angular/components

CDK Overlay - Position Strategy with zoom css on parent

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#10,924 opened on Apr 19, 2018

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P4area: cdk/overlayhelp wanted

Description

Bug, feature request, or proposal:

If you are using the zoom CSS property to scale down UI elements the positioning of the CDK Overlay are calculated incorrectly.

What is the expected behavior?

Overlay positions properly as the non-zoomed styled div

What is the current behavior?

Overlay positions are calculated incorrectly when the zoom: 0.9 css property is on the parent container.

What are the steps to reproduce?

https://stackblitz.com/edit/cdk-overlay-zoom

What is the use-case or motivation for changing an existing behavior?

We have a Chrome only application that we use the zoom css property to scale down the UI. Using other methods of scaling does not work, so this is what we have to do.

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

Angular - 5.2.10 CDK - 5.2.5

Contributor guide

Tech stack
typescriptcss
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Angular CDKCSS zoomOverlay positioning
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
The issue provides a StackBlitz reproduction (https://stackblitz.com/edit/cdk overlay zoom) demonstrating incorrect overlay positioning when parent has zoom CSS. Investigate the CDK overlay's position strategy calculation, specifically how it handles CSS zoom. Look at the overlay position strategy source code in the Angular components repository. The comments may contain insights from maintainers. A possible fix could involve accounting for the zoom factor when calculating overlay coordinates.