在 Tkinter 中打开打印机选择 window

Question

我遇到问题可能是因为我缺乏知识。我想打开 windows 对话框来选择打印机并使用 Tkinter 发送打印（到打印机）。

目前，我使用代码将 Tkinter 与 Wxpython 相关联，并使其异步创建一个单独的进程。

这是上面提到的代码：

from tkinter import *
from threading import Thread
import wx

def f_imprimir(ventana, entry):
    class TextDocPrintout(wx.Printout):
        def __init__(self):
            wx.Printout.__init__(self)

        def OnPrintPage(self, page):
            dc = self.GetDC()

            ppiPrinterX, ppiPrinterY = self.GetPPIPrinter()     
            ppiScreenX, ppiScreenY = self.GetPPIScreen()     
            logScale = float(ppiPrinterX)/float(ppiScreenX)

            pw, ph = self.GetPageSizePixels()
            dw, dh = dc.GetSize()     
            scale = logScale * float(dw)/float(pw)
            dc.SetUserScale(scale, scale)

            logUnitsMM = float(ppiPrinterX)/(logScale*25.4)

            ### Print code ###

            return True

    class PrintFrameworkSample(wx.Frame):        
        def OnPrint(self):
            pdata = wx.PrintData()
            pdata.SetPaperId(wx.PAPER_A4)
            pdata.SetOrientation(wx.LANDSCAPE)

            data = wx.PrintDialogData(pdata)
            printer = wx.Printer(data)

            printout = TextDocPrintout()

            useSetupDialog = True

            if not printer.Print(self, printout, useSetupDialog) and printer.GetLastError() == 
wx.PRINTER_ERROR:

                wx.MessageBox(

                    "There was a problem printing.\n"

                    "Perhaps your current printer is not set correctly?",

                    "Printing Error", wx.OK)

            else:
                data = printer.GetPrintDialogData() 
                pdata = wx.PrintData(data.GetPrintData()) # force a copy

            printout.Destroy()
            self.Destroy()

    app=wx.App(False)
    PrintFrameworkSample().OnPrint()
    entry.config(state="normal")


def process(ventana, entry):
    entry.config(state="disable")
    t = Thread(target=f_imprimir, args=(ventana,entry))
    t.start()

v = Tk()
entry = Entry(v)
entry.pack()
v.bind("a", lambda a:process(v,entry))

当 wx.app 完成时，打印机选择器关闭时可能会发生这种情况，我打算将条目的状态更改为 "normal"。但是当将条目的状态更改为 "normal" 时它会抛出错误，我想这是因为 window 和我发送的订单在不同的进程中。错误将是：

Exception in thread Thread-1:
Traceback (most recent call last):
  File "C:\Python38-32\lib\threading.py", line 932, in _bootstrap_inner
    self.run()
  File "C:\Python38-32\lib\threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\DANTE\Google Drive\JNAAB\DESARROLLO\pruebas\pedasito.py", line 65, in f_imprimir
    entry.config(state="normal")
  File "C:\Python38-32\lib\tkinter\__init__.py", line 1637, in configure
    return self._configure('configure', cnf, kw)
  File "C:\Python38-32\lib\tkinter\__init__.py", line 1627, in _configure
    self.tk.call(_flatten((self._w, cmd)) + self._options(cnf))
RuntimeError: main thread is not in main loop

有没有人有这个问题的解决方案或创建打印 window 而不阻止 TCL window 并且能够阻止条目的替代方法？如果有办法做到这一点或使用 Tkinter 发送打印并避免这种混乱，那就更好了。谢谢。

Answer 1

我不使用 wxPython 但是你的错误是由于与 tkinter 相关的线程问题。 Tkinter 喜欢在主线程中，尝试将小部件传递到单独的线程可能会导致问题。但是，您的输入字段已经在全局命名空间中，因此您无需传递它。

只需在需要时从您的线程更新即可。

我会在你的 if/else 条件下这样做，所以它只会在正确的时间发生。

像这样的东西会起作用：请注意，您实际上需要对传递的值执行某些操作。现在 none 您的代码实际上会打印空白页以外的任何内容。

import tkinter as tk
from threading import Thread
import wx


def f_imprimir(value):
    # here you can see the value of entry was passed as a string so we can avoid any issues with the widget
    print(value)
    class TextDocPrintout(wx.Printout):
        def __init__(self):
            wx.Printout.__init__(self)

        def OnPrintPage(self, page):
            dc = self.GetDC()
            ppiPrinterX, ppiPrinterY = self.GetPPIPrinter()     
            ppiScreenX, ppiScreenY = self.GetPPIScreen()     
            logScale = float(ppiPrinterX)/float(ppiScreenX)

            pw, ph = self.GetPageSizePixels()
            dw, dh = dc.GetSize()     
            scale = logScale * float(dw)/float(pw)
            dc.SetUserScale(scale, scale)
            logUnitsMM = float(ppiPrinterX)/(logScale*25.4)
            return True

    class PrintFrameworkSample(wx.Frame):        
        def OnPrint(self):
            pdata = wx.PrintData()
            pdata.SetPaperId(wx.PAPER_A4)
            pdata.SetOrientation(wx.LANDSCAPE)
            data = wx.PrintDialogData(pdata)
            printer = wx.Printer(data)
            printout = TextDocPrintout()
            useSetupDialog = True

            if not printer.Print(self, printout, useSetupDialog) and printer.GetLastError() == wx.PRINTER_ERROR:

                wx.MessageBox("There was a problem printing.\n\n"
                              "Perhaps your current printer is not set correctly?\n\n"
                              "Printing Error", wx.OK)
                entry.config(state="normal")
            else:
                data = printer.GetPrintDialogData() 
                pdata = wx.PrintData(data.GetPrintData())  # force a copy
                entry.config(state="normal")

            printout.Destroy()
            self.Destroy()

    app = wx.App(False)
    PrintFrameworkSample().OnPrint()



def process(_=None):
    entry.config(state="disable")
    t = Thread(target=f_imprimir, args=(entry.get(),))
    t.start()


v = tk.Tk()
entry = tk.Entry(v)
entry.pack()
v.bind("<Return>", process)
v.mainloop()

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