QGraphicsItem，如何在childs上面绘制元素？

Question

from PyQt5.QtWidgets import QGraphicsItem
from PyQt5.QtSvg import  QGraphicsSvgItem, QSvgRenderer
from PyQt5.QtCore import Qt, QRectF

class MyItem(QGraphicsItem):
    def __init__(self, parent ):
        super().__init__( parent = parent )

        self.textRect =  QRectF( 0,0,100,100 )

        self.SvgGItem = QGraphicsSvgItem(self)
        self.Svg_renderer = QSvgRenderer("./item.svg")
        self.SvgGItem.setSharedRenderer ( self.Svg_renderer )
        self.SvgGItem.setElementId( "1" )

    def paint(self, painter, option, widget):
        alignFlags = Qt.AlignLeft | Qt.AlignTop
        painter.drawText( self.textRect, alignFlags , "text" )

我希望文本在svg项目之上。例如，这段代码，真正的代码非常困难，但是相同。 setZValue（）在这种情况下不起作用，很明显。有一些方法或其他决定？

Answer 1

试试吧：

import sys
from PyQt5.QtCore    import *
from PyQt5.QtGui     import *
from PyQt5.QtWidgets import *
from PyQt5.QtSvg import  QGraphicsSvgItem, QSvgRenderer


class MyItem(QGraphicsItem):
    def __init__(self):
        super().__init__()
        self.x = 0
        self.y = 0
        self.w = 100
        self.h = 100
        self.width = 8
        self.text = "None"

        self.setFlags(MyItem.ItemIsSelectable | MyItem.ItemIsMovable)

    def boundingRect(self):  
        return QRectF(self.x, self.y, self.w, self.h)    

    def paint(self, painter, option, widget):  
        painter.setPen(QPen(Qt.blue, self.width)) 
        rec = self.boundingRect().adjusted(self.width  / 2, 
                                           self.width  / 2, 
                                           -self.width / 2, 
                                           -self.width / 2)
        painter.setBrush(Qt.yellow)
        painter.drawRect(rec)
        painter.setFont(QFont("Arial", 16))
        self.textRect =  QRectF( 0, 0, 100, 100 )
        alignFlags = Qt.AlignCenter  
        painter.drawText( self.textRect, alignFlags , "! text !" )


class MySvg(QGraphicsSvgItem):
    def __init__(self):
        super(MySvg, self).__init__('blank.svg')    

        self.setFlags(QGraphicsItem.ItemIsSelectable|
                      QGraphicsItem.ItemIsMovable)        


class GraphicsScene(QGraphicsScene):
    def __init__(self):
        super().__init__()
        self.setSceneRect(-200, -200, 400, 400)  
        self.fillScene()

    def fillScene(self): 
        test = MySvg()
        self.addItem(test)

        item = MyItem()
        self.addItem(item)

    def drawBackground(self, painter, rect):
        painter.setPen(QPen(Qt.green, 3)) 
        painter.drawRect(self.sceneRect())
        painter.setPen(QPen(Qt.red, 3))
        painter.drawText(0, 0, '0')
        painter.drawText(-200, -200, '-200')
        painter.drawText(200, 200, '200')


class Main(QWidget):
    def __init__(self):
        super(Main, self).__init__()

        self.scene = GraphicsScene()
        self.view  = QGraphicsView(self)        
        self.view.setScene(self.scene)

        hbox = QHBoxLayout()
        hbox.addWidget(self.view)
        self.setLayout(hbox)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Main()
    ex.show()
    sys.exit(app.exec_())