PyQt5 signal and slot

PyQt5 的 signal 与 slot 有所改变，例如，先定义一个 ZeroSignal 类：

class ZeroSignal(QObject):
    atzero = pyqtSignal(int)

使用时，一是绑定 slot 如下：

　　　　self.zerosig = ZeroSignal()
       self.zerosig.atzero[int].connect(self.countZero)

然后是找个机会发动之：

def checkZero(self):
        if self.value() == 0:
            self.zerosig.atzero.emit(self.value())

大约如此，完整代码如下：

import os
import sys

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *

class ZeroSignal(QObject):
    atzero = pyqtSignal(int)

class ZeroSpinBox(QSpinBox):
    def __init__(self, parent=None):
        super(ZeroSpinBox, self).__init__(parent)
        self.zeros = 0
        self.valueChanged[int].connect(self.checkZero)
        self.zerosig = ZeroSignal()
        self.zerosig.atzero[int].connect(self.countZero)

    def countZero(self, v):
        if v == 0:
            self.zeros += 1
            print(self.zeros)

    def checkZero(self):
        if self.value() == 0:
            self.zerosig.atzero.emit(self.value())
            



class Form(QDialog):
    def __init__(self, parent=None):
        super(Form, self).__init__(parent)
        
        dial = QDial()
        dial.setNotchesVisible(True)
        spin = ZeroSpinBox()
        layout = QHBoxLayout()
        layout.addWidget(dial)
        layout.addWidget(spin)
        self.setLayout(layout)
        dial.valueChanged.connect(spin.setValue)
        spin.valueChanged.connect(dial.setValue)
        spin.valueChanged.connect(self.emitZero)
        self.setWindowTitle("Sinal and Solt")
        
        self.zerobox = spin 
        self.zerobox.zerosig.atzero[int].connect(self.annouce)

    def emitZero(self, v):
        if v == 0:
            self.zerobox.zerosig.atzero.emit(self.zerobox.zeros)

    def annouce(self, v):
        print("zero count: %d" % v)  # print two times because add ZeroSpinBox emit once

def run():
    app = QApplication(sys.argv)
    form = Form()
    form.show()
    app.exec_()

if __name__ == '__main__':
    run()

关于对话框的代码如下，尤其 NumberLiveDialog 值得推荐：

import sys,math,random,string
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *

class NumberDialog(QDialog):
    def __init__(self, format, parent=None):
        super(NumberDialog, self).__init__(parent)

        thousandsLabel = QLabel("&Thousands separator:")
        self.thousandsEdit = QLineEdit(format["thousandsseparator"])
        thousandsLabel.setBuddy(self.thousandsEdit)
        decimalMarkerLabel = QLabel("Decimal $marker:")
        self.decimalMarkerEdit = QLineEdit(format["decimalmarker"])
        decimalMarkerLabel.setBuddy(self.decimalMarkerEdit)
        decimalPlacesLabel = QLabel("&Decimal places:")
        self.decimalPlacesSpinBox = QSpinBox()
        decimalPlacesLabel.setBuddy(self.decimalPlacesSpinBox)
        self.decimalPlacesSpinBox.setRange(0, 6)
        self.decimalPlacesSpinBox.setValue(format["decimalplaces"])
        self.redNegativesCheckBox = QCheckBox("&Red negative numbers")
        self.redNegativesCheckBox.setChecked(format["rednegatives"])

        buttonBox = QDialogButtonBox(QDialogButtonBox.Ok | QDialogButtonBox.Cancel)
        self.format = format.copy()

        grid = QGridLayout()
        grid.addWidget(thousandsLabel, 0, 0)
        grid.addWidget(self.thousandsEdit, 0, 1)
        grid.addWidget(decimalMarkerLabel, 1, 0)
        grid.addWidget(self.decimalMarkerEdit, 1, 1)
        grid.addWidget(decimalPlacesLabel, 2, 0)
        grid.addWidget(self.decimalPlacesSpinBox, 2, 1)
        grid.addWidget(self.redNegativesCheckBox, 3, 0, 1, 2)
        grid.addWidget(buttonBox, 4, 0, 1, 2)
        self.setLayout(grid)

        buttonBox.accepted.connect(self.accept)
        buttonBox.rejected.connect(self.reject)
        self.setWindowTitle("Number format")

    def accept(self):
        class ThousandsError(Exception): pass 
        class DecimalError(Exception): pass 
        Punctuation = frozenset(" ,;:.")

