修改img.src时涂层也会自动适应新图片的尺寸.
修改layer函数可更改涂层样式
以下是HTML源代码(已增加移动设备支持):
<script><br /> (function(bodyStyle) {<br /> bodyStyle.mozUserSelect = 'none';<br /> bodyStyle.webkitUserSelect = 'none';<br /> <br /> var img = new Image();<br /> var canvas = document.querySelector('canvas');<br /> canvas.style.backgroundColor='transparent';<br /> canvas.style.position = 'absolute';<br /> <br /> img.addEventListener('load', function(e) {<br /> var ctx;<br /> var w = img.width,<br /> h = img.height;<br /> var offsetX = canvas.offsetLeft,<br /> offsetY = canvas.offsetTop;<br /> var mousedown = false;<br /> <br /> function layer(ctx) {<br /> ctx.fillStyle = 'gray';<br /> ctx.fillRect(0, 0, w, h);<br /> }<br /> <br /> function eventDown(e){<br /> e.preventDefault();<br /> mousedown=true;<br /> }<br /> <br /> function eventUp(e){<br /> e.preventDefault();<br /> mousedown=false;<br /> }<br /> <br /> function eventMove(e){<br /> e.preventDefault();<br /> if(mousedown) {<br /> if(e.changedTouches){<br /> e=e.changedTouches[e.changedTouches.length-1];<br /> }<br /> var x = (e.clientX + document.body.scrollLeft || e.pageX) - offsetX || 0,<br /> y = (e.clientY + document.body.scrollTop || e.pageY) - offsetY || 0;<br /> with(ctx) {<br /> beginPath()<br /> arc(x, y, 5, 0, Math.PI * 2);<br /> fill();<br /> }<br /> }<br /> }<br /> <br /> canvas.width=w;<br /> canvas.height=h;<br /> canvas.style.backgroundImage='url('+img.src+')';<br /> ctx=canvas.getContext('2d');<br /> ctx.fillStyle='transparent';<br /> ctx.fillRect(0, 0, w, h);<br /> layer(ctx);<br /> <br /> ctx.globalCompositeOperation = 'destination-out';<br /> <br /> canvas.addEventListener('touchstart', eventDown);<br /> canvas.addEventListener('touchend', eventUp);<br /> canvas.addEventListener('touchmove', eventMove);<br /> canvas.addEventListener('mousedown', eventDown);<br /> canvas.addEventListener('mouseup', eventUp);<br /> canvas.addEventListener('mousemove', eventMove);<br /> });<br /> img.src = 'data:image/png;base64,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';<br /> })(document.body.style);<br /></script>
需要判断是否刮完时用这段代码替换原代码的eventUp事件处理函数:
e.preventDefault();
mousedown = false;
var data=ctx.getImageData(0,0,w,h).data;
for(var i=0,j=0;i
j++;
}
}
if(j alert('ok');
}
这段代码中的0.1是10%的意思,在涂层的面积小于等于10%时,就弹出窗口,表示刮完了,可以根据需求自行调整

HTML5 is a key technology for building modern web pages, providing many new elements and features. 1. HTML5 introduces semantic elements such as, , etc., which enhances web page structure and SEO. 2. Support multimedia elements and embed media without plug-ins. 3. Forms enhance new input types and verification properties, simplifying the verification process. 4. Offer offline and local storage functions to improve web page performance and user experience.

Best practices for H5 code include: 1. Use correct DOCTYPE declarations and character encoding; 2. Use semantic tags; 3. Reduce HTTP requests; 4. Use asynchronous loading; 5. Optimize images. These practices can improve the efficiency, maintainability and user experience of web pages.

Web standards and technologies have evolved from HTML4, CSS2 and simple JavaScript to date and have undergone significant developments. 1) HTML5 introduces APIs such as Canvas and WebStorage, which enhances the complexity and interactivity of web applications. 2) CSS3 adds animation and transition functions to make the page more effective. 3) JavaScript improves development efficiency and code readability through modern syntax of Node.js and ES6, such as arrow functions and classes. These changes have promoted the development of performance optimization and best practices of web applications.

H5 is not just the abbreviation of HTML5, it represents a wider modern web development technology ecosystem: 1. H5 includes HTML5, CSS3, JavaScript and related APIs and technologies; 2. It provides a richer, interactive and smooth user experience, and can run seamlessly on multiple devices; 3. Using the H5 technology stack, you can create responsive web pages and complex interactive functions.

H5 and HTML5 refer to the same thing, namely HTML5. HTML5 is the fifth version of HTML, bringing new features such as semantic tags, multimedia support, canvas and graphics, offline storage and local storage, improving the expressiveness and interactivity of web pages.

H5referstoHTML5,apivotaltechnologyinwebdevelopment.1)HTML5introducesnewelementsandAPIsforrich,dynamicwebapplications.2)Itsupportsmultimediawithoutplugins,enhancinguserexperienceacrossdevices.3)SemanticelementsimprovecontentstructureandSEO.4)H5'srespo

The tools and frameworks that need to be mastered in H5 development include Vue.js, React and Webpack. 1.Vue.js is suitable for building user interfaces and supports component development. 2.React optimizes page rendering through virtual DOM, suitable for complex applications. 3.Webpack is used for module packaging and optimize resource loading.

HTML5hassignificantlytransformedwebdevelopmentbyintroducingsemanticelements,enhancingmultimediasupport,andimprovingperformance.1)ItmadewebsitesmoreaccessibleandSEO-friendlywithsemanticelementslike,,and.2)HTML5introducednativeandtags,eliminatingthenee


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