BOTTOM Anchor ad alignment issue after resize fix

[dqureshiumar]

There was a recent fix merged for anchor ads that corrected the incorrect div resizing: PR #13701.

However, after this fix, another issue has appeared: once the anchor ad is resized, the ad alignment is stuck to the left side of the screen instead of maintaining proper centering or expected alignment. This issues appears only in Safeframe creatives.

This does not happen in case of TOP_ANCHOR.

Steps to Reproduce:

1. Implement an anchor ad unit with Prebid.js.
2. Ad should be rendered inside a Safeframe
3. Once the ad gets rendered, our resize function executes.
4. Observe that while the height/size updates correctly (fixed in PR Core: Fixing anchor ads rendering issue #13701), the ad div snaps to the left instead of staying centered.

Expected Behavior:

The anchor ad should remain correctly aligned (centered or as per original placement) after resizing.

References:

• Related PR: #13701
• Original issue on incorrect resizing: #7321

Screenshot:

Additional Question:

Can we support 1x1 creative resizing in the case of anchor ads?
Currently, this doesn't seem to happen. Is there a known limitation here, or something that needs to be explicitly enabled?

[dqureshiumar]

Hey @patmmccann , can you please have a look?

[dgirardi]

Hey @dqureshiumar ,

I can't quite reproduce this - but I do see issues. If I try it (see see https://jsfiddle.net/po34xjm9/2/) I don't see margins around the ad as you have in the screenshot. I also don't see any difference between top and bottom anchor.

However the slider itself is not rendered correctly depending on browser and viewport size, for example:

What you have looks more like if the resize didn't happen at all, and the creative is too narrow (here's with resizing disabled in code):

So I'm wondering what's different between my setup and yours. Do you have an example page? I'm especially curious about your top anchors if you say they're working correctly.

Can we support 1x1 creative resizing in the case of anchor ads?

Do you mean setting up a 1x1 line item / creative in GAM? My understanding is that it will pick only very particular sizes for anchors.

[dqureshiumar]

Hey @dgirardi ,

I have used your fiddle to replicate the issue,

Here are some of my findings:

Mobile: You will see the ad will be rendered in center, and as soon as our resize function executes our code makes the ad sticks to the left of the screen

Before Resizing Function Executes:

After Resizing Function Executes:

[dqureshiumar]

Do you mean setting up a 1x1 line item / creative in GAM? My understanding is that it will pick only very particular sizes for anchors.

Yes. just like we have support for Banner Creatives for 1x1 resizing, we also want anchor to support 1x1 rendering.
Reference - https://docs.prebid.org/adops/creative-considerations.html

[dqureshiumar]

I'm especially curious about your top anchors if you say they're working correctly.

Regarding this, I have noticed GPT's behavior that the ad is never visible before our resizing function kicks in

Screenshots:

Before resizing function executes - (Ad is not visible yet, for bottom anchor this is not the case)

After resizing function executes - (ad was not visible even after this function executes)

Once the resizing completes, now we can see the Ad Visible, so I believe our resizing is overridden by GPT, hence no impact on TOP_ANCHOR slots

[dqureshiumar]

Desktop

However the slider itself is not rendered correctly depending on browser and viewport size

I tested the Anchor ads for Desktop and here are my findings.

Once the Ad is rendered the Ad is sticked to the left side:

Iframe resizing - When Iframe was resized the Ad was aligned to center

GAM's div resizing - After resizing the GAM's div the Anchor Breaks

[dqureshiumar]

Hi @dgirardi , just following up on this issue to check if there are any updates or additional details needed from my side. Thanks!

[dgirardi]

hey @dqureshiumar, I apologize for the long delay - I'm now back on this.

I have posted #14107 that describes and tries to fix what I think are the issues with top and bottom anchors. Still trying to get GAM set up for side rails to test those as well.

I think something changed in the interim as now the anchor always starts open for me (no scrolling is necessary to activate it). I'd like to test it when it starts hidden but I can't find an option to toggle that, are you aware of any?