        thousands = str(self.thousandsEdit.text())
        decimal = str(self.decimalMarkerEdit.text())
        try:
            if len(decimal) == 0:
                raise DecimalError("The decimal marker may not be empty.")
            if len(thousands) > 1:
                raise ThousandsError("The thousands separator may only be empty or one charactor.")
            if len(decimal) > 1:
                raise DecimalError("The decimal marker must be one character.")
            if thousands == decimal:
                raise ThousandsError("The thousands separator and decimal marker must be different.")
            if thousands and thousands not in Punctuation:
                raise ThousandsError("The thousands separator must be in Punctuation.")
            if decimal and decimal not in Punctuation:
                raise DecimalError("The decimal marker must be a punctuation symbol.")
        except ThousandsError as e:
            QMessageBox.warning(self, "Thousands separator error:", str(e))
            self.thousandsEdit.selectAll()
            self.thousandsEdit.setFocus()
            return 
        except DecimalError as e:
            QMessageBox.warning(self, "Decimal marker error:", str(e))
            self.decimalMarkerEdit.selectAll()
            self.decimalMarkerEdit.setFocus()
            return

        self.format["thousandsseparator"] = thousands
        self.format["decimalmarker"] = decimal
        self.format["decimalplaces"] = self.decimalPlacesSpinBox.value()
        self.format["rednegatives"] = self.redNegativesCheckBox.isChecked()

        QDialog.accept(self)

    def numberFormat(self):
        return self.format

class NumberModelessDialog(QDialog):
    changed = pyqtSignal()

    def __init__(self, format, parent=None):
        super(NumberModelessDialog, self).__init__(parent)
        self.setAttribute(Qt.WA_DeleteOnClose)
        punctuationRe = QRegularExpression(r"[ ,;:.]")

        thousandsLabel = QLabel("&Thousands separator:")
        self.thousandsEdit = QLineEdit(format["thousandsseparator"])
        thousandsLabel.setBuddy(self.thousandsEdit)
        self.thousandsEdit.setMaxLength(1)
        self.thousandsEdit.setValidator(QRegularExpressionValidator(punctuationRe, self))

        decimalMarkerLabel = QLabel("Decimal $marker:")
        self.decimalMarkerEdit = QLineEdit(format["decimalmarker"])
        decimalMarkerLabel.setBuddy(self.decimalMarkerEdit)
        self.decimalMarkerEdit.setMaxLength(1)
        self.decimalMarkerEdit.setValidator(QRegularExpressionValidator(punctuationRe, self))

        decimalPlacesLabel = QLabel("&Decimal places:")
        self.decimalPlacesSpinBox = QSpinBox()
        decimalPlacesLabel.setBuddy(self.decimalPlacesSpinBox)
        self.decimalPlacesSpinBox.setRange(0, 6)
        self.decimalPlacesSpinBox.setValue(format["decimalplaces"])
        
        self.redNegativesCheckBox = QCheckBox("&Red negative numbers")
        self.redNegativesCheckBox.setChecked(format["rednegatives"])

        buttonBox = QDialogButtonBox(QDialogButtonBox.Apply | QDialogButtonBox.Close)
        self.format = format

        grid = QGridLayout()
        grid.addWidget(thousandsLabel, 0, 0)
        grid.addWidget(self.thousandsEdit, 0, 1)
        grid.addWidget(decimalMarkerLabel, 1, 0)
        grid.addWidget(self.decimalMarkerEdit, 1, 1)
        grid.addWidget(decimalPlacesLabel, 2, 0)
        grid.addWidget(self.decimalPlacesSpinBox, 2, 1)
        grid.addWidget(self.redNegativesCheckBox, 3, 0, 1, 2)
        grid.addWidget(buttonBox, 4, 0, 1, 2)
        self.setLayout(grid)
        
