In this article we will see how we can move the label within the window using arrow keys i.e when ever the arrow key(direction key) get pressed it moves towards that direction. For example when user press the Up arrow key the label will move upward similarly for other arrow keys label will change its position as well. Concept : We can change the position of the label by incrementing/decrementing the co-ordinate values of the label but do not increment or decrement if it reaches any end of the side below is the data given to do when each arrow key is pressed.
When Up arrow key is pressed : X Co-ordinate remain same, decrement the Y Co-ordinate When Down arrow key is pressed : X Co-ordinate remain same, increment the Y Co-ordinate When Left arrow key is pressed : Decrement X Co-ordinate, Y Co-ordinate remain same When Right arrow key is pressed : Increment X Co-ordinate, Y Co-ordinate remain same
Below is the edges restriction data so that label should remain in the window
For top edge the y- co-ordinate should be always greater than 0 For bottom edge the y- co-ordinate should be always less than height of window – height of label For left edge the x- co-ordinate should be always greater than 0 For right edge the x- co-ordinate should be always less than width of window – width of label
Implementation Steps : 1. Create a Main window 2. Create a label inside the main window 3. Add style sheet geometry to the label 4. Create a speed variable 5. Override the key press event 6. Inside the key press event get the current x and y co-ordinates of the label 7. And check which key key is pressed and check if side end is not reached then update the x and y co-ordinates with the help of move method by incrementing/decrementing speed value from them
Below is the implementation
Python3
# importing librariesfrom PyQt5.QtWidgets import *from PyQt5 import QtCore, QtGuifrom PyQt5.QtGui import *from PyQt5.QtCore import *import sysclass Window(QMainWindow): def __init__(self): super().__init__() # setting title self.setWindowTitle("Python ") # width of window self.w_width = 500 # height of window self.w_height = 500 # setting geometry self.setGeometry(100, 100, self.w_width, self.w_height) # calling method self.UiComponents() # showing all the widgets self.show() # speed variable self.speed = 15 # method for components def UiComponents(self): # creating a label self.label = QLabel(self) # label width self.l_width = 40 # label height self.l_height = 40 # setting geometry to the label self.label.setGeometry(200, 200, self.l_width, self.l_height) # setting stylesheet to the label self.label.setStyleSheet("QLabel" "{" "border : 4px solid darkgreen;" "background : lightgreen;" "}") # override the key press event def keyPressEvent(self, event): # get the current co-ordinates of the label # X Co-ordinate x = self.label.x() # Y Co-ordinate y = self.label.y() # if up arrow key is pressed if event.key() == Qt.Key_Up: # if top position is attained if y > 0: self.label.move(x, y - self.speed) # if down arrow key is pressed elif event.key() == Qt.Key_Down: # if bottom position is attained # for bottom point, bottom co-ordinate will be # height of window - height of label if y < self.w_height - self.l_height: self.label.move(x, y + self.speed) # if left arrow key is pressed elif event.key() == Qt.Key_Left: # if left end position is attained if x > 0: self.label.move(x - self.speed, y) # if down arrow key is pressed elif event.key() == Qt.Key_Right: # if right end position is attained # for right end point, right co-ordinate will be # width of window - width of label if x < self.w_width - self.l_width: self.label.move(x + self.speed, y)# create pyqt5 appApp = QApplication(sys.argv)# create the instance of our Windowwindow = Window()# start the appsys.exit(App.exec()) |
Output :
