Feature request: Improve scaling API to simplify zoom implementation in embedders #18076

[harshsbhat]

…in embedders #18076

This pull request introduces a significant enhancement to the scaling API by adding a center: [x, y] parameter to the increaseScale and decreaseScale functions. This new parameter allows for customization of the zoom center, eliminating the need for manual adjustment of scroll positions after zoom operations. Previously, zooming would always scroll to _location.top and _location.left, requiring additional calculations to ensure the correct zoom center. With this enhancement, developers can specify the exact zoom center, simplifying the implementation of zoom features and ensuring more predictable behavior across various positions and zoom levels within the viewer.

1. Added center: [x, y] parameter to increaseScale and decreaseScale functions.
2. Have NOT implemented the updated scale function.

[nicolo-ribaudo]

I'm not a maintainer of pdf.js, but if I were I would really dislike somebody just copy-pasting the issue text as a prompt for some LLM, copying the resulting code, and opening a pull request without neither reading nor understanding the changes they are submitting.

[Snuffleupagus]

Sorry, but this unfortunately does not appear to be a working patch.

First of all, there's a bunch of unrelated code changes which are also going to fail linting.
Secondly, the center parameter doesn't actually seem to do anything which renders this patch moot.
Finally, at lot of the comments seems redundant given the actual code. (And I don't think that we need updateScale since that's mostly code duplication.)

[harshsbhat]

I understand both of you @Snuffleupagus and @nicolo-ribaudo . I was just trying to work on some real repo for the first time. Of course, in the process, I took help from ChatGPT for some parts of the code. Thank you, guys, for your feedback, I will try to find some beginner-friendly issues on this repo. Sorry for wasting your time.

[harshsbhat]

@Snuffleupagus So as I mentioned in the pull request I decided to not add the updateScale function in the app.js. But forgot to delete it from the pdf_viewer.js. @nicolo-ribaudo Can you add a little more information on what needs to be added in my code?

[Snuffleupagus]

Unfortunately I don't believe that the referenced issue is a good beginner bug, even more so if you're trying to do development with the "help" of ChatGPT.

[harshsbhat]

Okay, thanks for that I guess @Snuffleupagus . I guess I should improve my development skills before trying to make my first open-source contribution