How to change the TKinter canvas line from dash to solid?

The Canvas widget is one of the most widely used widgets for graphical representation in a Tkinter application. To display a line in the Canvas widget, we can use the built-in library method create_line(x1, y1, x2, y2, **options).

We can specify the line type using the dash property. To change the line type from dash to solid dynamically, we can use the itemconfig() method. By passing an empty tuple () to the dash property, we can change the line from dash to solid.

Basic Example

Let's create a dashed line and change it to solid when a button is clicked ?

# Import the required libraries
from tkinter import *
from tkinter import ttk

# Create an instance of tkinter frame or window
win = Tk()

# Set the size of the tkinter window
win.geometry("700x350")

def update_line():
    canvas.itemconfig(line, dash=())

# Create a canvas widget
canvas = Canvas(win, width=400, height=300, bg="white")
canvas.pack(pady=20)

# Create a dashed line
line = canvas.create_line(100, 50, 300, 150, dash=(4, 2), width=5, fill="blue")

# Create a button to change the dash property of the line
button = ttk.Button(win, text="Change to Solid", command=update_line)
button.pack(pady=10)

win.mainloop()

Understanding the Dash Property

The dash parameter accepts different values ?

• dash=() − Creates a solid line
• dash=(5, 2) − Creates dashes of 5 pixels with 2 pixel gaps
• dash=(10, 5, 2, 5) − Creates alternating dash patterns

Interactive Example with Multiple Line Types

Here's a more comprehensive example that demonstrates switching between different line types ?

from tkinter import *
from tkinter import ttk

# Create main window
win = Tk()
win.geometry("800x400")
win.title("Canvas Line Types")

# Create canvas
canvas = Canvas(win, width=600, height=300, bg="white", relief=SUNKEN, borderwidth=2)
canvas.pack(pady=20)

# Create multiple lines with different styles
line1 = canvas.create_line(50, 50, 350, 50, dash=(8, 4), width=3, fill="red")
line2 = canvas.create_line(50, 100, 350, 100, dash=(12, 6, 3, 6), width=3, fill="green")
line3 = canvas.create_line(50, 150, 350, 150, dash=(5, 3), width=3, fill="blue")

# Add labels
canvas.create_text(400, 50, text="Line 1: dash=(8, 4)", anchor="w")
canvas.create_text(400, 100, text="Line 2: dash=(12, 6, 3, 6)", anchor="w")
canvas.create_text(400, 150, text="Line 3: dash=(5, 3)", anchor="w")

def make_solid():
    canvas.itemconfig(line1, dash=())
    canvas.itemconfig(line2, dash=())
    canvas.itemconfig(line3, dash=())

def make_dashed():
    canvas.itemconfig(line1, dash=(8, 4))
    canvas.itemconfig(line2, dash=(12, 6, 3, 6))
    canvas.itemconfig(line3, dash=(5, 3))

# Button frame
button_frame = Frame(win)
button_frame.pack(pady=10)

ttk.Button(button_frame, text="Make Solid", command=make_solid).pack(side=LEFT, padx=5)
ttk.Button(button_frame, text="Make Dashed", command=make_dashed).pack(side=LEFT, padx=5)

win.mainloop()

Key Points

• Use itemconfig() to modify line properties after creation
• Set dash=() for solid lines
• Use dash=(length, gap) for simple dashed patterns
• Store line IDs returned by create_line() for later modification

Conclusion

Use canvas.itemconfig(line_id, dash=()) to change a dashed line to solid. The dash property accepts tuples defining dash patterns, with an empty tuple creating solid lines.