window.print铺满纸张打印

问题

打印A和B两个区域, 高度大于一张A4纸高度, 如何保证两个区域分别铺满在A4纸上
A4纸宽度: 210mm; 高度:297mm;

普通打印:

思路:

打印内容超出一张纸高度时,根据纸张大小,设置打印区域的zoom,按比例缩小打印

依赖函数

Print.js,采用iframe绘制并打印 (复制调用即可)

/***** iframe打印
 * @param dom            打印区域的class, id
 * @param options.margin  控制页眉页脚, 默认 4mm
 * @param options.padding 打印边距, 默认 '0 0'
 * @method options.afterprint 打印结束后回调
 * @method options.cancel 取消打印后回调
 * 
 * **/


const Print = function(dom, options) {
  if (!(this instanceof Print)) return new Print(dom, options);

  this.options = this.extend(
    {
      noPrint: ".no-print",
    },
    options
  );

  if (typeof dom === "string") {
    this.dom = document.querySelector(dom);
  } else {
    this.isDOM(dom);
    this.dom = this.isDOM(dom) ? dom : dom.$el;
  }

  this.init();
};
Print.prototype = {
  init: function() {
    var content = this.getStyle() + this.getHtml();
    this.writeIframe(content);
  },
  extend: function(obj, obj2) {
    for (var k in obj2) {
      obj[k] = obj2[k];
    }
    return obj;
  },

  getStyle: function() {
    var str = "",
      styles = document.querySelectorAll("style,link");
    for (var i = 0; i < styles.length; i++) {
      str += styles[i].outerHTML;
    }
 


    str +=
    "<style>" +
    (this.options.noPrint ? this.options.noPrint : ".no-print") +
    "{display:none;}</style>";
    
    str += `<style>
    @media print { 
      @page { margin: ${this.options.margin || '4mm'}; padding: ${this.options.padding || '0 0'}; width:210mm;height:290mm} 
      body {  
        -webkit-print-color-adjust:exact;-moz-print-color-adjust:exact;-ms-print-color-adjust:exact;print-color-adjust:exact; 
      } 
    }
    </style>`;


    return str;
  },

  getHtml: function() {
    var inputs = document.querySelectorAll("input");
    var textareas = document.querySelectorAll("textarea");
    var selects = document.querySelectorAll("select");

    for (var k = 0; k < inputs.length; k++) {
      if (inputs[k].type == "checkbox" || inputs[k].type == "radio") {
        if (inputs[k].checked == true) {
          inputs[k].setAttribute("checked", "checked");
        } else {
          inputs[k].removeAttribute("checked");
        }
      } else if (inputs[k].type == "text") {
        inputs[k].setAttribute("value", inputs[k].value);
      } else {
        inputs[k].setAttribute("value", inputs[k].value);
      }
    }

    for (var k2 = 0; k2 < textareas.length; k2++) {
      if (textareas[k2].type == "textarea") {
        textareas[k2].innerHTML = textareas[k2].value;
      }
    }

    for (var k3 = 0; k3 < selects.length; k3++) {
      if (selects[k3].type == "select-one") {
        var child = selects[k3].children;
        for (var i in child) {
          if (child[i].tagName == "OPTION") {
            if (child[i].selected == true) {
              child[i].setAttribute("selected", "selected");
            } else {
              child[i].removeAttribute("selected");
            }
          }
        }
      }
    }

    return this.dom.outerHTML;
  },

  writeIframe: function(content) {
    var w,
      doc,
      iframe = document.createElement("iframe"),
      f = document.body.appendChild(iframe);
    iframe.id = "myIframe";
    iframe.setAttribute(
      "style",
      "position:absolute;width:0;height:0;top:-10px;left:-10px;"
    );
   
    w = f.contentWindow || f.contentDocument;
    doc = f.contentDocument || f.contentWindow.document;
    doc.open();
    doc.write(content);
    doc.close();
    var _this = this;
    
    iframe.onload = function() {
      w.onbeforeprint = _this.options.beforeprint;
      w.onafterprint = _this.options.afterprint;
      // iframe.contentWindow.print();
      _this.toPrint(w);
      setTimeout(function() {
        document.body.removeChild(iframe);
      }, 100);
    };
  },

