Problem with Image rendering

[Orlangur777]

Question

Hi!
I'm testing flat and trying to write a simple program that renders an input expression to a graphic file using flex and matplotlib.

We accept a string with equation from the user (for example 'x+1=3'), render it to a png file and output it to the Image widget. So far everything is correct. But if we change the equation in the input widget and press the render button again, the Image widget content does not change. However, the new file is rendered correctly. But the widget does not show it.
Thanks in advance for your help!

Code sample

import flet as ft
import sympy as sp
import matplotlib.pyplot as plt
import matplotlib
matplotlib.use('Agg')

def main(page: ft.Page):
    page.window.width = 1280
    page.window.height = 720
    output_file = 'expression_output'
    rendered_image = ft.Image(src='expression_output.png')

    def render_latex(e):
        # Divide the equation into left and right parts
        try:
            left_side, right_side = equation_field.value.split('=')
            left_expr = sp.sympify(left_side.strip())
            right_expr = sp.sympify(right_side.strip())
            eq = sp.Eq(left_expr, right_expr)
        except Exception as e:
            print(f"Error processing equation: {e}")
            return

        latex_expr = sp.latex(eq)

        # Matplotlib rendering
        fig, ax = plt.subplots(figsize=(5, 2))
        ax.text(0.5, 0.5, f"${latex_expr}$", fontsize=18, ha='center', va='center', color='black')
        ax.axis('off')
        plt.savefig(output_file, bbox_inches='tight', pad_inches=0.1, transparent=True)
        plt.close(fig)
        print(f"Image saved as '{output_file}'")

        main_container.content.controls.append(rendered_image)
        page.update()
        main_container.content.controls.remove(rendered_image)

    # Text field
    equation_field = ft.TextField(
        label='Enter the equation',
        hint_text='Equation',
    )
    # Render button
    render_button = ft.ElevatedButton(
        text='Render',
        on_click=render_latex
    )
    # Main container
    main_container = ft.Container(
        content=ft.Column(
            controls=[
                equation_field, render_button
            ]
        )
    )

    page.add(main_container)


ft.app(target=main)

Error message

No response

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• I have searched for answers to my question both in the issues and in previous discussions.