrowLength, -arrowWidth);
  				ctx.lineTo(-arrowLength * 0.8, -0);
  				ctx.closePath();
  				ctx.fill();
  				ctx.restore();
  			}
  
  			// label
  			if (edge.data.label !== undefined) {
  				text = edge.data.label
  				ctx.save();
  				ctx.textAlign = "center";
  				ctx.textBaseline = "top";
  				ctx.font = edge_label_font;
  				ctx.fillStyle = edge_label_color;
  				ctx.fillText(text, (x1+x2)/2, (y1+y2)/2);
  				ctx.restore();
  			}
  
  		},
  		function drawNode(node, p) {
  			var s = toScreen(p);
  
  			ctx.save();
  
  			var labelWidth = node.getWidth();
  			var radius = node.getRadius();
  
  			// fill background
                          var node_color = (node.data.color !== undefined) ? node.data.color : node_default_color;
                          var node_border_color = (node.data.border_color !== undefined) ? node.data.border_color : node_border_default_color;
  			if (selected !== null && nearest !== null && nearest.node !== null && selected.node.id === node.id) {
  				ctx.strokeStyle = (node_border_selected_color !== undefined) ? node_border_selected_color : node_border_color;
  			        ctx.fillStyle = (node_selected_color !== undefined) ? node_selected_color : node_color;
  			} else if (nearest !== null && nearest !== null && nearest.node !== null && nearest.node.id === node.id && nearest.distance <= snapdistance) {
  				ctx.strokeStyle = (node_border_hover_color !== undefined) ? node_border_hover_color : node_border_color;
  			        ctx.fillStyle = (node_hover_color !== undefined) ? node_hover_color : node_color;
  			} else {
  				ctx.strokeStyle = node_border_color;
  			        ctx.fillStyle = node_color;
  			}
                          ctx.lineWidth = node_border_width;
  			ctx.beginPath();
  			ctx.arc(s.x, s.y, radius, 0, 2 * Math.PI, false);
  			ctx.fill();
                          if(node_border_width > 0) {
                              ctx.stroke();
                          }
  
  			ctx.textAlign = "left";
  			ctx.textBaseline = "top";
  			ctx.font = node_label_font;
  			ctx.fillStyle = node_label_color;
  			ctx.font = node_label_font;
  			var text = (node.data.label !== undefined) ? node.data.label : node.id;
  			var x = (labelWidth - 15 > radius) ? s.x + radius + 8 : s.x - labelWidth/2;
  			ctx.fillText(text, x, s.y - 8);
  
  			ctx.restore();
  		}
  	);
  
  	renderer.start();
  
  	// helpers for figuring out where to draw arrows
  	function intersect_line_line(p1, p2, p3, p4) {
  		var denom = ((p4.y - p3.y)*(p2.x - p1.x) - (p4.x - p3.x)*(p2.y - p1.y));
  
  		// lines are parallel
  		if (denom === 0) {
  			return false;
  		}
  
  		var ua = ((p4.x - p3.x)*(p1.y - p3.y) - (p4.y - p3.y)*(p1.x - p3.x)) / denom;
  		var ub = ((p2.x - p1.x)*(p1.y - p3.y) - (p2.y - p1.y)*(p1.x - p3.x)) / denom;
  
  		if (ua < 0 || ua > 1 || ub < 0 || ub > 1) {
  			return false;
  		}
  
  		return new Springy.Vector(p1.x + ua * (p2.x - p1.x), p1.y + ua * (p2.y - p1.y));
  	}
  
  	function intersect_line_box(p1, p2, p3, w, h) {
  		var tl = {x: p3.x, y: p3.y};
  		var tr = {x: p3.x + w, y: p3.y};
  		var bl = {x: p3.x, y: p3.y + h};
  		var br = {x: p3.x + w, y: p3.y + h};
  
  		var result;
  		if (result = intersect_line_line(p1, p2, tl, tr)) { return result; } // top
  		if (result = intersect_line_line(p1, p2, tr, br)) { return result; } // right
  		if (result = intersect_line_line(p1, p2, br, bl)) { return result; } // bottom
  		if (result = intersect_line_line(p1, p2, bl, tl)) { return result; } // left
  
  		return false;
  	}
  
  	function intersect_line_circle(p1, p2, p3, radius) {
  		var p1dist = p1.subtract(p3).magnitude();
  		var p2dist = p2.subtract(p3).magnitude();
  		
  		if(p1dist >= radius && p2dist <= radius) {
  			line = p3.subtract(p1);
  			line = line.multiply((line.magnitude() - radius) / line.magnitude());
  			return line.add(p1);
  		} else if(p1dist <= radius && p2dist >= radius) {
  			line = p3.subtract(p2);
  			line = line.multiply((line.magnitude() - radius) / line.magnitude());
  			return line.add(p2);
  		} else {
  			return p3;
  		}
  	}
  	
  	return this;
  }
  
  })();
  