本文介绍了一种使用ActionScript绘制特定军标的算法思想。该算法基于贝塞尔曲线原理，通过前端绘制多边形并将其转化为XML字符串，再经由BlazeDS传输至后端Java处理并保存至数据库。
前几天说要传军标
的算法思想呢，结果有事耽误了，现在我
把我军标
思想给说一下。
首先利用的技术：前端as语言绘制军标
（其实就是个多边
形），把多边形的点组成 XML字符串《这里也可以传对象，但是在后台java段也要有相同的对应对象》通过BlazeDS的
RemoteObject方式传到后台。
后台可以通过java保存到数据库中，这个最好是保存为Clob字段。
下面我把关键代码给大家分享一下。。
# //处理鼠标单击事件
# public function map_mouseClickHandler(event:MouseEvent):void
# {
# map.mapNavigationEnabled=false;
# //确定点击的地图点的坐标，然后放到数组中
# var m_point:MapPoint=map.toMapFromStage(event.stageX, event.stageY);
# if (m_firstpoints == null)
# {
# m_firstpoints=new Array();
# }
# m_firstpoints.push(m_point);
# }
# //处理鼠标双击事件
# public function map_mouseDoubleClickHandler(event:MouseEvent):void
# {
# m_gbjGeometry=new Polyline();
# //定义军标的多边形
# if (m_firstpoints.length <= 2)
# {
# m_firstpoints.splice(0);
# Alert.show("请最少点击三个点才能完成对军标的画法", "Error INFO");
# return;
# }
# //根据贝塞尔曲线算法来画线和面
# drawBezierCurve();
# //形成graphic
# full_polygon_graphic=new Graphic(full_gbjpolygon, gbjSymbol);
# full_polygon_graphic.toolTip="gbj";
# full_gbjpolygon.spatialReference=map.spatialReference;
# graphicsLayer.add(full_polygon_graphic);
# map.removeEventListener(MouseEvent.CLICK, map_mouseClickHandler);
# map.removeEventListener(MouseEvent.DOUBLE_CLICK, map_mouseDoubleClickHandler);
# m_firstpoints.splice(0);
# this.dispatchEvent(new DrawEvent("drawEnd", full_polygon_graphic));
# }
#
# /**
# *这个是贝塞尔曲线算法函数用于画军标
# *
# */
# private function drawBezierCurve():void
# {
# //主要算法思想是：由中轴线的两点确定一条直线，做直线的垂线，并取垂线上一定距离的点，作成上边曲线和下边曲线
# if ((m_gbjGeometry.paths != null) && (m_gbjGeometry.paths.length > 0))
# {
# m_gbjGeometry.removePath(0);
# }
# //判断点击点的季偶性,得到军标的多边形
# var jishu:Boolean=true;
# if (m_firstpoints.length % 2 == 0)
# {
# jishu=false;
# }
# clogger.logger.info("你点击的个数是不是奇数:"+jishu);
# var curvepoints:Array=getzz_geometry(m_firstpoints, jishu);
#
# var dgbj_geometry:Array=getdbx_geometry(curvepoints);
# full_gbjpolygon=new Polygon(dgbj_geometry);
# }
# /**
# * 这个函数就是用来求中轴线的，中轴线上的所有点
# * @param clickarray
# * @param jishu
# * @return
# *
# */
# private function getzz_geometry(clickarray:Array, jishu:Boolean):Array
# {
# //首先定义中轴曲线的点坐标
# var curvepoints:Array=new Array();
# //数组长度
# var array_length:Number=clickarray.length;
# if (jishu)
# {
# clogger.logger.info("你点击的次数是奇数个：并且他大于等于三，是：" + clickarray.length + "个");
# for (var i:int=0; i < clickarray.length - 2; i=i + 2)
# {
# for (var j:Number=0; j <= 1; j=j + 0.1)
# {
# if (i != 0 && j == 0)
# continue;
# var pos_x:Number=Math.pow((1 - j), 2) * clickarray.x + 2 * j * (1 - j) * clickarray[i + 1].x + Math.pow(j, 2) * clickarray[i + 2].x;
# var pos_y:Number=Math.pow((1 - j), 2) * clickarray.y + 2 * j * (1 - j) * clickarray[i + 1].y + Math.pow(j, 2) * clickarray[i + 2].y;
# var m_point:MapPoint=new MapPoint(pos_x, pos_y);
# curvepoints.push(m_point);
# }
# }
# }
# //下面的是偶数时后,前面那些点还是用三个点来确定，后面四个点用三次贝塞尔曲线来搞定。
