bug: flet-map not show tile

[RezaErfani67]

Duplicate Check

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

Describe the bug

with version 0.84.0 not show any thing...
when i enter url_template address in chrom it opens:

https://tile.memomaps.de/tilegen/3/2/2.png

Code sample

Code

ft.Container(
                    content=
                    ft.SafeArea(
                        expand=True,
                        content=ftm.Map(
                            expand=True,
                            layers=[
                                ftm.TileLayer(
                                    url_template="https://tile.memomaps.de/tilegen/{z}/{x}/{y}.png",  # OpenStreetMap ok
                                    # url_template="https://tile.openstreetmap.org/3/2/2.png",
                                    on_image_error=lambda e: print(e),
                                ),
                            ],
                            on_init=lambda e: print(e),
                            initial_zoom=5,
                        ),
                    )

               ),

To reproduce

import flet as ft
import flet_map as ftm


def main(page: ft.Page):
    page.add(
        ft.SafeArea(
            expand=True,
            content=ftm.Map(
                expand=True,
                layers=[
                    ftm.TileLayer(
                        url_template="https://tile.memomaps.de/tilegen/{z}/{x}/{y}.png",
                        on_image_error=lambda e: print(f"TileLayer Error: {e.data}"),
                    ),
                ],
            ),
        )
    )


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

Expected behavior

No response

Screenshots / Videos

Captures

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Operating System

Windows

Operating system details

11

Flet version

0.84.0

Regression

I'm not sure / I don't know

Suggestions

No response

Logs

Logs

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Additional details

No response

[ndonkoHenri]

Thanks for the report. I was able to reproduce this when running the example in web mode.

The tile URL itself returns 200 image/png, but tile.memomaps.de does not send an Access-Control-Allow-Origin header. In Flet/Flutter web this causes the browser fetch to fail with errors like:

TileLayer Error: ClientException: Failed to fetch, uri=https://tile.memomaps.de/tilegen/13/4790/2760.png

Opening the tile URL directly in Chrome works because direct navigation is not subject to the same CORS checks.

The same MemoMaps tile layer renders correctly in a native desktop client, so this looks like a web/CORS compatibility issue with that tile server rather than a flet-map URL-template bug.

The workaround is to use a tile provider that allows cross-origin requests for web apps, for example OSM: "https://tile.openstreetmap.org/{z}/{x}/{y}.png". Will be doing the update for our map examples because they currently use this MemoMaps URL.