Question

我已经编写了我的第一个自定义窗口小部件 - 一个用于显示后台任务进度的小状态指示灯。我做错了，因为当鼠标结束时，我反复继续发出以下错误，或者与包含自定义小部件的Qt窗口进行交互：

QPainter::begin: Paint device returned engine == 0, type: 2

应用程序不会崩溃，但会继续将此错误转储到std out。我对Qt相当新，并且已经四处寻找，试图找出如何解决这个问题无济于事。我希望有更多Qt经验的人能够通过正确的方式指导我使用paintEvent（）实现自定义小部件。我附上了以下代码：

from PySide import QtGui, QtCore


class LightWidget(QtGui.QLabel):

    def __init__(self,parent=None):
        super(LightWidget,self).__init__(parent)
        self.setPixmap(QtGui.QPixmap())
        self.setMinimumSize(15,15)
        self.setMaximumSize(15,15)
        self.set_fill_color(.6,.6,.6)
        self.set_line_color(0,0,0)
        self.set_line_width(1)

    def set_fill_color(self,r,b,g,a=1.0,hsv=False):
        ncolor=QtGui.QColor()
        if hsv:
            ncolor.setHsvF(r,g,b,a)
        else:
            ncolor.setRgbF(r,g,b,a)
        self._fill_color=ncolor

    def set_line_color(self,r,g,b,a=1.0,hsv=False):
        ncolor=QtGui.QColor()
        if hsv:
            ncolor.setHsvF(r,g,b,a)
        else:
            ncolor.setRgbF(r,g,b,a)
        self._line_color=(ncolor)

    def set_line_width(self,width):
        self._line_width=width

    def paintEvent(self,e):
        painter=QtGui.QPainter(self.pixmap())
        painter.begin(self)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)
        radx=self.width()*0.5
        rady=self.height()*0.5
        offset=self._line_width
        center=QtCore.QPoint(radx,rady)

        gradient = QtGui.QRadialGradient(center
                                         ,radx
                                         ,QtCore.QPointF(radx*0.5, rady*0.5))
        c_color = QtGui.QColor(0,0,0,0)
        c_color.setHsvF(self._fill_color.hueF()
                        ,self._fill_color.saturationF()
                        ,max(min(self._fill_color.valueF()*1.5,1.0),0) )
        o_color = QtGui.QColor(0,0,0,0)
        o_color.setHsvF(self._fill_color.hueF()
                        ,self._fill_color.saturationF()
                        ,max(min(self._fill_color.valueF()*.5,1),0))

        gradient.setColorAt(0, c_color)
        gradient.setColorAt(0.25, self._fill_color)
        gradient.setColorAt(1, o_color)

        pen=QtGui.QPen()
        pen.setColor(self._line_color)
        pen.setWidthF(self._line_width)
        brush = QtGui.QBrush(gradient)

        painter.setPen(pen)
        painter.setBrush(gradient)
        painter.drawEllipse(center,radx-offset,rady-offset)
        painter.end()


def test():
    form = QtGui.QWidget()
    wid = LightWidget(form)
    form.setWindowTitle('Status Light Widget')
    form.show()
    return form

def main():
    import sys
    app = QtGui.QApplication(sys.argv)
    window =test()
    sys.exit(app.exec_())



if __name__ == '__main__':
    main()

Answer 1

你将你画的内容混为一谈：

def paintEvent(self,e):
    # Here you start the painter on the pixmap
    painter=QtGui.QPainter(self.pixmap())
    # But here you start it on the widget proper
    painter.begin(self) 
    ...

事实是，您不需要任何像素图，并且您不需要从QLabel派生。从QWidget派生，直接在小部件上绘画：

def paintEvent(self,e):
    painter=QtGui.QPainter(self)
    # The begin() is redundant. Don't invoke it.
    ...

PySide Custom Widget w / Pixmap错误（QPainter :: begin：Paint device返回引擎== 0，键入：2）

1 个答案: