怎么动态绘制一个带面积周长的矩形？

• 回答：

  动态拖放时的绘制事件：

  
  

  function DynWorldDrawMatrix( pCustomEntity, pWorldDraw, curPt) {
      //与用户交互在图面上提取一个点
      var vBasePt = pCustomEntity.GetPoint("BasePoint");
      //计算中心点位置
      var centerPt = mxOcx.NewPoint();
      {
          centerPt.x = curPt.x + (vBasePt.x - curPt.x) / 2;
          centerPt.y = curPt.y + (vBasePt.y - curPt.y) / 2;
      }
      //计算面积（取绝对值）
      var arec = Math.abs(vBasePt.x - curPt.x) * Math.abs(vBasePt.y - curPt.y);
      //计算周长
      var girth = 2 * (Math.abs(vBasePt.x - curPt.x) + Math.abs(vBasePt.y - curPt.y));
      //变换视区长度
      var dHeigth = mxOcx.ViewLongToDocCoord(15);
      //绘制一个单行文字
      //参数一为文字的位置的X坐标 ；参数二为文字的位置的Y坐标 ；参数三为文字内容字符串
      //参数四为文字高度；参数五为文字的旋转角度
      //参数六为文字的水平对齐方式,0=kTextLeft,1=kTextCenter,2=kTextRight
      //参数七文字的竖直对齐方式,1=kTextBottom,2=kTextVertMid,3=kTextTop
      pWorldDraw.DrawText(centerPt.x, centerPt.y, "面积：" + arec.toFixed(2), dHeigth, 0, 1, 1);
      pWorldDraw.DrawText(centerPt.x, centerPt.y, "周长：" + girth.toFixed(2), dHeigth, 0, 1, 3);
      //绘制一个直线
      //参数一直线的开始点x坐标，参数二直线的开始点y坐标，参数三直线的结束点x坐标，参数四直线的结束点y坐标
      pWorldDraw.DrawLine (vBasePt.x, vBasePt.y, vBasePt.x, curPt.y);
      pWorldDraw.DrawLine (vBasePt.x, curPt.y, curPt.x, curPt.y);
      pWorldDraw.DrawLine (curPt.x, curPt.y, curPt.x, vBasePt.y);
      pWorldDraw.DrawLine (curPt.x, vBasePt.y, vBasePt.x, vBasePt.y);
  }

  
  

  动态绘制矩形框：

  
  

  function DynDrawMatrix() {
      // 创建一个与用户交互取点的对象。
      var point1 = mxOcx.GetPoint(false,0,0,"\n 点取开始点:");
      if(point1 == null)
      {
          return;
      }
      var getSecondPt = mxOcx.NewComObject("IMxDrawUiPrPoint");
      getSecondPt.message = "第二点";
      getSecondPt.basePoint = point1;
      //不开启皮筋效果
      getSecondPt.setUseBasePt(false);
      //调用
      var spDrawData = getSecondPt.InitUserDraw("TestDynDrawMatrix");
      // 设置动态绘制参数.
      spDrawData.SetPoint("BasePoint", point1);
      // 开始取第二个点。
      if (getSecondPt.go() != 1)
          return;
      var ret = spDrawData.Draw();
  }