PhiaUi.Components.AspectRatio (phia_ui v0.1.15)

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Utility component that maintains a fixed aspect ratio for any child content.

Use this component to display images, videos, maps, iframes, or any embed that must maintain a predictable width-to-height ratio regardless of its container width. Zero JavaScript — pure CSS.

How it works

The outer <div> uses the padding-top trick to enforce the aspect ratio:

padding-top: calc(1 / ratio * 100%)

Because padding percentages in CSS are calculated relative to the element's width, setting padding-top to 1/ratio * 100% creates a box whose height is always proportional to its width. The inner <div> is then absolutely positioned with inset: 0 to fill this space.

RatioFloatResulting padding-top
16:916/9~56.25%
4:34/3~75%
1:11.0100%
21:921/9~42.86%
9:169/16~177.78% (portrait)
3:23/2~66.67%

Examples

Responsive hero image (16:9)

<.aspect_ratio ratio={16 / 9}>
  <img src="/images/hero.jpg" alt="Mountain landscape" class="object-cover w-full h-full" />
</.aspect_ratio>
<.aspect_ratio ratio={4 / 3} class="rounded-lg overflow-hidden">
  <img src={@product.thumbnail} alt={@product.name} class="object-cover w-full h-full" />
</.aspect_ratio>

Embedded YouTube video (16:9)

<.aspect_ratio ratio={16 / 9}>
  <iframe
    src="https://www.youtube.com/embed/dQw4w9WgXcQ"
    title="Video player"
    frameborder="0"
    allow="autoplay; encrypted-media"
    allowfullscreen
    class="w-full h-full"
  />
</.aspect_ratio>

Square avatar or profile image (1:1)

<.aspect_ratio ratio={1.0} class="rounded-full overflow-hidden w-32">
  <img src={@user.photo} alt={@user.name} class="object-cover w-full h-full" />
</.aspect_ratio>

Portrait social card (9:16)

<.aspect_ratio ratio={9 / 16} class="max-w-xs">
  <div class="w-full h-full bg-gradient-to-b from-primary to-primary/80 p-6 flex flex-col">
    ...
  </div>
</.aspect_ratio>

Interactive map embed

<.aspect_ratio ratio={16 / 9} class="rounded-lg overflow-hidden border">
  <iframe
    src="https://maps.google.com/maps?q=New+York&output=embed"
    title="Location map"
    class="w-full h-full"
  />
</.aspect_ratio>

Notes

  • Always set class="w-full h-full object-cover" (or similar) on child <img> elements so they fill the constrained box without distortion.
  • The outer <div> is position: relative w-full — add width constraints via class (e.g. class="max-w-sm") to limit the component's width.
  • overflow-hidden must be on the outer container (via :class) for rounded corners to clip the child content.

Summary

Functions

aspect_ratio(assigns)

Renders a container that maintains a fixed aspect ratio.

Functions

aspect_ratio(assigns)

Renders a container that maintains a fixed aspect ratio.

The outer <div> uses padding-top to lock the ratio; the inner <div> uses position: absolute; inset: 0 so child content fills the full space.

Example

<.aspect_ratio ratio={16 / 9}>
  <img src="/poster.jpg" alt="Movie poster" class="h-full w-full object-cover" />
</.aspect_ratio>

Attributes

  • ratio (:float) - Aspect ratio expressed as width / height. Default 1.0 (square). Common values: 16/9, 4/3, 21/9, 9/16. Defaults to 1.0.
  • class (:string) - Additional CSS classes applied to the outer wrapper <div>. Use max-w-N, rounded-*, and overflow-hidden here. Defaults to nil.
  • Global attributes are accepted. HTML attributes forwarded to the outer <div> (e.g. data-*, aria-*).

Slots

  • inner_block (required) - Content to render inside the aspect-ratio-constrained space. Set class="w-full h-full" on child elements to fill the box.