Images with dimensions larger than 32,767 pixels cannot be used

If you try to use an image of 32,768 pixels or taller, Tiled crops it to exactly 32,767 pixels and won't show any more than that. I would suspect this also happens for excessively wide images.

I don't know whether it's better to remove this limitation or show an error when it happens, but silently cropping it seems quite bad.

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For what it's worth, in case you're wondering why on earth anyone would do this: I discovered the issue while trying to fit an entire RPGMaker tileset (A1-5, B, C, D, E) onto one tilesheet in such a way that tile IDs are exactly the same as in RPGMaker, while keeping all the autotiles neatly arranged. The only way to satisfy both conditions (as far as I can tell) is with a width of 8 tiles (768 pixels, assuming an MV/MZ tileset of 48x48 tiles). RPGMaker tile IDs go up to 8192, which would require the tilesheet to be 49,152 pixels tall. (This would thus be almost okay for RPGMaker XP tilesets, where it would only need to be 32,768 pixels high.)

Start by reproducing the issue in Tiled with an image at least 32,768 pixels tall, then trace the image loading or display path responsible for the 32,767-pixel crop. Check how excessively wide images behave as well. Done means oversized images no longer disappear past the limit silently: the limitation is removed or a clear error is shown.

Written by the indexing model from the issue text.