Home Web Front-end HTML Tutorial canvas scratcher and brush

canvas scratcher and brush

Nov 04, 2016 pm 05:26 PM
canvas h5

舍不得买2块钱的刮刮乐,就只能写个类似的功能过过彩票瘾了!

布局

<div id="lottery" style="width:300px;height:500px;margin:10px;background-color:lightskyblue;border-radius:5px;float:left;">
         <div style="width:300px;height:100px;line-height:100px;text-align:center;font-size:33px;color:blueviolet;">NICK彩票</div>
         <div id="txt" style="width:300px;height:200px;font-size:40px;color:peachpuff;display:flex;justify-content:center;align-items:center;flex-direction:column;">
             <span>祝</span>
             <span>君</span>
             <span>中</span>
             <span>奖</span>
         </div>
         <div id="canvasArea" style="width:300px;height:200px;position:relative;">
             <div style="width:300px;height:200px;position:absolute;top:0;left:0;z-index:1;text-align:center;line-height:200px;font-weight:bold;font-size:56px;color:indianred;">一等奖</div>
             <canvas id="canvas" width="300px" height="200px" style="position:absolute;top:0;left:0;z-index:2;"></canvas>
         </div>
     </div>
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这段html要注意的地方有2个:

flex布局,将‘祝君中奖’垂直居中,目前还有兼容问题,不过看我们大前端的发展趋势,应该很快就能搞定了;

canvas和‘一等奖’div的z-index问题,将canvas的z-index设置较高,使其置于一等奖div上面。

设置canvas画布

var canvas = document.getElementById("canvas");

var context = canvas.getContext("2d");

绘制刮奖区域

context.fillStyle='#A9AB9D';
context.fillRect(10,10,280,180);
context.fillStyle='#000';
context.font='50px Arial';
context.fillText('刮奖区',75,115);

填充颜色;

绘制实心矩形;

设置字体颜色;

设置字体大小类型;

绘制实心字体。

以上都是canvas基础api,看w3c就ok了。

为了好看,我将‘祝君中奖’加个字体变色

        setInterval(function(){
            document.getElementById(&#39;txt&#39;).style.color = 
            document.getElementById(&#39;txt&#39;).style.color==&#39;
            peachpuff&#39; ? &#39;yellow&#39; : &#39;peachpuff&#39;;
        },500);
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刮奖功能函数

        var brush=function(){//刮奖
            context.clearRect(event.offsetX,event.offsetY,20,20);
        };
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为canvas元素onmousedown和onmouseup事件

复制代码

        canvas.onmousedown = function(){
            // 鼠标按下时 - 绑定鼠标跟随事件
            bindHandler(canvas,&#39;mousemove&#39;,brush,false);
        }
        canvas.onmouseup = function(){
            // 停止刮奖功能 - 解绑鼠标跟随事件
            removeHandler(canvas,"mousemove",brush,false);
        }
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复制代码

这里的事件绑定与解绑我上篇博文有封装,最后完整代码也有!


刮刮乐happy到底结束!最后附上完整代码,再看看效果吧!


demo二:画笔

布局

     <div style="width:300px;height:500px;margin:10px;border-radius:10px;overflow:hidden;float:right;">
         <canvas id="canvas2" width="300px" height="500px" style="background-color:lightblue;"></canvas>
     </div>
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设置canvas画布

        var canvas2 = document.getElementById("canvas2");
        var context2 = canvas2.getContext("2d");
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画笔功能函数

        var draw=function(){
            context2.fillRect(event.offsetX,event.offsetY,10,10);
        };
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为canvas元素onmousedown和onmouseup事件

        context2.font=&#39;20px Arial&#39;;
        context2.strokeText(&#39;NICK画笔&#39;,100,30);//写个头
        //1. 为canvas元素onmousedown和onmouseup事件
        canvas2.onmousedown = function(){
            // 启用画笔功能 - 绑定鼠标跟随事件
            bindHandler(canvas2,&#39;mousemove&#39;,draw,false);
        }
        canvas2.onmouseup = function(){
            // 停止画笔功能 - 解绑鼠标跟随事件
            removeHandler(canvas2,"mousemove",draw,false);
        }
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画图工具的画笔功能到底结束!


