How to add a pixmap drawn in QGraphicsItem to QGraphicsScene?

Question

How to add a pixmap drawn in QGraphicsItem to QGraphicsScene in the following example?

#!/usr/bin/env python

from PyQt5.QtCore import QRectF, Qt
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QApplication, QGraphicsItem, QGraphicsView, QGraphicsScene, QMainWindow

class TicTacToe(QGraphicsItem):
    def __init__(self, helper):
        super(TicTacToe, self).__init__()

        self.mypixmap = QPixmap("exit.png")

    def paint(self, painter, option, widget):
        painter.setOpacity(1)
        painter.drawPixmap(0,0, 300, 300, self.mypixmap)


    def boundingRect(self):
        return QRectF(0,0,300,300)


class MyGraphicsView(QGraphicsView):
    def __init__(self):
        super(MyGraphicsView, self).__init__()
        scene = QGraphicsScene(self)

        self.tic_tac_toe = TicTacToe(self)

        scene.addItem(self.tic_tac_toe)

        self.setScene(scene)

        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)


class Example(QMainWindow):    
    def __init__(self):
        super(Example, self).__init__()

        self.y = MyGraphicsView()
        self.setCentralWidget(self.y)

if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    w = Example()
    w.show()
    sys.exit(app.exec_())

Sorry, the question isn't clear to me. What is the issue with your code? What is the goal you are trying to achieve? Can you please give us more details? — Sergio Monteleone, Apr 16 '18 at 10:59
I need to draw on a pixmap with painter, zoom the picture, and add scrollbars to it. That's the purpose. @S.Monteleone — Aquarius_Girl, Apr 16 '18 at 11:02
@Aquarius_Girl. Why aren't you using [QGraphicsPixmapItem](https://doc.qt.io/qt-5/qgraphicspixmapitem.html)? — ekhumoro, Apr 16 '18 at 16:50
@ekhumoro if I use qgraphicspixmapitem then will I be able to include the drawn pixmap in scene? — Aquarius_Girl, Apr 17 '18 at 00:11
@Aquarius_Girl. You don't ned to draw anything - it does all that for you. — ekhumoro, Apr 17 '18 at 00:15
@ekhumoro Please see update. How do I add that drawn pixmap in the QGraphicsView class? — Aquarius_Girl, Apr 17 '18 at 03:20

score 0 · Accepted Answer · answered Apr 16 '18 at 18:12

Try it:

Drag and drop image, Enlarge Image -> Qt.Key_Right, Reduce image <- Qt.Key_Left.

from PyQt5.QtCore    import (QLineF, QPointF, QRectF, 
                             pyqtSignal, QStandardPaths, Qt)
from PyQt5.QtGui     import (QIcon, QBrush, QColor, QPainter, QPixmap)
from PyQt5.QtWidgets import (QAction, QMainWindow, QApplication, 
                             QGraphicsObject,
                             QGraphicsView, QGraphicsScene, QGraphicsItem,
                             QGridLayout, QVBoxLayout, QHBoxLayout, 
                             QFileDialog, QLabel, QLineEdit, QPushButton)
from PyQt5.QtOpenGL  import QGLFormat 

class MyGraphicsView(QGraphicsView):
    backgroundColor = QColor(28, 31, 34)     # Background color
    def __init__(self):
        super(MyGraphicsView, self).__init__()

        self.resize(800, 600)
        self.setBackgroundBrush(self.backgroundColor)
        self.setCacheMode(self.CacheBackground)
        self.setRenderHints(
            QPainter.Antialiasing | QPainter.TextAntialiasing | QPainter.SmoothPixmapTransform)
        if QGLFormat.hasOpenGL():
            self.setRenderHint(QPainter.HighQualityAntialiasing)
        self.setViewportUpdateMode(self.SmartViewportUpdate)
        self._scene = QGraphicsScene(-400, -300, 800, 600, self)
        self.setScene(self._scene)            
        self._itemImage = None

    def keyReleaseEvent(self, event):
        """ Button processing event """
        self._scaleImage(event)
        super(MyGraphicsView, self).keyReleaseEvent(event)

    def closeEvent(self, event):
        """ Clear all items in the scene when the window is `closed` """
        self._scene.clear()
        self._itemImage = None
        super(MyGraphicsView, self).closeEvent(event)

    def _scaleImage(self, event):
        """ Image zoom operation """
        if not self._itemImage:
            return
        scale = self._itemImage.scale()
        if event.key() == Qt.Key_Right:             
            # Enlarge Image -> Qt.Key_Right 
            if scale >= 0.91:
                return
            self._itemImage.setScale(scale + 0.1)
        elif event.key() == Qt.Key_Left:            
            # Reduce image <- Qt.Key_Left
            if scale <= 0.11:
                return
            self._itemImage.setScale(scale - 0.1)


    def loadImage(self):
        path, _ = QFileDialog.getOpenFileName(
            self, 'Please select an image', 
            QStandardPaths.writableLocation(QStandardPaths.DesktopLocation), 
            'Image(*.jpg *.png)')
        if not path:
            return
        if self._itemImage:
            # Delete previous item
            self._scene.removeItem(self._itemImage)
            del self._itemImage
        self._itemImage = self._scene.addPixmap(QPixmap(path))
        self._itemImage.setFlag(QGraphicsItem.ItemIsMovable)
        self._itemImage.setScale(0.1)         # Default load factor

        size = self._itemImage.pixmap().size()
        # Adjust the image in the middle
        self._itemImage.setPos(
            -size.width() * self._itemImage.scale() / 2,
            -size.height() * self._itemImage.scale() / 2
        )        


if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)

    w   = MyGraphicsView()
    w.show()
    ww = QPushButton('Select a file', clicked=w.loadImage)
    ww.show()    

    sys.exit(app.exec_())

How to add a pixmap drawn in QGraphicsItem to QGraphicsScene?

1 Answers1