path.js

ajax-dwr方式的即时消息演示程序 jsp-servlet,ajax技术实现

/*
	Copyright (c) 2004-2006, The Dojo Foundation
	All Rights Reserved.

	Licensed under the Academic Free License version 2.1 or above OR the
	modified BSD license. For more information on Dojo licensing, see:

		http://dojotoolkit.org/community/licensing.shtml
*/

dojo.provide("dojo.gfx.path");

dojo.require("dojo.math");

dojo.require("dojo.gfx.shape");

dojo.declare("dojo.gfx.path.Path", dojo.gfx.Shape, {
	// summary:
	//		a path shape
	initializer: function(/* Node */ rawNode){
		// summary: a constructor of a path shape object
		// rawNode: a DOM node to be used by this path object
		this.shape = dojo.lang.shallowCopy(dojo.gfx.defaultPath, true);
		this.segments = [];
		this.absolute = true;
		this.last = {};
		this.attach(rawNode);
	},
	
	// mode manipulations
	setAbsoluteMode: function(/* Boolean||String */ mode){
		// summary: sets an absolute or relative mode for path points
		// mode: true/false or "absolute"/"relative" to specify the mode
		this.absolute = typeof(mode) == "string" ? (mode == "absolute") : mode;
		return this; // self
	},
	getAbsoluteMode: function(){
		// summary: returns a current value of the absolute mode
		return this.absolute; // Boolean
	},
	getBoundingBox: function(){
		// summary: returns a bounding box {x, y, width, height} or null
		return "l" in this.bbox ? {x: this.bbox.l, y: this.bbox.t, width: this.bbox.r - this.bbox.l, height: this.bbox.b - this.bbox.t} : null; // Object
	},
	getLastPosition: function(){
		// summary: returns the last point in the path, or null
		return "x" in this.last ? this.last : null; // Object
	},
	
	// segment interpretation
	_updateBBox: function(/* Number */ x, /* Number */ y){
		// summary: updates a bounding box of path with new point
		
		// we use {l, b, r, t} representation of a bbox
		if("l" in this.bbox){
			if(this.bbox.l > x) this.bbox.l = x;
			if(this.bbox.r < x) this.bbox.r = x;
			if(this.bbox.t > y) this.bbox.t = y;
			if(this.bbox.b < y) this.bbox.b = y;
		}else{
			this.bbox = {l: x, b: y, r: x, t: y};
		}
	},
	_updateWithSegment: function(/* Object */ segment){
		// summary: updates a bounding box of path with new segment
		var n = segment.args;
		var l = n.length;
		// update internal variables: bbox, absolute, last
		switch(segment.action){
			case "M":
			case "L":
			case "C":
			case "S":
			case "Q":
			case "T":
				for(var i = 0; i < l; i += 2){
					this._updateBBox(this.bbox, n[i], n[i + 1]);
				}
				this.last.x = n[l - 2];
				this.last.y = n[l - 1];
				this.absolute = true;
				break;
			case "H":
				for(var i = 0; i < l; ++i){
					this._updateBBox(this.bbox, n[i], this.last.y);
				}
				this.last.x = n[l - 1];
				this.absolute = true;
				break;
			case "V":
				for(var i = 0; i < l; ++i){
					this._updateBBox(this.bbox, this.last.x, n[i]);
				}
				this.last.y = n[l - 1];
				this.absolute = true;
				break;
			case "m":
				var start = 0;
				if(!("x" in this.last)){
					this._updateBBox(this.bbox, this.last.x = n[0], this.last.y = n[1]);
					start = 2;
				}
				for(var i = start; i < l; i += 2){
					this._updateBBox(this.bbox, this.last.x += n[i], this.last.y += n[i + 1]);
				}
				this.absolute = false;
				break;
			case "l":
			case "t":
				for(var i = 0; i < l; i += 2){
					this._updateBBox(this.bbox, this.last.x += n[i], this.last.y += n[i + 1]);
				}
				this.absolute = false;
				break;
			case "h":
				for(var i = 0; i < l; ++i){
					this._updateBBox(this.bbox, this.last.x += n[i], this.last.y);
				}
				this.absolute = false;
				break;
			case "v":
				for(var i = 0; i < l; ++i){
					this._updateBBox(this.bbox, this.last.x, this.last.y += n[i]);
				}
				this.absolute = false;
				break;
			case "c":
				for(var i = 0; i < l; i += 6){
					this._updateBBox(this.bbox, this.last.x + n[i], this.last.y + n[i + 1]);
					this._updateBBox(this.bbox, this.last.x + n[i + 2], this.last.y + n[i + 3]);
					this._updateBBox(this.bbox, this.last.x += n[i + 4], this.last.y += n[i + 5]);
				}
				this.absolute = false;
				break;
			case "s":
			case "q":
				for(var i = 0; i < l; i += 4){
					this._updateBBox(this.bbox, this.last.x + n[i], this.last.y + n[i + 1]);
					this._updateBBox(this.bbox, this.last.x += n[i + 2], this.last.y += n[i + 3]);
				}
				this.absolute = false;
				break;
			case "A":
				for(var i = 0; i < l; i += 7){
					this._updateBBox(this.bbox, n[i + 5], n[i + 6]);
				}
				this.last.x = n[l - 2];
				this.last.y = n[l - 1];
				this.absolute = true;
				break;
			case "a":
				for(var i = 0; i < l; i += 7){
					this._updateBBox(this.bbox, this.last.x += n[i + 5], this.last.y += n[i + 6]);
				}
				this.absolute = false;
				break;
		}
		// add an SVG path segment
		var path = [segment.action];
		for(var i = 0; i < l; ++i){
			path.push(dojo.gfx.formatNumber(n[i], true));
		}
		if(typeof(this.shape.path) == "string"){
			this.shape.path += path.join("");
		}else{
			this.shape.path = this.shape.path.concat(path);
		}
	},
	// a dictionary, which maps segment type codes to a number of their argemnts
	_validSegments: {m: 2, l: 2, h: 1, v: 1, c: 6, s: 4, q: 4, t: 2, a: 7, z: 0},
	_pushSegment: function(/* String */ action, /* Array */ args){
		// summary: adds a segment
		// action: valid SVG code for a segment's type
		// args: a list of parameters for this segment
		var group = this._validSegments[action.toLowerCase()];
		if(typeof(group) == "number"){
			if(group){
				if(args.length >= group){
					var segment = {action: action, args: args.slice(0, args.length - args.length % group)};
					this.segments.push(segment);
					this._updateWithSegment(segment);
				}
			}else{
				var segment = {action: action, args: []};
				this.segments.push(segment);
				this._updateWithSegment(segment);
			}
		}
	},
	_collectArgs: function(/* Array */ array, /* Array */ args){
		// summary: converts an array of arguments to plain numeric values
		for(var i = 0; i < args.length; ++i){
			var t = args[i];
			if(typeof(t) == "boolean"){
				array.push(t ? 1 : 0);
			}else if(typeof(t) == "number"){
				array.push(t);
			}else if(t instanceof Array){
				this._collectArgs(array, t);
			}else if("x" in t && "y" in t){
				array.push(t.x);
				array.push(t.y);
			}
		}
	},

