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一、PyQt5绘画系统概述

PyQt5提供了强大的绘画功能，能够渲染矢量图形、图像以及基于轮廓字体的文本。无论是对现有小部件进行修改，还是创建自定义小部件，应用程序都需要绘图支持。PyQt5提供了丰富的绘图API，能够满足各种绘图需求。

二、QPainter绘画部件

QPainter是PyQt5中用于绘制的核心工具。它能够在小部件和其他绘画设备上执行低级绘图操作。无论是绘制简单的线条，还是复杂的图形，QPainter都能胜任。它通常在窗口的绘图事件paintEvent()中使用。

QPainter的使用流程如下：

三、绘图事件方法

绘图工作始终在paintEvent()方法中执行。QPainter的所有绘图方法需要在begin()和end()之间进行。具体来说：

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

四、PyQt5绘制文本

要在窗口中绘制文本，可以参考以下代码示例：

import sysfrom PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QColor, QFontfrom PyQt5.QtCore import Qtclass Example(QWidget):    def __init__(self):        super().__init__()        self.text = "Лев Николаевич Толстой\nАнна Каренина"        self.setGeometry(300, 300, 350, 300)        self.setWindowTitle('Drawing text')    def paintEvent(self, event):        qp = QPainter()        qp.begin(self)        self.drawText(event, qp)        qp.end()    def drawText(self, event, qp):        qp.setPen(QColor(168, 34, 3))        qp.setFont(QFont('Decorative', 10))        qp.drawText(event.rect(), Qt.AlignCenter, self.text)def main():    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())if __name__ == '__main__':    main()

五、PyQt5绘制点

要绘制多个随机点，可以参考以下代码示例：

import sysfrom PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainterfrom PyQt5.QtCore import Qtclass Example(QWidget):    def __init__(self):        super().__init__()        self.setGeometry(300, 300, 300, 190)        self.setWindowTitle('Points')    def paintEvent(self, e):        qp = QPainter()        qp.begin(self)        self.drawPoints(qp)        qp.end()    def drawPoints(self, qp):        qp.setPen(Qt.red)        size = self.size()        if size.height() <= 1:            return        for i in range(1000):            x = random.randint(1, size.width() - 1)            y = random.randint(1, size.height() - 1)            qp.drawPoint(x, y)def main():    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())if __name__ == '__main__':    main()

六、PyQt5颜色表达

PyQt5支持多种颜色表示方式，包括RGB和RGBA值。以下代码示例展示了如何使用不同的颜色来绘制矩形：

import sysfrom PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QColor, QBrushimport sysclass Example(QWidget):    def __init__(self):        super().__init__()        self.setGeometry(300, 300, 350, 100)        self.setWindowTitle('Colours')    def paintEvent(self, e):        qp = QPainter()        qp.begin(self)        self.drawRectangles(qp)        qp.end()    def drawRectangles(self, qp):        col = QColor(0, 0, 0)        col.setNamedColor('#d4d4d4')        qp.setPen(col)        qp.setBrush(QColor(200, 0, 0))        qp.drawRect(10, 15, 90, 60)        qp.setBrush(QColor(255, 80, 0, 160))        qp.drawRect(130, 15, 90, 60)        qp.setBrush(QColor(25, 0, 90, 200))        qp.drawRect(250, 15, 90, 60)def main():    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())if __name__ == '__main__':    main()

七、PyQt5画笔QPen

QPen是PyQt5中用于绘制图形边缘的工具。以下代码示例展示了如何使用不同笔样式绘制线条：

import sysfrom PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QPenfrom PyQt5.QtCore import Qtclass Example(QWidget):    def __init__(self):        super().__init__()        self.setGeometry(300, 300, 280, 270)        self.setWindowTitle('Pen styles')    def paintEvent(self, e):        qp = QPainter()        qp.begin(self)        self.drawLines(qp)        qp.end()    def drawLines(self, qp):        pen = QPen(Qt.black, 2, Qt.SolidLine)        qp.setPen(pen)        qp.drawLine(20, 40, 250, 40)        pen.setStyle(Qt.DashLine)        qp.setPen(pen)        qp.drawLine(20, 80, 250, 80)        pen.setStyle(Qt.DashDotLine)        qp.setPen(pen)        qp.drawLine(20, 120, 250, 120)        pen.setStyle(Qt.DotLine)        qp.setPen(pen)        qp.drawLine(20, 160, 250, 160)        pen.setStyle(Qt.DashDotDotLine)        qp.setPen(pen)        qp.drawLine(20, 200, 250, 200)        pen.setStyle(Qt.CustomDashLine)        pen.setDashPattern([1, 4, 5, 4])        qp.setPen(pen)        qp.drawLine(20, 240, 250, 240)def main():    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())if __name__ == '__main__':    main()

八、PyQt5画刷QBrush

QBrush是PyQt5中用于绘制图形内部的工具。以下代码示例展示了如何使用不同画刷风格绘制矩形：

import sysfrom PyQt5.QtWidgets import QWidget, QApplicationfrom PyQt5.QtGui import QPainter, QBrushfrom PyQt5.QtCore import Qtclass Example(QWidget):    def __init__(self):        super().__init__()        self.setGeometry(300, 300, 355, 280)        self.setWindowTitle('Brushes')    def paintEvent(self, e):        qp = QPainter()        qp.begin(self)        self.drawBrushes(qp)        qp.end()    def drawBrushes(self, qp):        brush = QBrush(Qt.SolidPattern)        qp.setBrush(brush)        qp.drawRect(10, 15, 90, 60)        brush.setStyle(Qt.Dense1Pattern)        qp.setBrush(brush)        qp.drawRect(130, 15, 90, 60)        brush.setStyle(Qt.Dense2Pattern)        qp.setBrush(brush)        qp.drawRect(250, 15, 90, 60)        brush.setStyle(Qt.DiagCrossPattern)        qp.setBrush(brush)        qp.drawRect(10, 105, 90, 60)        brush.setStyle(Qt.Dense5Pattern)        qp.setBrush(brush)        qp.drawRect(130, 105, 90, 60)        brush.setStyle(Qt.Dense6Pattern)        qp.setBrush(brush)        qp.drawRect(250, 105, 90, 60)        brush.setStyle(Qt.HorPattern)        qp.setBrush(brush)        qp.drawRect(10, 195, 90, 60)        brush.setStyle(Qt.VerPattern)        qp.setBrush(brush)        qp.drawRect(130, 195, 90, 60)        brush.setStyle(Qt.BDiagPattern)        qp.setBrush(brush)        qp.drawRect(250, 195, 90, 60)def main():    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())if __name__ == '__main__':    main()

九、PyQt5贝塞尔曲线

PyQt5支持绘制贝塞尔曲线。以下代码示例展示了如何使用QPainterPath绘制贝塞尔曲线：

import sysfrom PyQt5.QtGui import QPainter, QPainterPathfrom PyQt5.QtWidgets import QWidget, QApplicationclass Example(QWidget):    def __init__(self):        super().__init__()        self.setGeometry(300, 300, 380, 250)        self.setWindowTitle('Bézier curve')    def paintEvent(self, e):        qp = QPainter()        qp.begin(self)        qp.setRenderHint(QPainter.Antialiasing)        self.drawBezierCurve(qp)        qp.end()    def drawBezierCurve(self, qp):        path = QPainterPath()        path.moveTo(30, 30)        path.cubicTo(30, 30, 200, 350, 350, 30)        qp.drawPath(path)def main():    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())if __name__ == '__main__':    main()

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