最近项目正好用到，分享一下。无需任何本地支持即可浏览器（支持HTML5）在线预览pdf文档。
1.首先下载相关包：https://github.com/mozilla/pdf.js/archive/gh-pages.zip
2. 解压后的目录：
把整个目录拷贝到网站的任何js公共目录下。
3.使用pdf.js自带的预览界面viewer.html,传入pdf文件的url即可。把pdf拷贝到上图web目录下，
页面局部显示直接：
<iframe ref="iframe" :src=pdfUrl style=" width:90%; height:100%;" frameborder="0"></iframe>
如果想弹窗：直接a标签，调用 window.open(url,'PDF','width:00%;height:100%;');
4.加载动态水印，修改viewer.js 和 viewer.css；
viewer.css添加：
.cover {
position: absolute;
top: 0;
overflow: hidden
}
viewer.js (约7180行)添加：
var _this = this;
if (this.renderingState !== _pdf_rendering_queue.RenderingStates.INITIAL) {
console.error('Must be in new state before drawing');
this.reset();
}
if (!this.pdfPage) {
this.renderingState = _pdf_rendering_queue.RenderingStates.FINISHED;
return Promise.reject(new Error('Page is not loaded'));
}
this.renderingState = _pdf_rendering_queue.RenderingStates.RUNNING;
var pdfPage = this.pdfPage;
var div = this.div;
var canvasWrapper = document.createElement('div');
canvasWrapper.style.width = div.style.width;
canvasWrapper.style.height = div.style.height;
canvasWrapper.classList.add('canvasWrapper');
if (this.annotationLayer && this.annotationLayer.div) {
div.insertBefore(canvasWrapper, this.annotationLayer.div);
} else {
div.appendChild(canvasWrapper);
}
var textLayer = null;
if (this.textLayerMode !== _ui_utils.TextLayerMode.DISABLE && this.textLayerFactory) {
var textLayerDiv = document.createElement('div');
textLayerDiv.className = 'textLayer';
textLayerDiv.style.width = canvasWrapper.style.width;
textLayerDiv.style.height = canvasWrapper.style.height;
//开始添加
var cover = document.createElement('div');
cover.className = "cover";
//debugger;
var defaultSettings = {
watermark_txt: window.parent.waterMark,
watermark_x: 0,//水印起始位置x轴坐标
watermark_y: 0,//水印起始位置Y轴坐标
watermark_rows: 10,//水印行数
watermark_cols: 10,//水印列数
watermark_x_space: 60,//水印x轴间隔
watermark_y_space: 30,//水印y轴间隔
watermark_color: '#DED3AA',//水印字体颜色
watermark_alpha: 0.3,//水印透明度
watermark_fontsize: '30px',//水印字体大小
watermark_font: '微软雅黑',//水印字体
watermark_width: 240,//水印宽度
watermark_height: 180,//水印长度
watermark_angle: 35//水印倾斜度数
};
var oTemp = document.createDocumentFragment();
//获取页面最大宽度
var page_width = parseInt(canvasWrapper.style.width);
//获取页面最大长度
var page_height = parseInt(canvasWrapper.style.height);
////获取页面最大宽度
//var page_width = Math.max(document.body.scrollWidth, document.body.clientWidth);
////获取页面最大长度
//var page_height = Math.max(document.body.scrollHeight, document.body.clientHeight);
//如果将水印列数设置为0，或水印列数设置过大，超过页面最大宽度，则重新计算水印列数和水印x轴间隔
if (defaultSettings.watermark_cols == 0 || (parseInt(defaultSettings.watermark_x + defaultSettings.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1)) > page_width)) {
defaultSettings.watermark_cols = parseInt((page_width - defaultSettings.watermark_x + defaultSettings.watermark_x_space) / (defaultSettings.watermark_width + defaultSettings.watermark_x_space));
defaultSettings.watermark_x_space = parseInt((page_width - defaultSettings.watermark_x - defaultSettings.watermark_width * defaultSettings.watermark_cols) / (defaultSettings.watermark_cols - 1));
}
//如果将水印行数设置为0，或水印行数设置过大，超过页面最大长度，则重新计算水印行数和水印y轴间隔
if (defaultSettings.watermark_rows == 0 || (parseInt(defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1)) > page_height)) {
defaultSettings.watermark_rows = parseInt((defaultSettings.watermark_y_space + page_height - defaultSettings.watermark_y) / (defaultSettings.watermark_height + defaultSettings.watermark_y_space));
defaultSettings.watermark_y_space = parseInt(((page_height - defaultSettings.watermark_y) - defaultSettings.watermark_height * defaultSettings.watermark_rows) / (defaultSettings.watermark_rows - 1));
}
var x;
var y;
for (var i = 0; i < defaultSettings.watermark_rows; i++) {
y = defaultSettings.watermark_y + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i;
var cols = defaultSettings.watermark_cols;
if (i % 2 != 0) { cols = defaultSettings.watermark_cols - 1; }
for (var j = 0; j < cols; j++) {
x = defaultSettings.watermark_x + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j;
var mask_div = document.createElement('div');
mask_div.id = 'mask_div' + i + j;
mask_div.className = 'mask_div';
mask_div.appendChild(document.createTextNode(defaultSettings.watermark_txt));
//设置水印div倾斜显示
mask_div.style.webkitTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.MozTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.msTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.OTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.transform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
mask_div.style.visibility = "";
mask_div.style.position = "absolute";
//奇偶行错开，这样水印就不对齐，显的不呆板
if (i % 2 != 0) {
mask_div.style.left = x + 100 + 'px';
} else {
mask_div.style.left = x + 'px';
}
mask_div.style.top = y + 'px';
mask_div.style.overflow = "hidden";
mask_div.style.opacity = defaultSettings.watermark_alpha;
mask_div.style.fontSize = defaultSettings.watermark_fontsize;
mask_div.style.fontFamily = defaultSettings.watermark_font;
mask_div.style.color = defaultSettings.watermark_color;
mask_div.style.textAlign = "center";
mask_div.style.width = canvasWrapper.style.width + 'px';
mask_div.style.height = canvasWrapper.style.height + 'px';
mask_div.style.display = "block";
oTemp.appendChild(mask_div);
}
}
cover.appendChild(oTemp);
//结束
if (this.annotationLayer && this.annotationLayer.div) {
div.insertBefore(textLayerDiv, this.annotationLayer.div);
//添加
div.appendChild(cover);
//结束
} else {
div.appendChild(textLayerDiv);
//添加
div.appendChild(cover);
//结束
}
textLayer = this.textLayerFactory.createTextLayerBuilder(textLayerDiv, this.id - 1, this.viewport, this.textLayerMode === _ui_utils.TextLayerMode.ENABLE_ENHANCE);
//添加
var cover = document.getElementsByClassName('cover');
for (var i = 0, len = cover.length; i < len; i++) {
cover[i].style.width = canvasWrapper.style.width;
cover[i].style.height = canvasWrapper.style.height;
}
}
this.textLayer = textLayer;
var renderContinueCallback = null;
其中window.parent.waterMark,就是动态水印要显示的文本。
在pdf预览的页面js添加： waterMark = "Hello,水门";
----亲昵的陌生人，我们总是一直在路上。next plane home~ bye.