	// segments	
	moveTo: function(){
		// summary: formes a move segment
		var args = [];
		this._collectArgs(args, arguments);
		this._pushSegment(this.absolute ? "M" : "m", args);
		return this; // self
	},
	lineTo: function(){
		// summary: formes a line segment
		var args = [];
		this._collectArgs(args, arguments);
		this._pushSegment(this.absolute ? "L" : "l", args);
		return this; // self
	},
	hLineTo: function(){
		// summary: formes a horizontal line segment
		var args = [];
		this._collectArgs(args, arguments);
		this._pushSegment(this.absolute ? "H" : "h", args);
		return this; // self
	},
	vLineTo: function(){
		// summary: formes a vertical line segment
		var args = [];
		this._collectArgs(args, arguments);
		this._pushSegment(this.absolute ? "V" : "v", args);
		return this; // self
	},
	curveTo: function(){
		// summary: formes a curve segment
		var args = [];
		this._collectArgs(args, arguments);
		this._pushSegment(this.absolute ? "C" : "c", args);
		return this; // self
	},
	smoothCurveTo: function(){
		// summary: formes a smooth curve segment
		var args = [];
		this._collectArgs(args, arguments);
		this._pushSegment(this.absolute ? "S" : "s", args);
		return this; // self
	},
	qCurveTo: function(){
		// summary: formes a quadratic curve segment
		var args = [];
		this._collectArgs(args, arguments);
		this._pushSegment(this.absolute ? "Q" : "q", args);
		return this; // self
	},
	qSmoothCurveTo: function(){
		// summary: formes a quadratic smooth curve segment
		var args = [];
		this._collectArgs(args, arguments);
		this._pushSegment(this.absolute ? "T" : "t", args);
		return this; // self
	},
	arcTo: function(){
		// summary: formes an elliptic arc segment
		var args = [];
		this._collectArgs(args, arguments);
		for(var i = 2; i < args.length; i += 7){
			args[i] = -args[i];
		}
		this._pushSegment(this.absolute ? "A" : "a", args);
		return this; // self
	},
	closePath: function(){
		// summary: closes a path
		this._pushSegment("Z", []);
		return this; // self
	},
	
	// setShape
	_setPath: function(path){
		// summary: forms a path using an SVG path string
		var p = path.match(dojo.gfx.pathRegExp);
		this.segments = [];
		this.absolute = true;
		this.bbox = {};
		this.last = {};
		if(!p) return;
		// create segments
		var action = "";	// current action
		var args = [];		// current arguments
		for(var i = 0; i < p.length; ++i){
			var t = p[i];
			var x = parseFloat(t);
			if(isNaN(x)){
				if(action){
					this._pushSegment(action, args);
				}
				args = [];
				action = t;
			}else{
				args.push(x);
			}
		}
		this._pushSegment(action, args);
	},
	setShape: function(newShape){
		// summary: forms a path using a shape
		this.shape = dojo.gfx.makeParameters(this.shape, typeof(newShape) == "string" ? {path: newShape} : newShape);
		var path = this.shape.path;
		// switch to non-updating version of path building
		this.shape.path = [];
		this._setPath(path);
		// switch back to the string path
		this.shape.path = this.shape.path.join("");
		return this; // self
	},
	
	_2PI: Math.PI * 2 // useful constant for descendants
});