React Native自定义View解析Emoji

前端之家收集整理的这篇文章主要介绍了React Native自定义View解析Emoji前端之家小编觉得挺不错的,现在分享给大家,也给大家做个参考。
 
 

一、需求准备

在react native的类中实现可以解析多种字符格式的内容并放入到指定文本中。效果图如下:

emoji_example_1

二、Emoji封装

将需要对应好的Emoji表情图片放到指定文件夹,然后写一个公共的Const.js封装成一个对象,实现变量与图片资源的关系映射:

export const emojiReflection = { // emoji表情对应关系 "[微笑]": require('../emojiImage/emoji_1.png'),"[呲牙]": require('../emojiImage/emoji_2.png'),"[偷笑]": require('../emojiImage/emoji_3.png'),…… } export const emojiReflection = { // emoji表情对应关系 "[微笑]": require('../emojiImage/emoji_1.png'),…… }

三、生命周期方法的简单处理

这里只针对于子文本的展示,实际效果是将该文本放到一个ListView的item中,其功能实现无大差异,只需在外层包一个ListView即可。所以这里只需将这个文本放入一个Text标签中。
  这里加入了对文本高度的判断,超过了4行只展示4行,并展示出“更多”按钮,由于设置了行高为20,只需在onLayout( )方法中对高度设置监听处理即可。

return ( <View> <Text key={'textMore'} style={{ lineHeight: 20,maxHeight: this.state.rowHeight }} onLayout={this.state.textState == 1 ? (e) => { let {x,y,width,height} = e.nativeEvent.layout; if (Math.ceil(height / 20) > 4 && this.state.textState == 1) { this.setState({ textState: 2,rowHeight: 80 }); } else { this.setState({ rowHeight: height }); } } : null}> {this.state.Views} </Text> {showMore} </View> ); return ( <View> <Text key={'textMore'} style={{ lineHeight: 20,rowHeight: 80 }); } else { this.setState({ rowHeight: height }); } } : null}> {this.state.Views} </Text> {showMore} </View> );

其中,这里的this.state.Views是一个数组,用于存放截取处理后的各个子View。可在constructor( )或componentWillMount( )方法中定义:

constructor() { super(); this.state = { rowHeight: 10000,textState: 1,Views: [],} } constructor() { super(); this.state = { rowHeight: 10000,} }

这里,在componentWillMount( )方法中接收指定字符串textContent(当然你完全可以自定义一个你想要的String):

componentWillMount() { let textContent = this.props.textContent; this.matchContentString(textContent); } componentWillMount() { let textContent = this.props.textContent; this.matchContentString(textContent); }

匹配的逻辑与思路

这里用到的是正则匹配的方法,先定义出三种匹配规则,即匹配[微笑]格式的emoji表情、匹配@...格式的文本、匹配http://www.baidu.com 格式的网址。
  先使用正则定义好匹配方法

let emojiReg = '\\[[^\\]]+\\]'; let nameReg = '@([^\\s@]+)'; let httpReg = '((https://|http://|www\.|ftp://)[A-Za-z0-9\._\?%&;:+\-=/#]*)'; let emojiAt = new RegExp(emojiReg); let nameAt = new RegExp(nameReg); let httpAt = new RegExp(httpReg); let emojiReg = '\\[[^\\]]+\\]'; let nameReg = '@([^\\s@]+)'; let httpReg = '((https://|http://|www\.|ftp://)[A-Za-z0-9\._\?%&;:+\-=/#]*)'; let emojiAt = new RegExp(emojiReg); let nameAt = new RegExp(nameReg); let httpAt = new RegExp(httpReg);

然后开始写一个方法,实现自己的思路:将一个字符串按三种匹配规则匹配,得到3个index,取最小者,将这个字符串拆分成三部分,即0-index,index,index-end。然后0-index部分直接返回一个文本,index部分再分别处理,然后将最后的index-end部分实现递归,直到最终的index为-1,即只剩下纯文本为止。

