安装网站源码,个体营业执照网上年报,2019年云南建设银行招聘网站,网页制作的工具有哪些实现样式 需求
实现PDF上传预览#xff0c;并且不能下载 第一次实现#xff1a;用vue-pdf#xff0c;将上传的文件用base64传给前端展示 问题#xff1a; 水印第一次加载有后面又没有了。当上传大的pdf文件后#xff0c;前端获取和渲染又长又慢#xff0c;甚至不能用 修…实现样式 需求
实现PDF上传预览并且不能下载 第一次实现用vue-pdf将上传的文件用base64传给前端展示 问题 水印第一次加载有后面又没有了。当上传大的pdf文件后前端获取和渲染又长又慢甚至不能用 修改实现模式
前端上传PDF后端将PDF转化成一页一页的图片前端根据page去获取一页一页的PDF图片类似于百度文库
实现思路
配合后端实现思路
获取全部页数先把侧边栏的元素画出来占个位置获取已经看到的页数没有默认1渲染上次看到的页数同时侧边栏滚动到相同的index位置通过监听元素是否进入视口去获取base64图片已经获取回来的图片不再去请求
主要重点难点是侧边栏懒加载、定位、等比例展示图片 div classpdf-viewerdiv classpdf-maincanvas idpdf-view/canvas/divdiv classpdf-list :class{ collapse: collapse }divclasspdf-item:class{ active: currentPage index }v-forindex in pageTotalNum:keyindexclickchangePage(index):data-indexindeximg :srcimgList[index - 1] alt //div/div/divscript
let observer null;
export default {name: PDFView,data() {return {currentPage: 1, //当前页数pageTotalNum: 1, //总页数imgList: [], //base64图片列表updateTimer: null};},watch: {/*** description 监听当前页变化 滚动列表到顶部*/currentPage() {this.$nextTick(() {const activeEl document.querySelector(.pdf-list .active);if (activeEl) {document.querySelector(.pdf-list).scrollTo({top: activeEl.offsetTop - 20,behavior: smooth,});// 解决进来会请求当前页数 前面所有图片setTimeout(() {if (observer) {observer.disconnect();}this.isEnter();}, 500);}// 切换页面 将查看区域滚动到最上面const mainEl document.querySelector(.pdf-main);mainEl.scrollTo({top: 0,});});},},mounted() {this.getPageTotal();},beforeDestroy() {if (observer) {observer.disconnect();}},methods: {/*** description 获取pdf总页数*/getPageTotal() {const params {id: this.$route.query.id,};apiGetViewPdfPageTotal(params).then((response) {this.pageTotalNum response.data;this.updateStudy(true);});},/*** description 切换当前页*/changePage(index) {this.currentPage index;this.updateStudy();if (this.imgList[index - 1]) {this.drawImage(this.imgList[index - 1]);} else {this.getPdf();}},/*** description 上一页*/prePage() {let page this.currentPage;if (page ! 1) {page page 1 ? page - 1 : this.pageTotalNum;this.currentPage page;this.updateStudy();if (this.imgList[page - 1]) {this.drawImage(this.imgList[page - 1]);} else {this.getPdf();}}},/*** description 下一页*/nextPage() {let page this.currentPage;if (page ! this.pageTotalNum) {page page this.pageTotalNum ? page 1 : 1;this.currentPage page;this.updateStudy();if (this.imgList[page - 1]) {this.drawImage(this.imgList[page - 1]);} else {this.getPdf();}}},/*** description 更新学习 flagtrue第一次进入*/updateStudy(flag false) {const params {courseId: this.$route.query.id,pageRate: this.currentPage,flag,totalPageRate: this.pageTotalNum,};apiUpdateStudy(params).then((response) {this.currentPage response.data.pageRate;if (flag) {this.updateTimer setInterval(() {this.updateStudy();}, 1000 * 10);}if (flag) {this.getPdf();// 解决第一页进来不请求的问题一页大概能展示4-5张if (this.currentPage 5) {this.isEnter();}}})},/*** description 查看资料*/getPdf() {const params {id: this.