# if (!jishu)
# {
# //判断点击的点是不是大于6个，如果是六个的话，首先是先用二次贝塞尔曲线算出前三个来。
# if (clickarray.length >= 6)
# {
# clogger.logger.info("你点击的次数是偶数个：并且他大于等于6，是：" + clickarray.length + "个");
# for (var i:int=0; i < clickarray.length - 5; i=i + 2)
# {
# for (var j:Number=0; j <= 1; j=j + 0.1)
# {
# if (i != 0 && j == 0)
# continue;
# var pos_x:Number=Math.pow((1 - j), 2) * clickarray.x + 2 * j * (1 - j) * clickarray[i + 1].x + Math.pow(j, 2) * clickarray[i + 2].x;
# var pos_y:Number=Math.pow((1 - j), 2) * clickarray.y + 2 * j * (1 - j) * clickarray[i + 1].y + Math.pow(j, 2) * clickarray[i + 2].y;
# var m_point:MapPoint=new MapPoint(pos_x, pos_y);
# //中轴线的点数
# curvepoints.push(m_point);
# }
# }
# //这最后四个点用三次贝塞尔曲线来确定
# var p_1:MapPoint=clickarray[array_length - 4];
# var p_2:MapPoint=clickarray[array_length - 3];
# var p_3:MapPoint=clickarray[array_length - 2];
# var p_4:MapPoint=clickarray[array_length - 1];
# for (var k:Number=0; k < 1; k=k + 0.1)
# {
# if (k == 0)
# continue;
# var pos_x:Number=p_1.x * Math.pow((1 - k), 3) + 3 * p_2.x * k * Math.pow((1 - k), 2) + 3 * p_3.x * Math.pow(k, 2) * (1 - k) + p_4.x * Math.pow(k, 3);
# var pos_y:Number=p_1.y * Math.pow((1 - k), 3) + 3 * p_2.y * k * Math.pow((1 - k), 2) + 3 * p_3.y * Math.pow(k, 2) * (1 - k) + p_4.y * Math.pow(k, 3);
# var m_point:MapPoint=new MapPoint(pos_x, pos_y);
# //中心轴的添加
# curvepoints.push(m_point);
# }
# }
# //如果仅仅就四个点的话，下面是求只有四个点的公式
# else
# {
# clogger.logger.info("你点击的次数是4个，他是：" + clickarray.length + "个");
# var p_1:MapPoint=clickarray[0];
# var p_2:MapPoint=clickarray[1];
# var p_3:MapPoint=clickarray[2];
# var p_4:MapPoint=clickarray[3];
# for (var k:Number=0; k < 1; k=k + 0.1)
# {
# var pos_x:Number=p_1.x * Math.pow((1 - k), 3) + 3 * p_2.x * k * Math.pow((1 - k), 2) + 3 * p_3.x * Math.pow(k, 2) * (1 - k) + p_4.x * Math.pow(k, 3);
# var pos_y:Number=p_1.y * Math.pow((1 - k), 3) + 3 * p_2.y * k * Math.pow((1 - k), 2) + 3 * p_3.y * Math.pow(k, 2) * (1 - k) + p_4.y * Math.pow(k, 3);
# var m_point:MapPoint=new MapPoint(pos_x, pos_y);
# //中心轴的添加
# curvepoints.push(m_point);
# }
# }
# }
# clogger.logger.info("这个中轴线上的所有的点的个数是：" + curvepoints.length);
# return curvepoints;
# }
#
# /**
# * 这个函数是用来求多边行的各个点的
# * 他利用的原理就是求垂线的距离
# * @return
# *
# */
# private function getdbx_geometry(curvepoints:Array):Array
# {
# //定义上边曲线的点坐标数组(当确定军标多边形的时候我是从这个数组开始的)
