Python PyQt:TypeError,同时按下按钮更改Circle的颜色

时间:2012-09-07 10:47:12

标签: python qt pyqt4 qpainter

我是Python新手,使用PyQt4开发Gui。我想在按下切换按钮的同时更改圆圈的颜色。但是我在插槽中收到了错误。

我的代码是:

import sys
from PyQt4.QtGui import *
from PyQt4.QtCore import *

class MyFrame(QWidget):
    def __init__(self, parent=None):
        QWidget.__init__(self)

        self.scene=QGraphicsScene(self)
        self.scene.setSceneRect(QRectF(0,0,245,245))
        self.bt=QPushButton("Press",self)
        self.bt.setGeometry(QRect(450, 150, 90, 30))
        self.bt.setCheckable(True)
        self.color = QColor(Qt.green)
        self.color1= QColor(Qt.magenta)
        self.show()
        self.connect(self.bt, SIGNAL("clicked()"), self.changecolor)

    def paintEvent(self, event=None):
        paint=QPainter(self)
        paint.setPen(QPen(QColor(Qt.magenta),1,Qt.SolidLine))
        paint.setBrush(self.color)
        paint.drawEllipse(190,190, 70, 70)
        paint.setPen(QPen(QColor(Qt.green),1,Qt.SolidLine))
        paint.setBrush(self.color1)
        paint.drawEllipse(300,300, 70, 70)

    def changecolor(self):
        if pressed:
         self.color = QColor(Qt.red)
         self.color1= QColor(Qt.blue)
        else:
         self.color=QColor(Qt.yellow)
         self.color1=QColor(Qt.gray)

        self.update()

app=QApplication(sys.argv)
f=MyFrame()
f.show()
app.exec_()

1 个答案:

答案 0 :(得分:3)

它的方式,它试图只用一个参数self来调用changecolor。我不完全确定你想要实现的目标。你的changecolor接受一个变量“paint”,但尝试使用self.paint,它不存在。所以也许你可以想一想,你可以通过调用QPainter来获取画家,并丢失一个名为“paint”的参数,如下所示:

def changecolor(self):
  paint = QPainter(self)
  paint.setBrush(QColor(Qt.red))
  paint.drawEllipse(190,190,70,70)
  self.update()

这会遇到以下错误:

QPainter::begin: Widget painting can only begin as a result of a paintEvent
QPainter::setBrush: Painter not active

告诉你,你只能在paintEvent中有绘画动作。一种解决方案是拥有一个类成员,例如self.color,用于保存圆圈所需的颜色。完整工作的代码如下:

import sys
from PyQt4.QtGui import *
from PyQt4.QtCore import *

class MyFrame(QWidget):
  def __init__(self, parent=None):
    QWidget.__init__(self)

    self.scene=QGraphicsScene(self)
    self.scene.setSceneRect(QRectF(0,0,245,245))
    self.bt=QPushButton("Press",self)
    self.bt.setGeometry(QRect(450, 150, 90, 30))
    self.color = QColor(Qt.green)
    self.show()
    self.connect(self.bt, SIGNAL("clicked()"), self.changecolor)

  def paintEvent(self, event=None):
    paint=QPainter(self)
    paint.setPen(QPen(QColor(Qt.red),1,Qt.SolidLine))
    paint.setBrush(self.color)
    paint.drawEllipse(190,190, 70, 70)

  def changecolor(self):
    self.color = QColor(Qt.red)
    self.update()

app=QApplication(sys.argv)
f=MyFrame()
f.show()
app.exec_()