PDF.js 预览添加水印

作者: 肆意木 | 来源:发表于2018-10-19 20:23 被阅读42次

    效果图:

    简书

    只需要在 viewer.js 和 viewer.css 里面修改即可

    viewer.js (约7180行):

                        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.textLayerFactory) {
                            var textLayerDiv = document.createElement('div');
                            textLayerDiv.className = 'textLayer';
                            textLayerDiv.style.width = canvasWrapper.style.width;
                            textLayerDiv.style.height = canvasWrapper.style.height;
       //从这里开始
                            var cover = document.createElement('div');
                            cover.className = "cover";
                            var defaultSettings = {
                                watermark_txt: "简书",
                                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: 30,//水印行数
                                watermark_cols: 100,//水印列数
                                watermark_x_space: 10,//水印x轴间隔
                                watermark_y_space: 10,//水印y轴间隔
                                watermark_color: 'red',//水印字体颜色
                                watermark_alpha: 0.3,//水印透明度
                                watermark_fontsize: '20px',//水印字体大小
                                watermark_font: '微软雅黑',//水印字体
                                watermark_width: 120,//水印宽度
                                watermark_height: 80,//水印长度
                                watermark_angle: 45//水印倾斜度数
                            };
                            var oTemp = document.createDocumentFragment();
    
                            //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;
                                for (var j = 0; j < defaultSettings.watermark_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);
    //这里结束
                            if (this.annotationLayer && this.annotationLayer.div) {
                                div.insertBefore(textLayerDiv, this.annotationLayer.div);
    
    //不要忘记这里
                                div.appendChild(cover);
    
                            } else {
                                div.appendChild(textLayerDiv);
    //还有这里
                                div.appendChild(cover);
                            }
                            textLayer = this.textLayerFactory.createTextLayerBuilder(textLayerDiv, this.id - 1, this.viewport, this.enhanceTextSelection);
    //这里。。
                            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;
    
    ``

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