利用Websocket实现网页调用打印功能

最新推荐文章于 2023-12-22 16:10:29 发布

原创最新推荐文章于 2023-12-22 16:10:29 发布 · 1.2w 阅读

CC 4.0 BY-SA版权

本文介绍了如何解决项目中遇到的打印问题，通过创建自定义的打印控件，利用Websocket和PyQT的QPrinter库，实现了根据用户需求选择不同打印机进行打印的功能，避免了频繁设置打印机的困扰。

最近项目遇到打印问题，情景是一台机子连着多个打印机，需要打印小样、条码、A4等等，原本以为调用window.print直接了事。可是客户不买帐啊，每次打印不同的文件都要设置不同的打印机，客户直接不干了，没办法，只好给他整。网上搜了好几个打印控件，感觉都不顺心，于是干脆就自己写一个，便想用websocket+pyqt做个打印控件。

直接撸代码吧，python丰富的库直接省了很多事情，使用tornado的websocket+pyqt的QPrinter,几行代码就搞定了

#-*- coding:utf8 -*-
import tornado.web
import tornado.ioloop
import tornado.httpserver
import tornado.options
import sys

from tornado.options import define,options
from tornado.websocket import WebSocketHandler

import json

from PyQt5.QtWidgets import QApplication
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtPrintSupport import QPrinterInfo,QPrinter


define("port",default=8889,type=int)
def printList():
    printerInfo = QPrinterInfo()
    return printerInfo.availablePrinterNames()

def printContent(printer,context,params):
    printerInfo = QPrinterInfo()
    p = QPrinter()
    for item in printerInfo.availablePrinters():
        if printer == item.printerName():
            print(printer)
            p = QPrinter(item,QPrinter.PrinterResolution)
            break
    p.setPageMargins(0, 0, 0, 0, QPrinter.Pica)

    p.setFullPage(True)
    docWidth = params['width'];
    docHeight = params['height'];
    orit = params['orientation']
    # if orit == "landscape":
    #     p.setOrientation(QPrinter.Landscape)
    # else:
    #     p.setOrientation(QPrinter.Portrait)
    print(docWidth * 35)
    docSize = QSizeF(docWidth * 35,docHeight*35)
    doc = QTextDocument()
    doc.setDocumentMargin(5)
    doc.setPageSize(docSize)
    #doc.setDefaultFont(QFont("Microsoft YaHei", 4, QFont.Normal))
    #doc.setIndentWidth(80)

    doc.setHtml(u'%s' % context)
    doc.print(p)

def printed(state):
    print(state)

class PrinterHandler(WebSocketHandler):
    def open(self):
        pass

    def on_message(self, message):
        command = json.loads(message)
        printype = command['type']
        if printype == "print":
            printer = command['printer']
            content = command['content']
            params = command['params']
            print(printer)
            try:
                printContent(printer, content,params)
                ret = {"code": 200, "msg": "打印成功"}
                self.write_message(json.dumps(ret))
            except Exception as e:
                ret = {"code":500,"msg":"打印失败，错误信息：" + e}
                self.write_message(json.dumps(ret))
        elif printype == "list":
            ## TODO：获取打印机列表
            ls = printList()
            ret = {"code":204,"msg":"获取打印机列表成功","data":ls}
            self.write_message(json.dumps(ret))

    def on_close(self):
        pass

    def check_origin(self, origin):
        return True  # 允许WebSocket的跨域请求

if __name__ == "__main__":
    tornado.options.parse_command_line()
    app = QApplication(sys.argv)
    wapp = tornado.web.Application([(r"/printer",PrinterHandler)])
    http_server = tornado.httpserver.HTTPServer(wapp)
    http_server.listen(options.port)
    tornado.ioloop.IOLoop.current().start()
    app.exec_()

前端也可以封装一成了Printer类就可以了

贴个git地址^-^