Using Tkinter inside function not working - Printable Version +- Python Forum (https://python-forum.io) +-- Forum: Python Coding (https://python-forum.io/forum-7.html) +--- Forum: GUI (https://python-forum.io/forum-10.html) +--- Thread: Using Tkinter inside function not working (/thread-31603.html) |
Using Tkinter inside function not working - Ensaimadeta - Dec-22-2020 Hello all, With the help of some users in different forums I have get this far, but facing a new challenge in my way to making my first real world GUI, I hope some expert in tkinter can help. Needless to say that I am a novice in Python... I have made a device with the following structure:
What the system should do is: the Arduino is running a firmware to read the presence sensors and determine a position with a set of coordinates (x;y) and prints them through the Serial port (USB) in a line. The Raspberry running my Python code gets the information from the Serial port and breaks the line into 2 coordinates again. Then the program is supposed to paint a red rectangle if the coordinates are within the area defined, corresponding to 4 areas in the background image of the GUI. I am using Tkinter for this as it looked pretty easy for me to make the main window, put a background image and paint rectangles, but the reality is that I am finding that when I run the functions of painting the rectangles it looks like Tkinter “is not present” somehow (sorry for my lack of knowledge in explaining the issue). The code is this (and the error below): from serial import * from tkinter import * import time root = Tk() root.geometry("1280x800") root.attributes('-fullscreen',True) bg = PhotoImage(file = "/home/pi/Pictures/SCREEN2.png") canvas = Canvas( root, width = 1280, height = 800) canvas.pack(fill = "both", expand = True) canvas.create_image( 0, 0, image = bg, anchor = "nw") serialPort = "/dev/ttyUSB0" ser = Serial(serialPort, 9600, timeout=0) ser.flush() def split_coords(astring): a, b = astring.split(';') a = int(a) b = int(b) return (a, b) def paintRectangle1(): canvas.create_rectangle(200, 120, 400, 220, fill='red') time.sleep(0.3) def paintRectangle2(): canvas.create_rectangle(600, 120, 800, 220, fill='red') time.sleep(0.3) def paintRectangle3(): canvas.create_rectangle(200, 260, 400, 360, fill='red') time.sleep(0.3) def paintRectangle4(): canvas.create_rectangle(600, 260, 800, 360, fill='red') time.sleep(0.3) root.mainloop() while True: if ser.in_waiting> 0: line = ser.readline().decode('utf-8').rstrip() x, y = split_coords(line) print("x:", x, "- y:", y) if (19 < x < 60) and (20 < y < 40): print("OK button1") paintRectangle1() if (68 < x < 110) and (20< y < 40): print("OK button2") paintRectangle2() if (19 < x < 60) and (45 < y < 80): print("OK button3") paintRectangle3() if (68 < x <110) and (45 < y < 80): print("OK button4") paintRectangle4() #else: #paint the backgrand image again after the 0.3 seconds defined into the paintRectangle functionThe error that this code throws: As can be seen, the program goes into the paintRectangle after reading the coordinates, but it does not "understand" the canvas operation.I really don’t know what I should do to “get the mainframe inside the def statements” to make this work. Does anyone have an idea of what I am doing wrong? Thanks in advance. Joan. RE: Using Tkinter inside function not working - iMuny - Dec-22-2020 the canvas object you created is not visible to the paintRectangle[1-4] methods due to being out of scope of the subject methods, you can either adopt an object oriented approach to the above problem or you can pass an instance of the canvas object when you call the paintRectangle[1-4] methods, def paintRectangle1(canvas_ref): canvas_ref.create_rectangle(200, 120, 400, 220, fill='red') time.sleep(0.3) def paintRectangle2(canvas_ref): canvas_ref.create_rectangle(600, 120, 800, 220, fill='red') time.sleep(0.3) def paintRectangle3(canvas_ref): canvas_ref.create_rectangle(200, 260, 400, 360, fill='red') time.sleep(0.3) def paintRectangle4(canvas_ref): canvas_ref.create_rectangle(600, 260, 800, 360, fill='red') time.sleep(0.3)and you can call the methods like canvas = Canvas( root, width = 1280, height = 800) if (19 < x < 60) and (20 < y < 40): print("OK button1") paintRectangle1(canvas) if (68 < x < 110) and (20< y < 40): print("OK button2") paintRectangle2(canvas) if (19 < x < 60) and (45 < y < 80): print("OK button3") paintRectangle3(canvas) if (68 < x <110) and (45 < y < 80): print("OK button4") paintRectangle4(canvas) RE: Using Tkinter inside function not working - Ensaimadeta - Dec-22-2020 Hello iMuny, thanks for your suggestion. I have done as you suggested and still no luck... This is how it looks now: from serial import * from tkinter import * import time root = Tk() root.geometry("1280x800") root.attributes('-fullscreen',True) bg = PhotoImage(file = "/home/pi/Pictures/SCREEN2.png") canvas = Canvas( root, width = 1280, height = 800) canvas.pack(fill = "both", expand = True) canvas.create_image( 0, 0, image = bg, anchor = "nw") serialPort = "/dev/ttyUSB0" ser = Serial(serialPort, 9600, timeout=0) ser.flush() def split_coords(astring): a, b = astring.split(';') a = int(a) b = int(b) return (a, b) def paintRectangle1(canvas_ref): print("entered Rect 1") canvas_ref.create_rectangle(207, 151, 620, 374, fill='red') time.sleep(0.3) def paintRectangle2(canvas_ref): print("entered Rect 2") canvas_ref.create_rectangle(600, 120, 800, 220, fill='red') time.sleep(0.3) def paintRectangle3(canvas_ref): print("entered Rect 3") canvas_ref.create_rectangle(200, 260, 400, 360, fill='red') time.sleep(0.3) def paintRectangle4(canvas_ref): print("entered Rect 4") canvas_ref.create_rectangle(600, 260, 800, 360, fill='red') time.sleep(0.3) root.mainloop() while True: if ser.in_waiting> 0: line = ser.readline().decode('utf-8').rstrip() x, y = split_coords(line) print("x:", x, "- y:", y) canvas = Canvas( root, width = 1280, height = 800) if (x>19) and (x<60) and (y>20) and (y<40): print("OK button1") paintRectangle1(canvas) if (x>68) and (x<110) and (y>20) and (y<40): print("OK button2") paintRectangle2(canvas) if (x>19) and (x<60) and (y>45) and (y<80): print("OK button3") paintRectangle3(canvas) if (x>68) and (x<110) and (y>45) and (y<80): print("OK button4") paintRectangle4(canvas) ''' else: canvas.create_image( 0, 0, image = bg, anchor = "nw") '''and the error...
RE: Using Tkinter inside function not working - deanhystad - Dec-23-2020 Code located after "root.mainloop()" is not going to execute until you close the root window. But you can't just move your while loop ahead of "root.mainloop()" because that prevents tkinter from running. What you need to do is simultaneously let mainloop() run while processing data from your serial port. There is probably a framework for doing this kind of thing built into your Raspberry Pi libraries. Look at the serial port library for some way to call a function when data is available on the serial port. Failing that, look for some kind of scheduler that will execute a function periodically. You could always use the ".after" function from tkinter. In the example below I used root.after() in the random_rectangle() function to execute the function 10 times a second while letting mainloop() run at the same time. import random from tkinter import * import time rectangle = None root = Tk() root.geometry("200x200") canvas = Canvas( root, width = 1280, height = 800) canvas.pack(fill = "both", expand = True) canvas.create_image(0, 0, anchor = "nw") def random_rectangle(): global rectangle if rectangle is not None: canvas.delete(rectangle) x = random.randint(0, 200) // 50 * 50 y = random.randint(0, 200) // 50 * 50 rectangle = canvas.create_rectangle(x, y, x+50, y+50, fill='red') root.after(100, random_rectangle) random_rectangle() root.mainloop() print('This is not executed until you close the root window') RE: Using Tkinter inside function not working - darkv - Dec-03-2023 (Dec-22-2020, 07:11 PM)Ensaimadeta Wrote: Hello iMuny, thanks for your suggestion. same here. did you found the solution RE: Using Tkinter inside function not working - deanhystad - Dec-03-2023 You could use tkinter.after() to periodically run a function that checks for input on the serial port, or you can run the serial port loop in a separate thread. |