Show chequerboard only if there is transparency and during cropping too #3174
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AWare
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Show chequerboard only if there is transparency and during cropping too
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What does this change?
In the Viewer, this makes chequerboard not show up underneath images with no transparency. We’ve noticed that sometimes there was a brief flash of it, even though it immediately hid behind the image fully. It keeps the chequerboard for images with transparency.
We decide on transparency based on the existence of
optimisedPng. This isn’t ideal, but we hidhasAlphaunder fileMetadata and we do not even have it there consistently for all images.optimisedPngisn’t a perfect transparency synonym, but it should get better, and in any case, it won’t ever not be there if there is transparency (it may be there where there isn’t, but that’s OK as far as chequerboard is concerned).Lastly, this permanently overrides cropper.js CSS to always show the chequerboard behind the image. We haven’t noticed a flash of it for opaque images, so no transparency check is performed here. There is this cropper.js option, but I thought we would want our chequerboard look to be consistent.
How can success be measured?
These changes will make Viewer look less glitchy (no useless flashes of chequerboard) and will bring us closer to always presenting images with transparency on a chequerboard background (at the cropping stage). Thumbnail generation is the last place where we bake transparent images onto a background.
Screenshots
Viewer
[current on the left, proposed on the right]
Cropping stage
[current on the left, proposed on the right]Tested?