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Accepted
Ramil
Asked:2020-12-21 20:25:49 +0800 CST2020-12-21 20:25:49 +0800 CST

图像未显示在小部件上

  • 772

QScene 上的图像未显示在 QGraphicsView 上。还尝试使用 QLabel 但失败了。

如果不使用小部件，可以显示图像，但使用它后，QGraphicScene 或 QLabel 结果是空的，但文本显示在那里。请告诉我，可能是什么问题？

使用 QScene、QGraphicsView、QWidget 的非工作变体： 

  from PyQt5.QtGui import *
  from PyQt5.QtCore import QUrl
  from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest
  from PyQt5.QtWidgets import QApplication, QLabel, QWidget, QVBoxLayout, QGraphicsScene, QGraphicsView
  import sys

 class Widget(QWidget):

  def __init__(self):
     super().__init__()
     self.initUI()

  def initUI(self):
     self.setGeometry(50,50,500,500)
     url = "http://pp.vk.me/c627626/v627626428/be07/wbpWha0RqZ4.jpg"
     self.scene = QGraphicsScene()
     self.mainImage = QGraphicsView()
     self.nam = QNetworkAccessManager()
     self.nam.finished.connect(self.finishRequest)
     self.nam.get(QNetworkRequest(QUrl(url)))
     layout = QVBoxLayout()
     layout.addWidget(self.mainImage)
     self.setLayout(layout)
     self.show()

  def finishRequest(self, reply):
     img = QImage()
     img.loadFromData(reply.readAll())
     self.item = QGraphicsPixmapItem(QPixmap.fromImage(img))
     self.scene.addItem(self.item)
     self.scene.setSceneRect(img.rect())
     self.mainImage.setScene(self.scene)


  if __name__ == '__main__': 
     app = QApplication(sys.argv)
     ex = Widget()
     ex.show()

     sys.exit(app.exec_())

使用 QLabel、QWidget 的非工作变体：

from PyQt5.QtGui import *
from PyQt5.QtCore import QUrl
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest
from PyQt5.QtWidgets import QApplication, QLabel, QWidget, QVBoxLayout
import sys

class Widget(QWidget):

  def __init__(self):
    super().__init__()
    self.initUI()

  def initUI(self):
    url = "http://pp.vk.me/c627626/v627626428/be07/wbpWha0RqZ4.jpg"
    self.lbl = QLabel("loading...")
    self.lbl.setAutoFillBackground(True)
    nam = QNetworkAccessManager()
    nam.finished.connect(self.finishRequest)
    nam.get(QNetworkRequest(QUrl(url)))
    self.layout = QVBoxLayout()
    self.layout.addWidget(self.lbl)
    self.setLayout(self.layout)
    self.show()

  def finishRequest(reply):
    img = QImage()
    img.loadFromData(reply.readAll())
    self.lbl.setPixmap(QPixmap.fromImage(img))

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

使用 QLabel 但不使用 QWidget 的工作变体：

from PyQt5.QtGui import *
from PyQt5.QtCore import QUrl
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest
from PyQt5.QtWidgets import QApplication, QLabel

app = QApplication([])
url = "http://pp.vk.me/c627626/v627626428/be07/wbpWha0RqZ4.jpg"
lbl = QLabel("loading...")
nam = QNetworkAccessManager()

def finishRequest(reply):
    img = QImage()
    img.loadFromData(reply.readAll())
    lbl.setPixmap(QPixmap(img))

nam.finished.connect(finishRequest)
nam.get(QNetworkRequest(QUrl(url)))
lbl.show()
app.exec_()
python

1 个回答

  1. Best Answer

    我在函数中看到了问题finish_request，您在其中传递了一个参数 - reply，但是 python 中的对象方法总是采用第一个参数self- 指向类对象的指针，它的模拟将this在с++

    当我将您的代码插入 IDE (PyCharm) 时，她立即在该函数中突出显示她不知道其中的变量来自何处self，事实上，这是正确的。

    from PyQt5.QtGui import QPixmap
from PyQt5.QtCore import QUrl
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest
from PyQt5.QtWidgets import QApplication, QLabel, QWidget, QVBoxLayout


class Widget(QWidget):
    def __init__(self):
        super().__init__()

        self.lbl = QLabel("loading...")
        self.lbl.setAutoFillBackground(True)

        self.nam = QNetworkAccessManager()
        self.nam.finished.connect(self.finish_request)

        url = "http://pp.vk.me/c627626/v627626428/be07/wbpWha0RqZ4.jpg"
        self.nam.get(QNetworkRequest(QUrl(url)))

        layout = QVBoxLayout()
        layout.addWidget(self.lbl)

        self.setLayout(layout)

    def finish_request(self, reply):
        img = QPixmap()
        img.loadFromData(reply.readAll())

        self.lbl.setPixmap(img)


if __name__ == '__main__':
    app = QApplication([])

    w = Widget()
    w.show()

    app.exec()

    带场景：

    from PyQt5.QtGui import QPixmap
from PyQt5.QtCore import QUrl
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest
from PyQt5.QtWidgets import (
    QApplication, QWidget, QVBoxLayout, QGraphicsScene, 
    QGraphicsView, QGraphicsPixmapItem, QGraphicsTextItem
)


class Widget(QWidget):
    def __init__(self):
        super().__init__()

        self.scene = QGraphicsScene()
        self.scene.addItem(QGraphicsTextItem('loading...'))

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

        self.nam = QNetworkAccessManager()
        self.nam.finished.connect(self.finish_request)

        url = "http://pp.vk.me/c627626/v627626428/be07/wbpWha0RqZ4.jpg"
        self.nam.get(QNetworkRequest(QUrl(url)))

        layout = QVBoxLayout()
        layout.addWidget(self.view)

        self.setLayout(layout)

    def finish_request(self, reply):
        self.scene.clear()

        img = QPixmap()
        img.loadFromData(reply.readAll())

        item = QGraphicsPixmapItem(img)
        self.scene.addItem(item)


if __name__ == '__main__':
    app = QApplication([])

    w = Widget()
    w.show()

    app.exec()
    • 1

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