PyQt5 StringSpinBox – 循环字符串

在这篇文章中，我们将看到如何使字符串的值重复，当最后一个值达到时，它应该回到第一个值，同样，当第一个值之后的值被递减时，它应该回到最后一个值。为了做到这一点，我们必须改变StringSpinBox的自定义类代码。

下面是自定义StringSpinBox类的代码

# custom class for String Spin Box
class StringBox(QSpinBox):

    # constructor
    def __init__(self, parent=None):
        super(StringBox, self).__init__(parent)

        # list of strings
        strings = ["a", "b", "c", "d", "e", "f", "g"]


        # calling set Strings method with
        # adding blank value in front and in end
        self.setStrings(["BLANK"] + strings + ["BLANK"])

        # show first value from index 1
        self.setValue(1)

    def reset_spin(self):
        if self.value() == len(self.strings()) - 1:
            self.setValue(0)

    # method setString
    # similar to set value method
    def setStrings(self, strings):

        # making strings list
        strings = list(strings)

        # making tuple from the string list
        self._strings = tuple(strings)

        # creating a dictionary
        self._values = dict(zip(strings, range(len(strings))))

        # setting range to it the spin box
        self.setRange(0, len(strings)-1)

    # overwriting the textFromValue method
    def textFromValue(self, value):

        # returning string from index
        # _string = tuple
        return self._strings[value]

    # overwriting the stepBy method
    # method that get called when values get incremented or decremented
    def stepBy(self, step):

        # checking if current value is 1 and step is -1
        # step = -1 means decrement
        if self.value() == 1 and step == -1:

            # set current value to maximum
            self.setValue(self.maximum())

        # checking if current value is maximum -1 and step is 1
        # step = 1 means Increment
        elif self.value() == self.maximum() - 1 and step == 1:

            # setting current value to 0
            self.setValue(0)

        # calling stepBy method of QSpinBox
        QSpinBox.stepBy(self, step)

解释： 在String spin box自定义类中覆盖了stepBy方法，该方法在增量或减量发生时被调用，检查是否有减量且当前值为最小值，然后将其值改为最大值，同样，如果有增量且当前值为最大值，则将其值改为最小-1值。

以下是实现方法

# importing libraries
from PyQt5.QtWidgets import * 
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import * 
from PyQt5.QtCore import * 
import sys
  
# custom class for String Spin Box
class StringBox(QSpinBox):
  
    # constructor
    def __init__(self, parent = None):
        super(StringBox, self).__init__(parent)
  
        # list of strings
        strings = ["a", "b", "c", "d", "e", "f", "g"]
  
  
        # calling set Strings method with
        # adding blank value in front and in end
        self.setStrings(["BLANK"] + strings + ["BLANK"])
  
        # show first value from index 1
        self.setValue(1)
  
    def reset_spin(self):
        if self.value() == len(self.strings()) - 1:
            self.setValue(0)
  
    # method setString
    # similar to set value method
    def setStrings(self, strings):
  
        # making strings list
        strings = list(strings)
  
        # making tuple from the string list
        self._strings = tuple(strings)
  
        # creating a dictionary
        self._values = dict(zip(strings, range(len(strings))))
  
        # setting range to it the spin box
        self.setRange(0, len(strings)-1)
  
    # overwriting the textFromValue method
    def textFromValue(self, value):
  
        # returning string from index
        # _string = tuple
        return self._strings[value]
  
    # overwriting the stepBy method
    # method that get called when values incremented
    def stepBy(self, step):
  
        # checking if current value is 1 and step is -1
        # step = -1 means decrement
        if self.value() == 1 and step == -1:
  
            # set current value to maximum
            self.setValue(self.maximum())
  
        # checking if current value is maximum -1 and step is 1
        # step = 1 means Increment
        elif self.value() == self.maximum() - 1 and step == 1:
  
            # setting current value to 0
            self.setValue(0)
  
        # calling stepBy method by QSpinBox
        QSpinBox.stepBy(self, step)
  
class Window(QMainWindow):
  
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("Python ")
  
        # setting geometry
        self.setGeometry(100, 100, 600, 400)
  
        # calling method
        self.UiComponents()
  
        # showing all the widgets
        self.show()
  
        # method for widgets
    def UiComponents(self):
  
        # creating a string spin box
        string_spin_box = StringBox(self)
  
        # setting geometry to the spin box
        string_spin_box.setGeometry(100, 100, 200, 40)
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())