附上完整代码:



 
  Canvas lottery brush nick
  
 
 
 
<div id="lottery" style="width:300px;height:500px;margin:10px;background-color:lightskyblue;border-radius:5px;float:left;"> <div style="width:300px;height:100px;line-height:100px;text-align:center;font-size:33px;color:blueviolet;">NICK彩票</div> <div id="txt" style="width:300px;height:200px;font-size:40px;color:peachpuff;display:flex;justify-content:center;align-items:center;flex-direction:column;"> <span>祝</span> <span>君</span> <span>中</span> <span>奖</span> </div> <div id="canvasArea" style="width:300px;height:200px;position:relative;"> <div style="width:300px;height:200px;position:absolute;top:0;left:0;z-index:1;text-align:center;line-height:200px;font-weight:bold;font-size:56px;color:indianred;">一等奖</div> <canvas id="canvas" width="300px" height="200px" style="position:absolute;top:0;left:0;z-index:2;"></canvas> </div> </div> <div style="width:300px;height:500px;margin:10px;border-radius:10px;overflow:hidden;float:right;"> <canvas id="canvas2" width="300px" height="500px" style="background-color:lightblue;"></canvas> </div>

刮刮乐:鼠标按住不放,拖动开始刮奖!

画笔:鼠标按住不放,拖动画画!

<script> //插件方法封装区 ;(function(){ // 事件绑定 window.bindHandler = (function() { if (window.addEventListener) {// 标准浏览器 return function(elem, type, handler) { // elem:节点 type:事件类型 handler:事件处理函数 // 最后一个参数为true:在捕获阶段调用事件处理程序;为false:在冒泡阶段调用事件处理程序。注意:ie没有这个参数 elem.addEventListener(type, handler, false); } } else if (window.attachEvent) {// IE浏览器 return function(elem, type, handler) { elem.attachEvent("on" + type, handler); } } }()); // 事件解除 window.removeHandler = (function() { if (window.removeEventListener) {// 标准浏览器 return function(elem, type, handler) { elem.removeEventListener(type, handler, false); } } else if (window.detachEvent) {// IE浏览器 return function(elem, type, handler) { elem.detachEvent("on" + type, handler); } } }()); }()); //命名区 var canvas = document.getElementById("canvas"); var context = canvas.getContext("2d"); var canvas2 = document.getElementById(&quot;canvas2&quot;); var context2 = canvas2.getContext(&quot;2d&quot;); var brush=function(){//刮奖 context.clearRect(event.offsetX,event.offsetY,20,20); }; var draw=function(){//写字 context2.fillRect(event.offsetX,event.offsetY,10,10); }; //功能实现区 //刮刮乐 // 1. 绘制刮奖区域 context.fillStyle=&#39;#A9AB9D&#39;; context.fillRect(10,10,280,180); context.fillStyle=&#39;#000&#39;; context.font=&#39;50px Arial&#39;; context.fillText(&#39;刮奖区&#39;,75,115); //字体变色 setInterval(function(){ document.getElementById(&#39;txt&#39;).style.color = document.getElementById(&#39;txt&#39;).style.color==&#39;peachpuff&#39; ? &#39;yellow&#39; : &#39;peachpuff&#39;; },500); //2. 为canvas元素onmousedown和onmouseup事件 canvas.onmousedown = function(){ // 鼠标按下时 - 绑定鼠标跟随事件 bindHandler(canvas,&amp;#39;mousemove&amp;#39;,brush,false); } canvas.onmouseup = function(){ // 停止刮奖功能 - 解绑鼠标跟随事件 removeHandler(canvas,&quot;mousemove&quot;,brush,false); } //画笔 context2.font=&amp;#39;20px Arial&amp;#39;; context2.strokeText(&amp;#39;NICK画笔&amp;#39;,100,30);//写个头 //1. 为canvas元素onmousedown和onmouseup事件 canvas2.onmousedown = function(){ // 启用画笔功能 - 绑定鼠标跟随事件 bindHandler(canvas2,&amp;#39;mousemove&amp;#39;,draw,false); } canvas2.onmouseup = function(){ // 停止画笔功能 - 解绑鼠标跟随事件 removeHandler(canvas2,&quot;mousemove&quot;,draw,false); } </script>
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