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brendan-duncan / image

Dart Image Library for opening, manipulating, and saving various different image file formats.
MIT License
1.14k stars 255 forks source link

Foolproof didn't work #651

Closed ServOKio closed 2 months ago

ServOKio commented 2 months ago

Let's just imagine that the user renamed .jpg file to .png and then decodeImageFile -> findDecoderForNamedImage gives an incorrect response and I get an error

Maybe it's better to try to read mine?

brendan-duncan commented 2 months ago

I don't know what "mine" is, but decodeImageFile will first attempt to decode the image based on the extension of the filename, and if that doens't work out, it will try to decode it via decodeImage, which just iterates through all of the decoders trying to find one that will work.

ServOKio commented 2 months ago

🤷‍♂️ It looks like "decodeImageFile" can't find it on its own, but if you specify the decoder, yes, everything works

321312312

findDecoderForNamedImage finds the PngDecoder, but it is incorrect

brendan-duncan commented 2 months ago

You could also use decodeImage, which is probably on par with lookupMimeType for performance, and is what decodeImageFile uses when the expected decoder fails. I don't know why decodeImageFile isn't falling back to PNG as the attempted JPG decoder failed, unless you're using an older version of the library before that change went in.

brendan-duncan commented 2 months ago

findDecoderForNamedImage is just a niave name based lookup, it doesn't try to actually ensure the decoder is valid for the actual image data. I should probably have skipped adding these functions. People aren't very good about naming files.

ServOKio commented 2 months ago

You could also use decodeImage, which is probably on par with lookupMimeType for performance, and is what decodeImageFile uses when the expected decoder fails. I don't know why decodeImageFile isn't falling back to PNG as the attempted JPG decoder failed, unless you're using an older version of the library before that change went in.

That's right, I'm on version 4.1.7, decodeImageFile sees that the file name ends in png and decodes as png, but it's actually jpg so...yes

Anyway, thanks a lot, good luck 👋