# var topcurepoints:Array=new Array();
# //定义下边曲线的点坐标数组
# var bottomcurepoints:Array=new Array();
# //定义左上测的直线
# var left_top_points:Array=new Array();
# //定义左下侧的直线
# var left_bottom_points:Array=new Array();
# //定义右上角边的数组
# var right_top_points:Array=new Array();
# //定义中轴线离上下两边的距离
# var dis:Number=(8 - map.level) * (8 - map.level) * 40;
# //大的框架肯定是从0--1
# var c_length:Number=curvepoints.length;
# for (var u:Number=0; u < curvepoints.length; u++)
# {
# if (u == 0)
# {
# continue;
# }
# else
# {
# var m_point:MapPoint=curvepoints;
# var pos_x:Number=m_point.x;
# var pos_y:Number=m_point.y;
# //先求上一点的坐标
# var pre_point:MapPoint=curvepoints[u - 1];
# //进行计算取的上下边的点
# var pre_pos_x:Number=pre_point.x;
# var pre_pos_y:Number=pre_point.y;
# var slope:Number=(pos_y - pre_pos_y) / (pos_x - pre_pos_x);
# //上边点确定
# var bb:Number=dis * (1 - u / c_length * 0.9);
# var cos_number:Number=Math.cos(Math.atan(slope) - Math.PI / 2);
# var sin_number:Number=Math.sin(Math.atan(slope) - Math.PI / 2);
# var top_pos_x:Number=0.0;
# var top_pos_y:Number=0.0;
# //下面分四种情况画线。
# if (pre_pos_x <= pos_x && pre_pos_y <= pos_y)
# {
# top_pos_x=pre_pos_x - ((bb * cos_number) < 0 ? (-bb * cos_number) : (bb * cos_number));
# top_pos_y=pre_pos_y + ((bb * sin_number) < 0 ? (-bb * sin_number) : (bb * sin_number));
# }
# else if (pre_pos_x <= pos_x && pre_pos_y > pos_y)
# {
# top_pos_x=pre_pos_x + ((bb * cos_number) < 0 ? (-bb * cos_number) : (bb * cos_number));
# top_pos_y=pre_pos_y + ((bb * sin_number) < 0 ? (-bb * sin_number) : (bb * sin_number));
# }
# else if (pre_pos_x >= pos_x && pre_pos_y >= pos_y)
# {
# top_pos_x=pre_pos_x + ((bb * cos_number) < 0 ? (-bb * cos_number) : (bb * cos_number));
# top_pos_y=pre_pos_y - ((bb * sin_number) < 0 ? (-bb * sin_number) : (bb * sin_number));
# }
# else if (pre_pos_x >= pos_x && pre_pos_y <= pos_y)
# {
# top_pos_x=pre_pos_x - ((bb * cos_number) < 0 ? (-bb * cos_number) : (bb * cos_number));
# top_pos_y=pre_pos_y - ((bb * sin_number) < 0 ? (-bb * sin_number) : (bb * sin_number));
# }
# var top_point:MapPoint=new MapPoint(top_pos_x, top_pos_y);
# clogger.logger.info("上半部分是：" + top_pos_x + "yy:" + top_pos_y);
# topcurepoints.push(top_point);
# //下面来确定下边的曲线
# var bottom_pos_x:Number;
# var bottom_pos_y:Number;
# if (pre_pos_x <= pos_x && pre_pos_y <= pos_y)
# {
# bottom_pos_x=pre_pos_x + ((bb * cos_number) < 0 ? (-bb * cos_number) : (bb * cos_number));
# bottom_pos_y=pre_pos_y - ((bb * sin_number) < 0 ? (-bb * sin_number) : (bb * sin_number));
# }
# else if (pre_pos_x <= pos_x && pre_pos_y > pos_y)
# {
# bottom_pos_x=pre_pos_x - ((bb * cos_number) < 0 ? (-bb * cos_number) : (bb * cos_number));
# bottom_pos_y=pre_pos_y - ((bb * sin_number) < 0 ? (-bb * sin_number) : (bb * sin_number));
# }
# else if (pre_pos_x >= pos_x && pre_pos_y >= pos_y)
# {
# bottom_pos_x=pre_pos_x - ((bb * cos_number) < 0 ? (-bb * cos_number) : (bb * cos_number));
# bottom_pos_y=pre_pos_y + ((bb * sin_number) < 0 ? (-bb * sin_number) : (bb * sin_number));
# }
# else if (pre_pos_x >= pos_x && pre_pos_y <= pos_y)
# {
# bottom_pos_x=pre_pos_x + ((bb * cos_number) < 0 ? (-bb * cos_number) : (bb * cos_number));
# bottom_pos_y=pre_pos_y + ((bb * sin_number) < 0 ? (-bb * sin_number) : (bb * sin_number));
# }
# var bottom_point:MapPoint=new MapPoint(bottom_pos_x, bottom_pos_y);
# bottomcurepoints.push(bottom_point);
# }
# }
# /*
# **下面是添加军标箭头的程序,因为现在已经得到上下边界的曲线了。
# **
# */
# var end_curvepoint:MapPoint=curvepoints[curvepoints.length - 1];
# var end_top_point:MapPoint=topcurepoints[topcurepoints.length - 1];
# var end_top_point2:MapPoint=topcurepoints[topcurepoints.length - 2];
# //求箭头上方的点
# var x2:Number=end_curvepoint.x;
# var y2:Number=end_curvepoint.y;
# var pos_x:Number=end_top_point.x;
# var pos_y:Number=end_top_point.y;
# var pre_pos_x:Number=end_top_point2.x;
# var pre_pos_y:Number=end_top_point2.y;
# var end_slope:Number=(pre_pos_y - pos_y) / (pre_pos_x - pos_x);
# var b:Number=dis;
# var end_point_x:Number;
# var end_point_y:Number;
# var cos_number:Number=Math.cos(Math.atan(end_slope) - Math.PI / 2);
# var sin_number:Number=Math.sin(Math.atan(end_slope) - Math.PI / 2);
# //下面分四种情况画线。
# if (pre_pos_x <= pos_x && pre_pos_y <= pos_y)
# {
# end_point_x=pre_pos_x - ((b * cos_number) < 0 ? (-b * cos_number) : (b * cos_number));
# end_point_y=pre_pos_y + ((b * sin_number) < 0 ? (-b * sin_number) : (b * sin_number));
# }
# else if (pre_pos_x <= pos_x && pre_pos_y > pos_y)
# {
# end_point_x=pre_pos_x + ((b * cos_number) < 0 ? (-b * cos_number) : (b * cos_number));
# end_point_y=pre_pos_y + ((b * sin_number) < 0 ? (-b * sin_number) : (b * sin_number));
# }
# else if (pre_pos_x >= pos_x && pre_pos_y >= pos_y)
# {
# end_point_x=pre_pos_x + ((b * cos_number) < 0 ? (-b * cos_number) : (b * cos_number));
# end_point_y=pre_pos_y - ((b * sin_number) < 0 ? (-b * sin_number) : (b * sin_number));
# }
# else if (pre_pos_x >= pos_x && pre_pos_y <= pos_y)
# {
# end_point_x=pre_pos_x - ((b * cos_number) < 0 ? (-b * cos_number) : (b * cos_number));
# end_point_y=pre_pos_y - ((b * sin_number) < 0 ? (-b * sin_number) : (b * sin_number));
# }
# //创建第三个点，然后创建三角形
# clogger.logger.info("右上面的点的横坐标点x:" + end_point_x + "----------右上方点的纵坐标的y:" + end_point_y);
# //得到右上方的点
# var end_right_point:MapPoint=new MapPoint(end_point_x, end_point_y);
# topcurepoints.push(end_right_point);
# //最右边，箭头顶点的坐标是
# clogger.logger.info("顶点的横坐标是x:" + end_curvepoint.x + "---------顶点的纵坐标y:" + end_curvepoint.y);
# topcurepoints.push(end_curvepoint);
# //下边线
# var end_bottom_point:MapPoint=bottomcurepoints[bottomcurepoints.length - 1];
# var end_bottom_point2:MapPoint=bottomcurepoints[bottomcurepoints.length - 2];
# //求箭头下方向的点
# var bx1:Number=end_bottom_point.x;
# var by1:Number=end_bottom_point.y;
# var bx0:Number=end_bottom_point2.x;
# var by0:Number=end_bottom_point2.y;
# var bend_slope:Number=(by1 - by0) / (bx1 - bx0);
# var bend_point_x:Number;
# var bend_point_y:Number;
# var bend_cos_number:Number=Math.cos(Math.atan(bend_slope) - Math.PI / 2);
# var bend_sin_number:Number=Math.sin(Math.atan(bend_slope) - Math.PI / 2);
# if (bx0 <= bx1 && by0 <= by1)
# {
# bend_point_x=bx0 + ((b * bend_cos_number) < 0 ? (-b * bend_cos_number) : (b * bend_cos_number));
# bend_point_y=by0 - ((b * bend_sin_number) < 0 ? (-b * bend_sin_number) : (b * bend_sin_number));
# }
# else if (bx0 <= bx1 && by0 > by1)
# {
# bend_point_x=bx0 - ((b * bend_cos_number) < 0 ? (-b * bend_cos_number) : (b * bend_cos_number));
# bend_point_y=by0 - ((b * bend_sin_number) < 0 ? (-b * bend_sin_number) : (b * bend_sin_number));
# }
# else if (bx0 >= bx1 && by0 >= by1)
# {
# bend_point_x=bx0 - ((b * bend_cos_number) < 0 ? (-b * bend_cos_number) : (b * bend_cos_number));
# bend_point_y=by0 + ((b * bend_sin_number) < 0 ? (-b * bend_sin_number) : (b * bend_sin_number));
# }
# else if (bx0 >= bx1 && by0 <= by1)
# {
# bend_point_x=bx0 + ((b * bend_cos_number) < 0 ? (-b * bend_cos_number) : (b * bend_cos_number));
# bend_point_y=by0 + ((b * bend_sin_number) < 0 ? (-b * bend_sin_number) : (b * bend_sin_number));
# }
# clogger.logger.info("下方的点的横坐标x为:" + bend_point_x + "-------下方的点的纵坐标y为:" + bend_point_y);
# //得到右下方的点
# var bend_right_point:MapPoint=new MapPoint(bend_point_x, bend_point_y);
# topcurepoints.push(bend_right_point);
# for (var k:Number=bottomcurepoints.length - 1; k >= 0; k--)
# {
# // 这个是下半部分
# clogger.logger.info("由此开始下半部分:" + bottomcurepoints[k].x + "yyyyy:" + bottomcurepoints[k].y);
# topcurepoints.push(bottomcurepoints[k]);
# }
# //添加尾部的部分,至此完成对军标多边行的算法，
# topcurepoints.push(curvepoints[1]);
# topcurepoints.push(topcurepoints[0]);
# clogger.logger.info("军标上的点的个数是" + topcurepoints.length);
# var rings:Array=new Array();
# rings.push(topcurepoints);
# return rings;
# }
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