《PyQt5 快速编程》例子注释

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Fraction Slider.py的qt4代码修改后的qt5版本

import platformimport PyQt5from PyQt5.QtCore import QPointF,QRectF,QSize,Qt,QObject,pyqtSignalfrom PyQt5.QtGui import QColor,QFont,QFontMetricsF,QPainter,QPalette,QPolygonF,QKeyEventfrom PyQt5.QtWidgets import (QApplication,QDialog,QGridLayout,QLCDNumber,                                QLabel,QSizePolicy,QSpinBox,QWidget)# 这段代码貌似与界面x11有关 暂时看不明白要干嘛X11=hasattr(PyQt5.QtGui,"qt_x11_wait_for_window_manager")X11 = Truetry:    from PyQt5.QtGui import qt_x11_wait_for_window_managerexcept ImportError:    X11 = Falseclass FractionSlider(QWidget):    #定义边距    XMARGIN=12    YMARGIN=9    WSTRING='999'    #定义一个valueChanged的信号    # valueChanged=signal().valueChanged    valueChanged=pyqtSignal(int)    #定义初始化函数    def __init__(self,numerator=0,denominator=10,parent=None):        super(FractionSlider,self).__init__(parent)        self.__numerator=numerator        self.__denominator=denominator        #可以通过滚轮接受焦点        self.setFocusPolicy(Qt.WheelFocus)        #可以伸展和收缩，不过sizeHint() 的返回值规定了        # widget 能缩小到的最小尺寸,同时它比 Preferred 更具优势去获取额外空间        self.setSizePolicy(QSizePolicy(QSizePolicy.MinimumExpanding,QSizePolicy.Fixed))    def decimal(self):        return self.__numerator/float(self.__denominator)    def fraction(self):        return self.__numerator,self.__denominator    def sizeHint(self):        return self.minimumSizeHint()    #计算整个界面完全显示的最小的大小    def minimumSizeHint(self):        font=QFont(self.font())        font.setPointSize(font.pointSize()-1)        #计算对应该字体的字符的大小        fm=QFontMetricsF(font)        #返回大小存疑        return QSize(fm.width(FractionSlider.WSTRING)*self.__denominator,                      fm.height()*4+FractionSlider.YMARGIN)    def setFraction(self,numerator,denominator=None):        if denominator is not None:            if 3<=denominator<=60:                self.__denominator=denominator            else:                raise ValueError('denominator out of range')        if 0<=numerator<=self.__denominator:            self.__numerator=numerator        else:            raise ValueError('numerator out of range')        #更新widget绘制        self.update()        self.updateGeometry()    #鼠标按下的事件    def mousePressEvent(self, event):        if event.button()==Qt.LeftButton:            self.moveSlider(event.x())            event.accept()        else:            #不是左键的话就执行默认的事件 其实这段代码可以不写就是将型信号传递给上级            QWidget.mousePressEvent(self,event)    def mouseMoveEvent(self,event):        #event.x() 是不是指的是widget内部的坐标        self.moveSlider(event.x())    def moveSlider(self,x):        span=self.width()-2*FractionSlider.XMARGIN        offset=span-x+FractionSlider.XMARGIN        #根据鼠标的位置来确定分子的大小        numerator=int(round(self.__denominator*(1-offset/span)))        numerator=max(0,min(numerator,self.__denominator))        if numerator!=self.__numerator:            self.__numerator=numerator            #发射值改变的信号             #emit参数可以附带参数信息            self.valueChanged.emit(self.__numerator)            #重新绘制图形             self.update()    #根据按下的按键的不同确定change的变化程度    def KeyPressEvent(self, event: QKeyEvent):        change=0        key=None        if key==Qt.Key_Home:            change=-self.__denominator        elif key in (Qt.Key_Up,Qt.Key_Right):            change=1        elif key in (Qt.Key_Down,Qt.Key_Right):            change=-1        elif key==Qt.Key_PageDown:            change=-(self.__denominator//10+1)        elif key==Qt.Key_PageUp:            change=self.__denominator//10+1        elif key==Qt.Key_End:            change=self.__denominator        if change:            numerator=self.__numerator+change            numerator=max(0,min(numerator,self.__denominator))            if numerator!=self.__numerator:                self.__numerator=numerator                self.valueChanged.emit(self.