Saving an image after painting on it

[benyeyeye]

What i am trying to do is be able to draw on an image (specifically rectangles) and then save the image. I have found the following code:

from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import sys


class Window(QMainWindow):

    def __init__(self):

        super().__init__()
        self.image = QImage("img.png")
        self.image.scaledToWidth(400)
        # self.showFullScreen()
        self.startPos = None
        self.rect = QRect()
        self.drawing = False

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton and not self.drawing:
            self.startPos = event.pos()
            self.rect = QRect(self.startPos, self.startPos)
            self.drawing = True
            self.update()

    def mouseMoveEvent(self, event):
        if self.drawing == True:
            self.rect = QRect(self.startPos, event.pos())
            self.update()

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drawing = False

    def paintEvent(self, event):

        pen = QPen()
        pen.setWidth(3)
        pen.setColor(QColor(255, 0, 0))

        brush = QBrush()
        brush.setColor(QColor(255, 0, 0))
        brush.setStyle(Qt.SolidPattern)

        painter = QPainter(self)
        painter.drawImage(0, 0, self.image)
        painter.setBrush(brush)
        painter.setPen(pen)
        if not self.rect.isNull():
            painter.drawRect(self.rect)
        painter.end()


app = QApplication(sys.argv)
window = Window()
window.show()
sys.exit(app.exec_())

From this forum post: https://discuss.python.org/t/if-mouse-button-event-draw-rectangle-pyqt5/6064/11

However when i try and save the image, it just saves the original without the rectangle. Also, it allows for drawing outside the boundaries of the image which i do not want

How can i fix these issues?

[SGaist]

Hi,

You have to paint on the QImage if you want these changes to be storable.

You can do that in the method that saves the image. Do the painting on a copy of it and save it after.

[benyeyeye]

@SGaist Hi, I'm not really sure how i would do that, can you point me in the right direction?

[SGaist]

Well:

1. create a copy of the image
2. create a QPainter on it
3. draw
4. call end
5. save the copy

[benyeyeye]

@SGaist Sorry but i have no idea how to call a qpainter on the image as well as creating a copy, can i have some actual code?

Appeciate the help

Just to add i understand what you're saying so you don't need to simplify it , just not how to implement it with pyqt

[SGaist]

For the copy, please read the class documentation. It's QImage::copy.

For painting on the QImage:

painter = QPainter(image)
# paint what you want
painter.end()

[snehalharshe]

This post is deleted!