$route.query.id,page: this.currentPage,};apiGetPdf(params).then((response) {let base64 data:image/png;base64, response.data;this.drawImage(base64);});},/*** description 将base64图片 画到canvas上*/drawImage(base64) {const canvas document.getElementById(pdf-view);const context canvas.getContext(2d);const image new Image();image.src base64;image.onload () {const proportion image.width / image.height;// 获取style设置width:100% 的canvas宽度const canvasWidth canvas.offsetWidth;// 图片宽度与canvas宽度比例const canvasWidthProportion image.width / canvasWidth;// canvas宽度设置为宽度canvas.width image.width;// 根据图片比例和宽度比例计算出canvas高度canvas.height (canvasWidth / proportion) * canvasWidthProportion;context.drawImage(image, 0, 0);};},/*** description 监听元素进入视口*/isEnter() {observer new IntersectionObserver((entries) {entries.forEach((entry) {const target entry.target;const index target.dataset.index;if (entry.isIntersecting) {if (!this.imgList[index - 1]) {this.getImgList(index);}} else {// console.log(元素离开视口, index);}});});this.$nextTick(() {//将所有侧边栏的元素进行监听const els document.querySelectorAll(.pdf-item);Array.from(els).forEach((el) {observer.observe(el);});});},/*** description 滚动获取图片*/getImgList(index) {const params {id: this.$route.query.id,page: index,};apiGetPdf(params).then((response) {let base64 data:image/png;base64, response.data;this.imgList[index - 1] base64;// 解决请求回来页面没更新的问题this.$forceUpdate();});},},
};
/scriptstyle langscss scoped
.pdf-container {width: 100%;height: 100%;color: #999;
}
.pdf-viewer {width: 100%;height: calc(100vh - 50px - 30px - 60px - 6px);position: relative;display: flex;
}
.pdf-list {width: 240px;overflow-y: auto;display: flex;flex-direction: column;padding: 20px;background: #000;box-sizing: border-box;// transition: all 0.3s ease-in-out;border-left: 1px solid #999;::-webkit-scrollbar {width: 0px;}.pdf-item {height: 183px;min-height: 183px;display: inline-flex;justify-content: center;align-items: center;cursor: pointer;overflow: hidden;:hover {::v-deep img {transition: all 0.5s ease-in-out;transform: scale(1.1);}}.active {box-shadow: 0px 0px 0px 4px #e6a23c;}:not(:last-child) {margin-bottom: 10px;}img {pointer-events: none;width: 100%;// height: 100%;}}.collapse {width: 0;padding: 0;}
}
.pdf-main {flex: 1;// width: 100%;// height: 100%;overflow-y: auto;background: #000;position: relative;padding: 10px 0;::-webkit-scrollbar {width: 0px;}
}
.handle-btn {background: #000;display: flex;font-size: 12px;position: relative;height: 60px;padding: 0 6px;border-bottom: 1px solid #999;.right {width: 240px;display: flex;align-items: center;justify-content: flex-end;font-size: 32px;}.main {flex: 1;display: flex;align-items: center;justify-content: center;font-size: 32px;margin-left: 250px;.pagination {display: flex;align-items: center;margin: 0 10px;.pagination-info {font-size: 14px;margin: 0 8px;}}.zoom {display: flex;align-items: center;margin: 0 10px;.scale {font-size: 14px;margin: 0 8px;}}}.tips {color: #e6a23c;font-size: 12px;}.start-test {display: flex;align-items: center;}.time {position: absolute;left: 6px;top: 50%;transform: translateY(-50%); span {display: inline-block;margin-left: 10px;}}
}
i {cursor: pointer;:hover {color: #fff;}
}
#pdf-view {width: 100%;// height: 100%;padding: 10px;
}
/style
