Downscale pasted PNG images based on metadata

[silverwind]

Some images like MacOS screenshots contain pHYs data which we can use to downscale uploaded images so they render in the same dppx ratio in which they were taken.

Before:

After:

[silverwind]

Dependency is removed 🎉.

I'm surprised how little code actually came out in the end. ~18 lines replacing over 100 lines from the dependency.

[silverwind]

This is ready. I checked the dropzone-attached images, they always render at 120x120, so downscaling them does not really make sense.

[silverwind]

Various refactors done, still ready for review.

[wxiaoguang]

A nit, TBH, I never saw a function returns a valid "struct" when it can't parse something, the literal meaning of "{width: 0}" for a non-png image seems confusing.

Maybe it should throw an exception or return null?

[silverwind]

Yeah this is something I thought about changing as well. Previously it was called imageInfo and in such a case it made sense to fall back to default values for non-png. I will at least move the type check out of the function, not sure about throwing, thought.

[silverwind]

I renamed it back to imageInfo as I could see it being extended with other types like webp oder jpg later.

I disagree about returning null or throwing, it would complicate the call site of the function unecessary, and right now because we always return a object the call site can stay compact and tidy.

Also I think it's good to have a static return structure which will make it a breeze to convert into Typescript later.

[wxiaoguang]

I disagree about returning null or throwing, it would complicate the call site of the function unecessary, and right now because we always return a object the call site can stay compact and tidy.

Well, I have never seen a widely-used framework does so. (not a blocker, just my thought)

[silverwind]

One example would be various React APIs where it's commonplace to return objects that are meant to be destructured. For example from https://docs.dndkit.com/api-documentation/draggable/usedraggable:

const {attributes, listeners, setNodeRef, transform} = useDraggable();

The object is just there to represent multiple named return values. Such functions should of course never return non-objects.

[wxiaoguang]

That's different. I guess useDraggable never parses something, and it never fails.

[silverwind]

These use* functions can also fail, but the point is they would throw instead of returning a non-object value (which would lead to a destructuring error at the caller).

I checked what is needed to return null in our case and its at least +6 lines for no real benefit.

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