Alpha-channel storage issue in custom chained maps

Wojciech Rygielski shared this problem 4 months ago
Solved

I have configured a chained map in providers.xml file. All layers are PNGs with transparency. I use the map as an overlay.

Locus displays tiles from the chained map properly at first, but fails to do so on a second try (e.g. after I zoom out, and zoom in again). All transparent pixels are filled with black, making the map opaque (and effectively not very useful as an overlay). I'm able to temporarily fix this issue by clearing the cache, but the problem returns every time I display the same tile for the second time.

My guess would be that Locus properly handles the alpha-channel (transparency) of this map, but it doesn't properly save this alpha-channel in the cache? But perhaps there's some trick I can use to make it work?

Thank you.

Comments (4)

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Good day Wojciech,

is it possible to get some configuration for the test? If data needs to keep private, I may change this topic to a private ticket.

Jiří M. aka Menion

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Sure. This is part of my providers.xml file. The tiles are served only for Switzerland area. Use Layer 4 (id="20120") as an overlay over any other map (with 100% visibility).

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Good day Wojciech,

thank you for your bug report. Issue simulated and fixed so it will work in next version as expected. Only what will be needed is to clear a cache (context menu of the map in the list of online maps) of already downloaded tiles, because they are incorrectly stored in the map database. Thanks for understanding.

Jiří M. aka Menion

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Awesome!