Python PyQt5的基本知识_python pyqt5 class __init__

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Python PyQt5的基本知识+应用+案例

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Python PyQt5的基本应用

Demo1 加载图片、文件

 def initUI(self):
        layout = QVBoxLayout()
        self.button1 = QPushButton("加载图片")
        self.button1.clicked.connect(self.loadImage)
        layout.addWidget(self.button1)

        self.imageLabel = QLabel()
        layout.addWidget(self.imageLabel)

        self.button2 = QPushButton("加载文本文件")
        self. button2.clicked.connect(self.loadText)
        layout.addWidget(self.button2)

        self.contents = QTextEdit()
        layout.addWidget(self.contents)

        self.setLayout(layout)
        self.setWindowTitle("文件对话框")

    def loadImage(self):
        fname,_ = QFileDialog.getOpenFileName(self,"打开文件","."," 图像文件(*.jpg *.png)")
        self.imageLabel.setPixmap((QPixmap(fname)))

    def loadText(self):
        dialog = QFileDialog()
        dialog.setFileMode(QFileDialog.AnyFile)
        dialog.setFilter(QDir.Files)
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Demo1 运行的效果：

Demo2 拖拽文字，并添加到comboBox

class MyComboBox(QComboBox):    #继承别人的控件
    def __init__(self):
        super(MyComboBox,self).__init__()
        self.setAcceptDrops(True)

    def dragEnterEvent(self, e):
        print(e)
        if e.mimeData().hasText():
            e.accept()
        else:
            e.ignore()

    def dropEvent(self, e):
        self.addItem(e.mimeData().text())


class DrapDropDemo(QWidget):
    def __init__(self):
        super(DrapDropDemo,self).__init__()
        formLayout = QFormLayout()
        formLayout.addRow(QLabel("请将文本拖动到下拉列表中"))
        lineEdit = QLineEdit()
        lineEdit.setDragEnabled(True)   #QlineEdit是可拖动的

        combo = MyComboBox()
        formLayout.addRow(lineEdit,combo)
        self.setLayout(formLayout)
        self.setWindowTitle("拖拽")


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Demo2运行效果

Demo3 绘制各种图形

    def paintEvent(self, event):
        qp = QPainter()
        qp.begin(self)

        qp.setPen(Qt.blue)

        #绘制弧
        rect = QRect(0,10,100,100)
        #alen:1个alen等于1/16度  45*16（表示45度的弧）
        qp.drawArc(rect,0,90*16)
        #通过弧绘制圆
        qp.setPen(Qt.red)
        qp.drawArc(120,10,100,100,0,360*16)
        #带弦的弧
        qp.setPen(Qt.green)
        qp.drawChord(0,120,100,100,12,130*16 )
        #绘制扇形
        qp.setPen(Qt.darkGray)
        qp.drawPie(10,240,100,100,12,130*16)

        #绘制椭圆
        qp.setPen(Qt.gray)
        qp.drawEllipse(120,120,150,100)


        #绘制5边形
        point1 = QPoint(250,300)
        point2 = QPoint(320,350)
        point3 = QPoint(430,380)
        point4 = QPoint(400,500)
        point5 = QPoint(100,533)

        polygon = QPolygon([point1,point2,point3,point4,point5])
        qp.drawPolygon(polygon)
        
        qp.end()
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Demo3 的运行效果

Demo4 绘制正弦波形（两个周期）

class DrawPoints(QWidget):
    def __init__(self):
        super(DrawPoints,self).__init__()
        self.resize(300,300)
        self.setWindowTitle("绘制两个周期的正弦波")

    def paintEvent(self,event):
        painter = QPainter()
        painter.begin(self)
        painter.setPen(Qt.blue)
        size = self.size()

        for i in range(1000):
            x = 100 * (-1+2.0*i/1000 )+size.width()/2.0
            y = -50* math.sin((x-size.width()/2.0)* math.pi/50) +size.height()/2.0
            painter.drawPoint(x,y)

        painter.end()
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Demo4 运行结果