bug: animations do not work on flet-desktop

[begeansma019]

Duplicate Check

• I have searched the opened issues and there are no duplicates

Describe the bug

The animations don't work on flet desktop. When the animation is run it is not smooth its jittery.

Code sample

Code

import flet as ft


def main(page: ft.Page):
    def animate(e: ft.Event[ft.Button]):
        container.offset = ft.Offset(0, 0)
        container.update()

    page.add(
        ft.SafeArea(
            content=ft.Column(
                controls=[
                    container := ft.Container(
                        width=150,
                        height=150,
                        bgcolor=ft.Colors.BLUE,
                        border_radius=ft.BorderRadius.all(10),
                        offset=ft.Offset(x=-1.1, y=0),
                        animate_offset=ft.Animation(
                            duration=600,
                            curve=ft.AnimationCurve.BOUNCE_OUT,
                        ),
                    ),
                    ft.Button("Reveal!", on_click=animate),
                ],
            ),
        )
    )


if __name__ == "__main__":
    ft.run(main)

To reproduce

Run the program in a python ide in flet desktop view.

Expected behavior

The animation will not be smooth

Screenshots / Videos

Captures

[Upload media here]

Operating System

Windows

Operating system details

Windows 11 Home, version 25H2, OS build 26200.8875

Flet version

flet==0.86.5

Regression

Yes, it used to work in a previous Flet version (please specify the version in additional details)

Suggestions

The animations work fine in flet web so it narrows it down to just flet desktop

Logs

Logs

[Paste your logs here]

Additional details

Screen recording makes the animation look smooth when its not.

[begeansma019]

Additional finding: system restart restored animation performance

I found an important clue regarding the inconsistent animation behavior.

Before restarting Windows, Flet animations were noticeably jittery/inconsistent in both the desktop application and the web application. Some animations would stutter, jump to their final position, or fail to appear smooth.

After performing a full Windows restart, the same Flet code began animating smoothly on both desktop and web without any additional code changes.

This suggests that at least part of the problem may have been caused by the local system/rendering environment rather than exclusively by the Flet animation implementation.

One possible contributing factor is my usage pattern:

• The laptop is normally put to sleep every day rather than restarted.
• PyCharm is often left open for long periods.
• Flet/Python applications are frequently run from PyCharm.
• Chrome and other hardware-accelerated applications may also remain open across long sessions.

Windows sleep preserves operating-system state instead of performing a complete reboot. Microsoft also notes that kernel, driver, and service uptime can become quite long when systems repeatedly sleep/resume, and that this can expose driver-quality issues such as memory/resource leaks.

PyCharm can also maintain background processes, analysis tasks, running Python applications, and JVM memory usage during long sessions.

A possible sequence is therefore:

1. Windows remains running across many sleep/wake cycles.
2. PyCharm, Chrome, Python/Flet processes, and the graphics stack remain active or are repeatedly resumed.
3. Resource pressure or degraded GPU/display-driver/compositor state accumulates.
4. Flutter/Flet begins missing frame-rendering deadlines, making animations appear jittery or causing transitions to visually jump.
5. Restarting Windows terminates the existing processes and reinitializes the graphics driver, GPU state, Windows compositor, services, and application runtimes.
6. The same Flet animations become smooth again.

This is not confirmation that the Windows graphics driver or sleep/resume behavior is the root cause, but the restart result indicates that the issue is not necessarily caused entirely by the application's animation logic.

An additional observation supporting a rendering/presentation issue is that some animations that appeared jittery on the physical display could appear smooth when screen-recorded.

[ixenion]

Cant confirm that, at least in web.

Could you try to launch it in web?

import flet as ft

toggled: bool = False

def main(page: ft.Page):

    def animate(e: ft.Event[ft.Button]):
        global toggled
        toggled = not toggled
        if toggled:
            container.offset = ft.Offset(0, 0)
        else:
            container.offset = ft.Offset(-1.1, 0)
        container.update()

    page.add(
        ft.SafeArea(
            content=ft.Column(
                controls=[
                    container := ft.Container(
                        width=150,
                        height=150,
                        bgcolor=ft.Colors.BLUE,
                        border_radius=ft.BorderRadius.all(10),
                        offset=ft.Offset(x=-1.1, y=0),
                        animate_offset=ft.Animation(
                            duration=3500,
                            curve=ft.AnimationCurve.BOUNCE_OUT,
                        ),
                    ),
                    ft.Button("Reveal!", on_click=animate),
                ],
            ),
        )
    )


if __name__ == "__main__":
    ft.run(main)

And to start:

flet run -r main.py --web --port 8080 --host localhost

And open http://localhost:8080/

[ixenion]

Here is another thing: try to multiply animation duration by 100 and see.
Iv met a few tiems such behaviour, but dont remember exactly how it heals.