        buttonBox.button(QDialogButtonBox.Apply).clicked.connect(self.apply)
        buttonBox.rejected.connect(self.reject)
        self.setWindowTitle("Number format")

    def apply(self):
        thousands = str(self.thousandsEdit.text())
        decimal = str(self.decimalMarkerEdit.text())
        if thousands == decimal:
            QMessageBox.warning(self, "Thousands separator error")
            self.thousandsEdit.selectAll()
            self.thousandsEdit.setFocus()
            return 
        if len(decimal) == 0:
            QMessageBox.warning(self, "Decimal marker cannot is empty.")
            self.decimalMarkerEdit.selectAll()
            self.decimalMarkerEdit.setFocus()
            return

        self.format["thousandsseparator"] = thousands
        self.format["decimalmarker"] = decimal
        self.format["decimalplaces"] = self.decimalPlacesSpinBox.value()
        self.format["rednegatives"] = self.redNegativesCheckBox.isChecked()

        self.changed.emit()

class NumberLiveDialog(QDialog):
    changed = pyqtSignal()

    def __init__(self, format, callback, parent=None):
        super(NumberLiveDialog, self).__init__(parent)
        self.format = format
        self.callback = callback
        
        self.setAttribute(Qt.WA_DeleteOnClose)
        punctuationRe = QRegularExpression(r"[ ,;:.]")

        thousandsLabel = QLabel("&Thousands separator:")
        self.thousandsEdit = QLineEdit(format["thousandsseparator"])
        thousandsLabel.setBuddy(self.thousandsEdit)
        self.thousandsEdit.setMaxLength(1)
        self.thousandsEdit.setValidator(QRegularExpressionValidator(punctuationRe, self))

        decimalMarkerLabel = QLabel("Decimal $marker:")
        self.decimalMarkerEdit = QLineEdit(format["decimalmarker"])
        decimalMarkerLabel.setBuddy(self.decimalMarkerEdit)
        self.decimalMarkerEdit.setMaxLength(1)
        self.decimalMarkerEdit.setValidator(QRegularExpressionValidator(punctuationRe, self))

        decimalPlacesLabel = QLabel("&Decimal places:")
        self.decimalPlacesSpinBox = QSpinBox()
        decimalPlacesLabel.setBuddy(self.decimalPlacesSpinBox)
        self.decimalPlacesSpinBox.setRange(0, 6)
        self.decimalPlacesSpinBox.setValue(format["decimalplaces"])
        
        self.redNegativesCheckBox = QCheckBox("&Red negative numbers")
        self.redNegativesCheckBox.setChecked(format["rednegatives"])

        grid = QGridLayout()
        grid.addWidget(thousandsLabel, 0, 0)
        grid.addWidget(self.thousandsEdit, 0, 1)
        grid.addWidget(decimalMarkerLabel, 1, 0)
        grid.addWidget(self.decimalMarkerEdit, 1, 1)
        grid.addWidget(decimalPlacesLabel, 2, 0)
        grid.addWidget(self.decimalPlacesSpinBox, 2, 1)
        grid.addWidget(self.redNegativesCheckBox, 3, 0, 1, 2)
        self.setLayout(grid)
        
        self.thousandsEdit.textEdited.connect(self.checkAndFix)
        self.decimalMarkerEdit.textEdited.connect(self.checkAndFix)
        self.decimalPlacesSpinBox.valueChanged.connect(self.apply)
        self.redNegativesCheckBox.toggled.connect(self.apply)

        self.setWindowTitle("Number format")

    def checkAndFix(self):
        thousands = self.thousandsEdit.text()
        decimal = self.decimalMarkerEdit.text()
        if thousands == decimal:
            self.thousandsEdit.clear()
            self.thousandsEdit.setFocus()
        if len(decimal) == 0:
            self.decimalMarkerEdit.setText(".")
            self.decimalMarkerEdit.selectAll()
            self.decimalMarkerEdit.setFocus()
        self.apply()

