javascript简易画板开发

2019-11-20 08:41:39

字体：大中小

来源：转载

供稿：网友

本文实例为大家分享了制作javascript简易画板的方法，供大家参考，具体内容如下

html：

<body id="bodys"><span id="eraser">清除所有</span><span id="colorbtn">笔画颜色</span><input type="range" name="ram" id="ram" min="1" max="20" step="1" value="10"/><label id="ramnum">字体大小:10px</label><ul id="colorpanel"><li>黑色</li><li>红色</li><li>绿色</li><li>蓝色</li></ul></body>

CSS：

*{margin: 0;padding: 0; }.box_black{background-color: black;position: absolute;}.box_red{background-color: red;position: absolute;}.box_green{background-color: green;position: absolute;}.box_blue{background-color: blue;position: absolute;}#eraser{width: 80px;height: 50px;background-color: brown;display: inline-block;text-align: center;line-height: 50px;cursor: pointer;}#colorbtn{width: 80px;height: 50px;background-color: tomato;display: inline-block;text-align: center;line-height: 50px;cursor: pointer;}#colorpanel{width: 80px;height: 200px;list-style: none;margin-left: 88px;display: none;}#colorpanel>li{width: 80px;height: 50px;text-align: center;line-height: 50px;background-color: aquamarine;display: inline-block;cursor: pointer;}#colorpanel>li:hover{background-color: orange;}

javascript：

window.onload=function(){   //把类名存成一个数组 var classname=["box_black","box_red","box_green","box_blue"]; //默认类名为box_black var clsname=classname[0]; var oBody=document.getElementById("bodys"); var oDiv=oBody.getElementsByTagName("div"); var eraser=document.getElementById("eraser"); var colorbtn=document.getElementById("colorbtn"); var colorpanel=document.getElementById("colorpanel"); var ram=document.getElementById("ram"); var ramnum=document.getElementById("ramnum");   colorbtn.onmouseover=function(){   colorpanel.style.display="block";   }    colorbtn.onmouseout=function(){   colorpanel.style.display="none";   }    colorpanel.onmouseover=function(){    this.style.display="block";    }    colorpanel.onmouseout=function(){    this.style.display="none";    }    for(var i=0;i<colorpanel.children.length;i++){    colorpanel.children[i].index=i;    colorpanel.children[i].onclick=function(){    //鼠标点击li切换类名来改变样式    clsname=classname[this.index];    colorpanel.style.display="none";    }    }    //定义默认字体大小为10px    var WIDTH="10px";    var HEIGHT="10px";    //通过滑动range来改变字体大小    ram.onmousemove=function(){    WIDTH=HEIGHT=ram.value+"px";    ramnum.innerHTML="字体大小:"+WIDTH;    }    //鼠标点击屏幕，通过滑动鼠标不停创建div属性节点，并且给它设置样式document.onmousedown=function(){ document.onmousemove=function(event){ var oevent=event||window.event; var scrolltop=document.documentElement.scrollTop||document.body.scrollTop; var scrollleft=document.documentElement.scrollLeft||document.body.scrollLeft; var box=document.createElement("div");    box.className=clsname;    box.style.width=WIDTH;    box.style.height=HEIGHT;    oBody.appendChild(box);    box.style.left=scrollleft+oevent.clientX+"px";    box.style.top=scrolltop+oevent.clientY+"px";}}//当鼠标按键松开，注销鼠标滑动事件document.onmouseup=function(){document.onmousemove=null;}//当橡皮差按钮被点击，遍历所有div并且把它们一一从父节点里面移除eraser.onclick=function(){var oDiv=oBody.getElementsByTagName("div");for(var i=0;i<oDiv.length;i++){oBody.removeChild(oDiv[i]);}}//以下为取消按钮的冒泡事件，因为我们点击按钮是不能绘制div的eraser.onmousedown=function(event){var ievent=event||window.event;ievent.cancelBubble=true;}colorbtn.onmousedown=function(event){var ievent=event||window.event;ievent.cancelBubble=true;}colorpanel.onmousedown=function(event){var ievent=event||window.event;ievent.cancelBubble=true;}ram.onmousedown=function(event){var ievent=event||window.event;ievent.cancelBubble=true;}}}

这是基于javascript的事件基础写的，比较简易，其实还可以进一步进行优化。下面来看效果图。