使用按钮的 PyQt5 Qlabel QPixmap 旋转

Question

所以我试图用按钮旋转 QLabel，但我收到错误并且不确定发生了什么：

Process finished with exit code -1073740791 (0xC0000409)

我使用这个 post 作为参考 Rotating a pixmap in pyqt4 gives undesired translation 但是因为这是针对 PyQt4 我需要做一些改变。

谁能解释一下我做错了什么？

from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(355, 153)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(20, 20, 75, 23))
        self.pushButton.setObjectName("pushButton")
        pixmap = self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(120, 20, 81, 81))
        self.label.setText("")
        self.label.setPixmap(QtGui.QPixmap("../QComboBox/img/Arrows Green.png"))
        self.label.setScaledContents(True)
        self.label.setObjectName("label")
        self.label.setAlignment(QtCore.Qt.AlignCenter)
        self.comboBox = QtWidgets.QComboBox(self.centralwidget)
        self.comboBox.setGeometry(QtCore.QRect(240, 50, 69, 22))
        self.comboBox.setObjectName("comboBox")
        self.comboBox.addItem("")
        self.comboBox.addItem("")
        self.comboBox.addItem("")
        self.comboBox.addItem("")
        self.lineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit.setGeometry(QtCore.QRect(240, 80, 81, 20))
        self.lineEdit.setObjectName("lineEdit")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 355, 21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Rotate 5deg"))
        self.comboBox.setItemText(0, _translate("MainWindow", "Rotate 5deg"))
        self.comboBox.setItemText(1, _translate("MainWindow", "Rotate 10deg"))
        self.comboBox.setItemText(2, _translate("MainWindow", "Rotate 15deg"))
        self.comboBox.setItemText(3, _translate("MainWindow", "Rotate 20deg"))

        self.pushButton.clicked.connect(self.rotate_pixmap)

    def rotate_pixmap(self):
        pixmap = self.label.setPixmap(QtGui.QPixmap("../QComboBox/img/Arrows Green.png"))
        rotation += 5
        transform = QtGui.QTransform().rotate(rotation)
        pixmap = pixmap.transformed(transform, QtCore.Qt.SmoothTransformation)
        self.label.setPixmap(pixmap)


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

示例视图

我的下一步是根据 QCombobox 和用户输入实现旋转，但那是以后的事。

Answer 1

建议您从控制台运行您的代码以获得更具描述性的错误消息，如果您这样做，您将得到：

Traceback (most recent call last):
  File "main.py", line 55, in rotate_pixmap
    rotation += 5
UnboundLocalError: local variable 'rotation' referenced before assignment
Aborted (core dumped)

原因很明显，您正在累积一个以前从未分配过的变量，这种情况下的解决方案是创建一个只初始化一次的属性。

即使更正该错误，也会出现另一个错误：

Traceback (most recent call last):
  File "main.py", line 59, in rotate_pixmap
    pixmap = pixmap.transformed(transform, QtCore.Qt.SmoothTransformation)
AttributeError: 'NoneType' object has no attribute 'transformed'
Aborted (core dumped)

而且你也可以知道错误的原因，setPixmap方法并没有return任何东西。解决办法就是不用setPixmap，复制QPixmap。

最后，建议不要修改Qt Designer生成的代码，必须通过执行pyuic5 your_file.ui -o gui.py -x

恢复.py

然后使用下面的.py:

main.py

from PyQt5 import QtCore, QtGui, QtWidgets


from gui import Ui_MainWindow


class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setupUi(self)
        self.rotation = 0
        self.pushButton.clicked.connect(self.rotate_pixmap)

    def rotate_pixmap(self):
        pixmap = QtGui.QPixmap("../QComboBox/img/Arrows Green.png")
        self.rotation += 5
        transform = QtGui.QTransform().rotate(self.rotation)
        pixmap = pixmap.transformed(transform, QtCore.Qt.SmoothTransformation)
        self.label.setPixmap(pixmap)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())

使用按钮的 PyQt5 Qlabel QPixmap 旋转

PyQt5 Qlabel QPixmap Rotation using pushButton

python

qlabel

pyqt5