matchContentString(textContent) { // 匹配得到3个index并放入数组中 let emojiIndex = textContent.search(emojiAt); let nameIndex = textContent.search(nameAt); let httpIndex = textContent.search(httpAt); let checkIndexArray = []; // 若匹配不到,则直接返回一个全文本 if (emojiIndex === -1 && nameIndex === -1 && httpIndex === -1) { let emptyTextView = (<Text key ={'emptyTextView'+(Math.random()*100)}>{textContent}</Text>); this.state.Views.push(emptyTextView); } else { if (emojiIndex !== -1) checkIndexArray.push(emojiIndex); if (nameIndex !== -1) checkIndexArray.push(nameIndex); if (httpIndex !== -1) checkIndexArray.push(httpIndex); // 取index最小者 let minIndex = Math.min.apply(Math,checkIndexArray); // 将0-index部分返回文本 let firstTextView = (<Text key ={'firstTextView'+(Math.random()*100)}>{textContent.substring(0,minIndex)}</Text>); this.state.Views.push(firstTextView); // 将index部分作分别处理 switch (minIndex) { case emojiIndex: this.matchEmojiString(textContent.substring(minIndex)); break; case nameIndex: this.matchNameString(this.props.ats,this.props.atDeparts,textContent.substring(minIndex)); break; case httpIndex: this.matchHttpString(textContent.substring(minIndex)); break; default: break; } } } matchContentString(textContent) { // 匹配得到3个index并放入数组中 let emojiIndex = textContent.search(emojiAt); let nameIndex = textContent.search(nameAt); let httpIndex = textContent.search(httpAt); let checkIndexArray = []; // 若匹配不到,则直接返回一个全文本 if (emojiIndex === -1 && nameIndex === -1 && httpIndex === -1) { let emptyTextView = (<Text key ={'emptyTextView'+(Math.random()*100)}>{textContent}</Text>); this.state.Views.push(emptyTextView); } else { if (emojiIndex !== -1) checkIndexArray.push(emojiIndex); if (nameIndex !== -1) checkIndexArray.push(nameIndex); if (httpIndex !== -1) checkIndexArray.push(httpIndex); // 取index最小者 let minIndex = Math.min.apply(Math,textContent.substring(minIndex)); break; case httpIndex: this.matchHttpString(textContent.substring(minIndex)); break; default: break; } } }

如上代码,可看到,每执行一次比较处理index的思路就会将原文本拆分成三部分,然后再分别处理。这样的定位index会比较明确。下面就再实现一下具体的三种处理方式:

【处理带emoji表情的】

matchEmojiString(emojiStr) { let castStr = emojiStr.match(emojiAt); let emojiLength = castStr[0].length; let imageView = (<Image key={emojiStr} style={{ width: 15,height: 14 }} source={emojiReflection[castStr]} />); this.state.Views.push(imageView); this.matchContentString(emojiStr.substring(emojiLength)); } matchEmojiString(emojiStr) { let castStr = emojiStr.match(emojiAt); let emojiLength = castStr[0].length; let imageView = (<Image key={emojiStr} style={{ width: 15,height: 14 }} source={emojiReflection[castStr]} />); this.state.Views.push(imageView); this.matchContentString(emojiStr.substring(emojiLength)); } 

【处理带@...文本的】

matchNameString(ats,atDeparts,nameStr) { let castStr = nameStr.match(nameAt); let nameString = castStr[0]; let atUser = null; let atMyDeparts = null; if (ats && ats.length > 0) { atUser = ats[0]; } if (atUser == null && atDeparts && atDeparts.length > 0) { atMyDeparts = atDeparts[0]; } let nameView = (<CustomTextView key={'name' + nameStr} textContent={nameString} contentType={'name'} atUser={atUser} atDeparts={atMyDeparts} />); this.state.Views.push(nameView); this.matchContentString(nameStr.substring(nameString.length)); } matchNameString(ats,nameStr) { let castStr = nameStr.match(nameAt); let nameString = castStr[0]; let atUser = null; let atMyDeparts = null; if (ats && ats.length > 0) { atUser = ats[0]; } if (atUser == null && atDeparts && atDeparts.length > 0) { atMyDeparts = atDeparts[0]; } let nameView = (<CustomTextView key={'name' + nameStr} textContent={nameString} contentType={'name'} atUser={atUser} atDeparts={atMyDeparts} />); this.state.Views.push(nameView); this.matchContentString(nameStr.substring(nameString.length)); } 

【处理带http:...网址的】

matchHttpString(httpStr) { let castStr = httpStr.match(httpAt); let httpString = castStr[0]; let httpView = (<CustomTextView key={'http'+httpString} textContent={httpString} contentType={'http'} />); this.state.Views.push(httpView); this.matchContentString(httpStr.substring(httpString.length)); } matchHttpString(httpStr) { let castStr = httpStr.match(httpAt); let httpString = castStr[0]; let httpView = (<CustomTextView key={'http'+httpString} textContent={httpString} contentType={'http'} />); this.state.Views.push(httpView); this.matchContentString(httpStr.substring(httpString.length)); } 

其中CustomTextView只是一个简单的自定义View,只实现如跳转链接,改变字体颜色等功能,完全可以自定义,在这里就不贴代码了。
  最终,一个满足三种匹配的自定义View就实现啦,看下效果咯~

原文链接:https://www.f2er.com/react/302073.html

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