  toPrint: function(frameWindow) {
    var _t = this;
    try {
      setTimeout(function() {
        frameWindow.focus();
        try {
          if (!frameWindow.document.execCommand("print", false, null)) {
            
            frameWindow.print();
          }
        } catch (e) {
          
          frameWindow.print();
        }
        frameWindow.close();
        typeof _t.options.cancel === "function" && _t.options.cancel();
        frameWindow.onbeforeprint = null;
        frameWindow.onafterprint = null;
      }, 10);
    } catch (err) {
      console.log("err", err);
    }
  },

  isDOM:
    typeof HTMLElement === "object"
      ? function(obj) {
          return obj instanceof HTMLElement;
        }
      : function(obj) {
          return (
            obj &&
            typeof obj === "object" &&
            obj.nodeType === 1 &&
            typeof obj.nodeName === "string"
          );
        },
};
export default Print 

unitChange.js, px - mm 单位互相转换函数 (复制调用即可)

//  px <-> mm  单位互相转换

/**
 * 获取DPI 每英寸像素点
 * @returns {Array}
 */
let conversion_getDPI = function() {
  var DPI = 0;
  if (window.screen.deviceXDPI) {
    DPI = window.screen.deviceXDPI;
  } else {
    var tmpNode = document.createElement("DIV");
    tmpNode.style.cssText =
      "width:1in;height:1in;position:absolute;left:0px;top:0px;z-index:99;visibility:hidden";
    document.body.appendChild(tmpNode);
    DPI = parseInt(tmpNode.offsetWidth); 
    tmpNode.parentNode.removeChild(tmpNode);
  } 
  return DPI;
};

// 1 英寸=25.4 毫米

/**
 * px转换为mm
 * @param value
 * @returns {number}
 */
let px2mm = function(value) {
  var inch = value / conversion_getDPI();
  var c_value = inch * 25.4;
  //      console.log(c_value);
  return c_value;
};

/**
 * mm转换为px
 * @param value
 * @returns {number}
 */
let mm2px = function(value) {
  var inch = value / 25.4;
  var c_value = inch * conversion_getDPI();
  //      console.log(c_value);
  return c_value;
};
export default {
    mm2px,
    px2mm
};

解决问题

两个区域分别铺满纸张打印:

<template>
  <div
    style="
      height: 100%;
      display: flex;
      flex-direction: column;
      width: 210mm;
      align-items: flex-end;
    "
  >
    <button style="padding: 0 10px" @click="doprint">分页铺满纸打印</button>
    <div id="printContent">
      <div class="ctx" style="height: 320mm; background: pink">
        我是打印的内容A
      </div>
      <div class="ctx" style="height: 320mm; background: #6dcc16">
        我是打印的内容B
      </div>
    </div>
  </div>
</template>
<style lang="scss" scoped>
#printContent {
  flex: 1;

  width: 210mm;
  overflow: auto;
  .ctx {
    color: #000;
    width: 100%;
    writing-mode: vertical-lr;
    text-align: center;
    display: flex;
    align-items: center;
    font-size: 60px;
    justify-content: center;
    border: 5px solid blue;
  }
}
</style>

<script>
import unitChange from "@/utils/unitChange.js";
import Print from "@/utils/Print.js";

export default {
  data() {
    return {
      zoomStatus: false,
    };
  },
  methods: {
    doprint() {
      this.setPrintStyle();
      Print("#printContent", {
        afterprint: () => {},
        cancel: () => {},
      });
    },
    //打印区域分页并铺满A4纸打印
    setPrintStyle() {
      if (this.zoomStatus) return;
      this.zoomStatus = true;
      // 保证打印正好铺满A4高度
      let A4height = 297; // A4高度297mm
      let ctxpage = document.querySelectorAll(".ctx");
      ctxpage.forEach((i, k) => {
        let eachpage_mm = unitChange.px2mm(i.clientHeight); // 单位px转mm
        console.log(k + "页高度px:", i.clientHeight, "高度mm:", eachpage_mm);

        //高度大于A4,则按比例缩小打印区域
        if (eachpage_mm > A4height) {
          let zoom = A4height / eachpage_mm;
          console.log(k + "页zoom:", zoom);
          i.style.zoom = zoom;
        }
      });
    },
  },
};


</script>