__numerator)                self.update()            event.accept()        else:            QWidget.keyPressEvent(self,event)    def paintEvent(self, event=None):        font=QFont(self.font())        #设定挂件的字体比正常的字体小一号        font.setPointSize(font.pointSize()-1)        fm=QFontMetricsF(font)        fracWidth=fm.width(FractionSlider.WSTRING)        indent=fm.boundingRect('9').width()/2.0        if not X11:            fracWidth*=1.5        span=self.width()-self.XMARGIN*2        value=self.decimal()        painter=QPainter(self)        #设置反锯齿         painter.setRenderHint(QPainter.Antialiasing)        painter.setRenderHint(QPainter.TextAntialiasing)        #QPalette参见page337        #pen用于绘制文字和轮廓 调色板设定颜色        painter.setPen(self.palette().color(QPalette.Mid))        #brush负责填充背景        painter.setBrush(self.palette().brush(QPalette.AlternateBase))        painter.drawRect(self.rect())        #绘制了一个进度条区域方便指针在上面滑动        segColor=QColor(Qt.green).darker(120)        #darker函数默认参数是200        segLineColor=segColor.darker()        painter.setPen(segLineColor)        painter.setBrush(segColor)        #设定边界以及绘图区域        painter.drawRect(FractionSlider.XMARGIN,FractionSlider.YMARGIN,                          span,fm.height())        textColor=self.palette().color(QPalette.Text)        segWidth=span/self.__denominator        segHeight=fm.height()*2        nRect=fm.boundingRect(FractionSlider.WSTRING)        x=FractionSlider.XMARGIN        ymargin=FractionSlider.YMARGIN        yOffeset=segHeight+fm.height()        for i in range(self.__denominator+1):            painter.setPen(segLineColor)            #draw from pos1 to pos2            painter.drawLine(x,ymargin,x,segHeight)            painter.setPen(textColor)            y=segHeight            #绘制分子            rect=QRectF(nRect)            #确定矩形区域的中心进行分子的绘制            rect.moveCenter(QPointF(x,y+fm.height()/2.0))            painter.drawText(rect,Qt.AlignCenter,str(i))            #绘制分母            y=yOffeset            rect.moveCenter(QPointF(x,y+fm.height()/2.0))            painter.drawText(rect,Qt.AlignCenter,str(self.__denominator))              #绘制分割线 indent是半个字宽            painter.drawLine(QPointF(rect.left()+indent,y),QPointF(rect.right()-indent,y))            x+=segWidth        #绘制三角形刻度标记图标        #其实这段代码写的是有问题的 只有 XMARGIN = Span/(denominator-1)时 才能这么写         span=int(span)        y=FractionSlider.YMARGIN-0.5        # triangle=[QPointF(value*span,y),        #           QPointF(value*span+2*FractionSlider.XMARGIN,y),        #           QPointF(value*span+FractionSlider.XMARGIN,y+fm.height())]        #确定三角形中间那个点的位置        x=FractionSlider.XMARGIN+value*span        # 确定三角形上边长度/2的长度        trianglewidth=segWidth-indent        #找出围的三角形的点        triangle=[QPointF(x-trianglewidth,y),QPointF(x+trianglewidth,y),QPointF(x,y+fm.height())]        painter.setPen(Qt.yellow)        painter.setBrush(Qt.darkYellow)        painter.drawPolygon(QPolygonF(triangle))if __name__=='__main__':    import sys    app=QApplication(sys.argv)    form=QDialog()    sliderLabel=QLabel('&Fraction')    slider=FractionSlider(denominator=12)    sliderLabel.setBuddy(slider)    denominatorLabel=QLabel('&Denominator')    denominatorSpinBox=QSpinBox()    denominatorSpinBox.setRange(3,30)    denominatorSpinBox.setValue(slider.fraction()[1])    denominatorSpinBox.setAlignment(Qt.AlignRight|Qt.AlignCenter)    denominatorLabel.setBuddy(denominatorSpinBox)    numeratorLabel=QLabel('&Numberator')    numeratorLCD=QLCDNumber()    numeratorLCD.setSegmentStyle(QLCDNumber.Flat)    numeratorLabel.setBuddy(numeratorLCD)    #网格布局    layout=QGridLayout()     layout.addWidget(sliderLabel,0,0)    layout.addWidget(slider,0,1,1,5)    layout.addWidget(numeratorLabel,1,0)    layout.addWidget(numeratorLCD,1,1)    layout.addWidget(denominatorLabel,1,2)    layout.addWidget(denominatorSpinBox,1,3)    form.setLayout(layout)    def valueChanged(denominitor):        numerator=slider.decimal()*denominitor        slider.setFraction(numerator,denominitor)        numeratorLCD.display(numerator)    def dsp(num):        numeratorLCD.display(num)    #分母发生变化    denominatorSpinBox.valueChanged.connect(valueChanged)    #分子发生变化    slider.valueChanged.connect(dsp)    form.setWindowTitle('Fraction Slider')    form.show()    app.exec_()
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