用pyqt5逐步绘画的正确方法

时间:2018-12-12 16:16:58

标签: python pyqt pyqt5 qpainter paintevent

我有一个基本上是圆形的小部件。我想逐步绘制它,所以我需要逐步绘制(imo)。

通过以下代码,我实现了我想要的。但是,有一个问题。我正在将新事件传递给paintEvent函数,因为如果不这样做,该图像将不会更新,直到一切都完成了,所以我什么都没有实现。< / p>

小部件代码

import sys
import time
from PyQt5.QtCore import Qt, QRect
from PyQt5.QtWidgets import QApplication, QWidget, QCheckBox, QDesktopWidget

from PyQt5.QtGui import QPen, QPainter, QPaintEvent, QConicalGradient, QColor, QBrush

class Circle(QWidget):

    def __init__(self, size, color):
        super().__init__()

        self.loadingAngle = 0
        self.width = 0
        self.color = color
        self.pixmap_opacity = 1

        self.resize(size, size);
        self.center()

        self.initUI()

    def initUI(self):

        self.width = 15
        self.loadingAngle = 0
        self.show()

    def center(self):
        qr = self.frameGeometry()
        cp = QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())

    def paintEvent(self, qevent):

        self.setWindowFlags(Qt.FramelessWindowHint)
        self.setAttribute(Qt.WA_TranslucentBackground)
        self.setStyleSheet("background:transparent;")

        drawingRect = QRect()
        drawingRect.setX(qevent.rect().x() + self.width)
        drawingRect.setY(qevent.rect().y() + self.width)
        drawingRect.setWidth(qevent.rect().width() - self.width * 2)
        drawingRect.setHeight(qevent.rect().height() - self.width * 2)

        painter = QPainter(self)
        painter.setRenderHint(QPainter.Antialiasing)

        gradient = QConicalGradient()
        gradient.setCenter(drawingRect.center())
        gradient.setAngle(90)
        gradient.setColorAt(1, QColor(0,0,0))
        gradient.setColorAt(0, QColor(self.color[0], self.color[1],self.color[2]))

        arcLengthApproximation = self.width + self.width / 3
        pen = QPen(QBrush(gradient), self.width)
        pen.setCapStyle(Qt.RoundCap)
        painter.setPen(pen)
        painter.drawArc(drawingRect, 90 * 16 - arcLengthApproximation, -self.loadingAngle * 16)
        #time.sleep(0.25)

        if self.loadingAngle < 360:
            self.loadingAngle += 1
            #self.paintEvent(QDrawEvent())
            self.paintEvent(QPaintEvent())

有问题的行

self.paintEvent(QPaintEvent())

此行会产生一些错误,但是即使有错误,我也会按照我的意愿做。

  1. 如果我将qevent从函数本身传递到此新调用,则图像不会像我之前说的那样得到更新。

  2. 如果我创建了这个新的QPaintEvent,它确实可以工作。但是,错误是:

  

回溯(最近通话最近一次):

     

文件“ /home/btc/Escritorio/SinestesiaRCB/Clases/Widget.py”,第68行,在   paintEvent self.paintEvent(QPaintEvent())

     

TypeError:参数与任何重载调用都不匹配:   QPaintEvent(QRegion):参数不足

     

QPaintEvent(QRect):参数不足

     

QPaintEvent(QPaintEvent):参数不足

     

QBackingStore :: endPaint()在后备存储绘制设备上用活动绘制程序调用

这些错误可能来自其他行,例如:

qevent.rect().x()

由于新事件是空事件。

所以基本上我的问题是,我应该如何做才能正确完成它,这意味着无误地实现我想要的东西

PS。我的意思是逐步地。完成此操作后,创建了几个小部件,每个小部件之后是一秒钟。

enter image description here

1 个答案:

答案 0 :(得分:1)

永远不要直接调用paintEvent,必须使用update()间接调用它。另一方面,如果您想经常被调用,在这种情况下,您应该使用QTimer或更好的QTimeLine。

import sys
from PyQt5 import QtCore, QtGui, QtWidgets

class Circle(QtWidgets.QWidget):
    def __init__(self, size, color):
        super().__init__()
        self._loading_angle = 0
        self.width = 0
        self.color = color
        self.pixmap_opacity = 1
        self.resize(size, size)
        self.setWindowFlags(QtCore.Qt.FramelessWindowHint)
        self.setAttribute(QtCore.Qt.WA_TranslucentBackground)
        self.setStyleSheet("background:transparent;")
        self.center()
        self.initUI()

        timeline = QtCore.QTimeLine(4000, self)
        timeline.setFrameRange(0, 360)
        timeline.frameChanged.connect(self.setLoadingAngle)
        timeline.start()

    def initUI(self):
        self.width = 15
        self.setLoadingAngle(0)
        self.show()

    def loadingAngle(self):
        return self._loading_angle

    def setLoadingAngle(self, angle):
        self._loading_angle = angle
        self.update()

    loadingAngle = QtCore.pyqtProperty(int, fget=loadingAngle, fset=setLoadingAngle)

    def center(self):
        qr = self.frameGeometry()
        cp = QtWidgets.QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())

    def paintEvent(self, event):
        painter = QtGui.QPainter(self)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)
        drawingRect  = QtCore.QRect(QtCore.QPoint(), self.rect().size() - 2*self.width*QtCore.QSize(1, 1))
        drawingRect.moveCenter(self.rect().center())

        gradient = QtGui.QConicalGradient()
        gradient.setCenter(drawingRect.center())
        gradient.setAngle(90)
        gradient.setColorAt(1, QtGui.QColor(0,0,0))
        gradient.setColorAt(0, self.color)
        arcLengthApproximation = self.width + self.width / 3
        pen = QtGui.QPen(QtGui.QBrush(gradient), self.width)
        pen.setCapStyle(QtCore.Qt.RoundCap)
        painter.setPen(pen)
        painter.drawArc(drawingRect, 90 * 16 - arcLengthApproximation, -self._loading_angle * 16)


if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Circle(400, QtGui.QColor("blue"))
    w.show()
    sys.exit(app.exec_())