    def apply(self):
        thousands = self.thousandsEdit.text()
        decimal = self.decimalMarkerEdit.text()

        self.format["thousandsseparator"] = thousands
        self.format["decimalmarker"] = decimal
        self.format["decimalplaces"] = self.decimalPlacesSpinBox.value()
        self.format["rednegatives"] = self.redNegativesCheckBox.isChecked()

        self.callback()

class Form(QDialog):
    X_MAX = 26
    Y_MAX = 60

    def __init__(self, parent=None):
        super(Form, self).__init__(parent)

        self.numberDlg = None
        self.format = { "thousandsseparator":",", "decimalmarker":".", 
            "decimalplaces":2, "rednegatives": False } 
        self.numbers = {}
        for x in range(self.X_MAX):
            for y in range(self.Y_MAX):
                self.numbers[(x,y)] = 10000 * random.random() - 5000

        self.table = QTableWidget()
        modalButton = QPushButton("Set numbe format...(&Modal)")
        modelessButton = QPushButton("Set number format...(M&odeless)")
        liveButton = QPushButton("Set number format...(&Live)")

        buttonLayout = QHBoxLayout()
        buttonLayout.addStretch()
        buttonLayout.addWidget(modalButton)
        buttonLayout.addWidget(modelessButton)
        buttonLayout.addWidget(liveButton)
        layout = QVBoxLayout()
        layout.addWidget(self.table)
        layout.addLayout(buttonLayout)
        self.setLayout(layout)

        modalButton.clicked.connect(self.setNumberFormatByModal)
        modelessButton.clicked.connect(self.setNumberFormatByModeless)
        liveButton.clicked.connect(self.setNumberFormatByLive)

        self.setWindowTitle("Set Number Format")
        self.refreshTable()

    def refreshTable(self):
        self.table.clear()
        self.table.setRowCount(self.Y_MAX)
        self.table.setColumnCount(self.X_MAX)
        self.table.setHorizontalHeaderLabels(list(string.ascii_uppercase))

        for x in range(self.X_MAX):
            for y in range(self.Y_MAX):
                fraction, whole = math.modf(self.numbers[(x,y)])
                sign = "-" if whole < 0 else ""
                whole = "{0}".format(int(math.floor(abs(whole))))
                digits = []
                for i, digit in enumerate(reversed(whole)):
                    if i and i % 3 == 0:
                        digits.insert(0, self.format["thousandsseparator"])
                    digits.insert(0, digit)
                if self.format["decimalplaces"]:
                    fraction = "{0:.7f}".format(abs(fraction))
                    fraction = self.format["decimalmarker"] + fraction[2:self.format["decimalplaces"]+2]
                else:
                    fraction = ""
                text = "{0}{1}{2}".format(sign, "".join(digits), fraction)
                item = QTableWidgetItem(text)
                item.setTextAlignment(Qt.AlignRight | Qt.AlignVCenter)
                if sign and self.format["rednegatives"]:
                    item.setBackground(Qt.red)
                self.table.setItem(y, x, item)

    def setNumberFormatByModal(self):
        dlg = NumberDialog(self.format, self)
        if dlg.exec_():
            self.format = dlg.numberFormat()
            self.refreshTable()

    def setNumberFormatByModeless(self):
        dlg = NumberModelessDialog(self.format, self)
        dlg.show()
        dlg.changed.connect(self.refreshTable)

    def setNumberFormatByLive(self):
        if self.numberDlg is None:
            self.numberDlg = NumberLiveDialog(self.format, self.refreshTable, self)
        self.numberDlg.show()
        self.numberDlg.raise_()
        self.numberDlg.activateWindow()

if __name__ == "__main__":
    app = QApplication(sys.argv)
    form = Form()
    form.show()
    app.exec_()

 关于主窗口 (fileload function need add a bool parameter for recentfiles) 的代码：imagechanger

 运行效果图如下：

        

 《Python GUI Qt 快速开放指南》部分例子： PyQt5-Code