An image can overflow | Hacker News Reader

An image can overflow

master.dev

61 pointsibobev20 comments

I’ve seen this used before to add a credit that only appears when you save the image. You append the credit to the bottom of the image, then crop the image with CSS using a technique like this to hide the credit. Then when somebody saves the image, they get the whole thing and the credit appears.

Somewhat related, but back in the old days (maybe better to say early days) we used a different technique although purely for fun.

Yes, you can clip an image, but you can also scale an image, making it half the size of the original. The fun-part is that Netscape Navigator would render all the even lines, and Internet Explorer rendered the uneven lines (or the other way around). Making the picture vendor-specific :-) Since almost all the current browsers use the same render-engine (and if not probably the library) you can make you image bigger and hide some watermark in the non-rendered pixels.

> Since almost all the current browsers use the same render-engine (and if not probably the library) you can make you image bigger and hide some watermark in the non-rendered pixels.

Probably not because current browsers probably resize the image using an interpolation algorithm that considers all pixels instead of just throwing away half the data.

> Here is a demo where you can hover the image to show/hide the overflow:

Is something supposed to happen when I hover my mouse over the image? Because nothing happens. I'm using Firefox.

You should, I think, at that point be seeing a square image of a jellyfish inside a red square. The square should be containing the image. When you hover, it should reveal the rest of the jellyfish (the image itself is rectangular, and wider than it is tall).

(I'm also using FF, and it works for me.)

yeah, I see the square jellyfish image inside the red square, but nothing changes when I hover.

It's a schooner!

it's not a schooner...it's a sailboat

I'm using Safari on Mac and it also does not work for me.

I'm using Firefox dev, it overflows for me. Are you sure you didn't hover the earlier screenshot of the unhovered image inside the red square, as opposed to the image inside a codepen embed?

Definitely using codepen. I can manipulate the scaling and view the html and css windows and stuff. I'm not using the latest firefox version, but it's not like this is a new feature right?

Works for me on FF stable 148.0, 153.0.4, but does not with FF 145.

Okay, I've figured it out, thanks to the "test distros online" thingy to test version 145 and 148 as I previously mentioned.[0]

From Firefox 148 release notes for developers:[1]

> The overflow, overflow-x, and overflow-y CSS properties can now be used on replaced elements such as images, in the same way that they are used with other elements. Prior to this, replaced elements were always clipped to their bounding container. (Firefox bug 1999100).

[0]: https://news.ycombinator.com/item?id=49272986 [1]: https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Rel...

Broken link - it just says "403 Forbidden"

Still working for me, your IP or browser request might be flagged by their firewall or anti-bot protection

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