How to make same event mean different things for different functions in tkinter?

dartigan 0
Viewed 53

I was wondering if it was possible to have the same event(like-R-click/R-mouse-press), mean different things for different functions :

For example : Moving an object on R-mouse press and also having the same event used for changing the shape of an object(by mouse press and drag).

My requirement : I am using a code which is used for snipping the area within, so basically it is a canvas which is being used as an overlay....

The problem i'm facing is that the overlay/snipping area never matches the image/pdf area. So currently i'm manually changing the canvas coordinates /Set_Geometry coordinates ,so that it matches the image/pdf (completely). This process takes too long. So i wanted to automate this process of changing and moving this overly /canvas by mouse. There are 2 specific operations i want :

  1. Being able to stretch the overlay/ canvas to match the image.
  2. Move this canvas around in the screen to place it exactly where the image is present.

Both of these operations i wanted to do using same the "b3-move" button. Here is the code :

import sys
from PyQt5 import QtWidgets, QtCore, QtGui
import tkinter as tk
from PIL import ImageGrab
import numpy as np
import cv2




class MyWidget(QtWidgets.QWidget):

    def __init__(self):
        super().__init__()
        root = tk.Tk()
        screen_width = root.winfo_screenwidth()
        screen_height = root.winfo_screenheight()
   
        x = screen_width/2 - dim[0]/2
        y = screen_height/2 - dim[1]/2
        self.setGeometry(x, y, dim[0], dim[1])
        self.setWindowTitle('Snipping')
        self.begin = QtCore.QPoint()
        self.end = QtCore.QPoint()
        self.setWindowOpacity(0.8)
        QtWidgets.QApplication.setOverrideCursor(
        QtGui.QCursor(QtCore.Qt.CrossCursor))
        self.setWindowFlags(QtCore.Qt.FramelessWindowHint)
        print('Capture the screen...')
        self.show()
           
    def paintEvent(self, event):
        qp = QtGui.QPainter(self)
        qp.setPen(QtGui.QPen(QtGui.QColor('black'), 3))
        qp.setBrush(QtGui.QColor(128, 128, 255, 128))
        qp.drawRect(QtCore.QRect(self.begin, self.end))
    

    def mousePressEvent(self, event):
        self.begin = event.pos()
        self.end = self.begin
        self.update()

    def mouseMoveEvent(self, event):
        self.end = event.pos()
        self.update()

    def mouseReleaseEvent(self, event):
        self.close()
        x1 = min(self.begin.x(), self.end.x())
        y1 = min(self.begin.y(), self.end.y())
        x2 = max(self.begin.x(), self.end.x())
        y2 = max(self.begin.y(), self.end.y())

        img = ImageGrab.grab(bbox=(x1, y1, x2, y2))
        img = cv2.cvtColor(np.array(img), cv2.COLOR_BGR2RGB)
        cv2.imshow('Captured Image', img)
        cv2.waitKey(0)
        cv2.destroyAllWindows()

        global s
        s = str(x1) +","+str(dim[1] - y1)+","+str(x2)+","+str(dim[1]- y2)
        print(s)
    

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    window = MyWidget()
    window.show()
    app.aboutToQuit.connect(app.deleteLater)
    sys.exit(app.exec_())

How can i do this?

tkinter-button pyqt tkinter python
1 Answers

You can define event pattern in tkinter and they have the form of <modifier-modifier-type-detail>.

So what you can do is to combine event modifier such as Button3 and types as Motion with each other, (e.g.) root.bind('<Button3-Motion>',button3motion)

An example can be found below:

import tkinter as tk

def button3press(event):
    print('right click')

def button3release(event):
    print('right click ended')

def button3motion(event):
    print('mouse move while right click')

root = tk.Tk()
root.bind('<ButtonPress-3>',button3press)
root.bind('<ButtonRelease-3>',button3release)
root.bind('<B3-Motion>',button3motion)
root.mainloop()
Thingamabobs0
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