自定义控件

PyQt5有丰富的组件，但是肯定满足不了所有开发者的所有需求，PyQt5只提供了基本的组件，像按钮，文本，滑块等。如果你还需要其他的模块，应该尝试自己去自定义一些。

自定义组件使用绘画工具创建，有两个基本方式：根据已有的创建或改进；通过自己绘图创建。

Burning widget

这个组件我们会在Nero，K3B，或者其他CD/DVD烧录软件中见到。

#!/usr/bin/python3
# -*- coding: utf-8 -*-

"""
ZetCode PyQt5 tutorial 

In this example, we create a custom widget.

Author: Jan Bodnar
Website: zetcode.com 
Last edited: August 2017
"""

from PyQt5.QtWidgets import (QWidget, QSlider, QApplication, 
    QHBoxLayout, QVBoxLayout)
from PyQt5.QtCore import QObject, Qt, pyqtSignal
from PyQt5.QtGui import QPainter, QFont, QColor, QPen
import sys

class Communicate(QObject):

    updateBW = pyqtSignal(int)


class BurningWidget(QWidget):

    def __init__(self):      
        super().__init__()

        self.initUI()


    def initUI(self):

        self.setMinimumSize(1, 30)
        self.value = 75
        self.num = [75, 150, 225, 300, 375, 450, 525, 600, 675]


    def setValue(self, value):

        self.value = value


    def paintEvent(self, e):

        qp = QPainter()
        qp.begin(self)
        self.drawWidget(qp)
        qp.end()


    def drawWidget(self, qp):

        MAX_CAPACITY = 700
        OVER_CAPACITY = 750

        font = QFont('Serif', 7, QFont.Light)
        qp.setFont(font)

        size = self.size()
        w = size.width()
        h = size.height()

        step = int(round(w / 10))


        till = int(((w / OVER_CAPACITY) * self.value))
        full = int(((w / OVER_CAPACITY) * MAX_CAPACITY))

        if self.value >= MAX_CAPACITY:

            qp.setPen(QColor(255, 255, 255))
            qp.setBrush(QColor(255, 255, 184))
            qp.drawRect(0, 0, full, h)
            qp.setPen(QColor(255, 175, 175))
            qp.setBrush(QColor(255, 175, 175))
            qp.drawRect(full, 0, till-full, h)

        else:

            qp.setPen(QColor(255, 255, 255))
            qp.setBrush(QColor(255, 255, 184))
            qp.drawRect(0, 0, till, h)


        pen = QPen(QColor(20, 20, 20), 1, 
            Qt.SolidLine)

        qp.setPen(pen)
        qp.setBrush(Qt.NoBrush)
        qp.drawRect(0, 0, w-1, h-1)

        j = 0

        for i in range(step, 10*step, step):

            qp.drawLine(i, 0, i, 5)
            metrics = qp.fontMetrics()
            fw = metrics.width(str(self.num[j]))
            qp.drawText(i-fw/2, h/2, str(self.num[j]))
            j = j + 1


class Example(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()


    def initUI(self):      

        OVER_CAPACITY = 750

        sld = QSlider(Qt.Horizontal, self)
        sld.setFocusPolicy(Qt.NoFocus)
        sld.setRange(1, OVER_CAPACITY)
        sld.setValue(75)
        sld.setGeometry(30, 40, 150, 30)

        self.c = Communicate()        
        self.wid = BurningWidget()
        self.c.updateBW[int].connect(self.wid.setValue)

        sld.valueChanged[int].connect(self.changeValue)
        hbox = QHBoxLayout()
        hbox.addWidget(self.wid)
        vbox = QVBoxLayout()
        vbox.addStretch(1)
        vbox.addLayout(hbox)
        self.setLayout(vbox)

        self.setGeometry(300, 300, 390, 210)
        self.setWindowTitle('Burning widget')
        self.show()


    def changeValue(self, value):

        self.c.updateBW.emit(value)        
        self.wid.repaint()


if __name__ == '__main__':

    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

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