层的拖动 且 不超过边界

onmousedown="layerMousedown();" onmousemove="layerMousemove();" onmouseup="layerMouseup();" var layerMoveFlag = false;var x1= 0;var y1= 0;function layerMousedown(){layerMoveFlag=true;var layerMsg = document.getElementById("layerMsg");x1=window.event.clientX-layerMsg.offsetLeft;y1=window.event.clientY-layerMsg.offsetTop;}function layerMousemove(){if(layerMoveFlag){var mydiv = document.getElementById("layerMsg");mydiv.setCapture();var X=window.event.clientX;var Y=window.event.clientY;if(Y-y1<0){Y=y1}if(X-x1<0){X=x1;}if((X-x1)>(winWidth-419)){X=winWidth-(419-x1);}if((Y-y1)>(winHeight-205)){Y=winHeight-(205-y1);}mydiv.style.left=X-x1+"px";mydiv.style.top =Y-y1+"px";}}function layerMouseup(){layerMoveFlag=false;document.getElementById("layerMsg").releaseCapture();}

 

jsp中层的调动：