Overview
- What is TwicPics?
- What is TwicPics Components?
Installation
Setup
- Setting up TwicPics Components in your project
- Setup Options
Usage
Components properties
CSS variables
Default Breakpoints
Examples
Questions and feedback
Other frameworks
License

Overview

What is TwicPics?

TwicPics is a Responsive Media Service Solution (SaaS) that enables on-demand responsive image & video generation.

With TwicPics, developers only deal with high-resolution versions of their media while end-users receive optimized, perfectly sized, device-adapted versions delivered from a server close to them.

TwicPics acts as a proxy. It retrieves your master file — from your web server, cloud storage, or DAM — and generates a device-adapted version with best-in-class compression, delivered directly to the end-user from the closest available delivery point.

What is TwicPics Components?

TwicPics Components is a collection of web components that make it dead easy to unleash the power of TwicPics in your projects.

Whether you need to display a content image, showcase a short video, or ensure optimal performance with Large Contentful Paint (LCP) care, TwicPics Components has you covered.

Display a Critical Image

If you need to display critical images with art direction support, you can use the <TwicPicture> component.

It is a drop-in replacement for the standard picture tag and is based directly on the TwicPics API without additional effort.

<!-- Before -->
<picture>
  <source
    media="(min-width: 1280px)"
    srcset="wide-image.jpg, wide-image-2x.jpg 2x, wide-image-3x.jpg 3x"
  >
  <source
    media="(min-width: 768px)"
    srcset="squared-image.jpg, squared-image-2x.jpg 2x, squared-image-3x.jpg 3x"
  >
  <img
    srcset="portrait-image.jpg, portrait-image-2x.jpg 2x, portrait-image-3x.jpg 3x"
    src="portrait-image.jpg"
  >
</picture>

<!-- After -->
<TwicPicture
  src="your-master-image.jpg"
  ratio="3/4, @md 1, @xl 16/9"
/>

Display a Content Image

Suppose you want to display a pixel-perfect image with optimized Cumulative Layout Shift (CLS), Low-Quality Image Placeholder (LQIP), and lazy loading out of the box. In that case, you can use the <TwicImg> component.

It's a drop-in replacement for the standard img tag based on the TwicPics Script.

<!-- Before -->
<img src="https://example.com/your-image.jpg" />

<!-- After -->
<TwicImg src="your-image.jpg" />

Display a Video

For seamless playback of videos optimized with TwicPics, use the <TwicVideo> component. It's a sibling of <TwicImg> and serves as a drop-in replacement for the standard video tag.

<!-- Before -->
<video >
  <source src="https://example.com/your-video.mp4" type="video/mp4">
  <!-- ... other video sources ... -->
</video>

<!-- After -->
<TwicVideo src="your-video.mp4" />

Note

Discover our demonstrations and integration examples in our online demo project.

Installation

Add the @twicpics/components package to your project as a dev dependency:

# Using yarn
yarn add @twicpics/components -D

# Or using npm
npm install @twicpics/components --D

Setup

Note

You will need a TwicPics domain to initialize the package. Create an account for free to get your domain.

Setting up TwicPics Components in your `SvelteKit` project

Add the import part:

  // import TwicPics sveltekit components
  import { installTwicpics } from "@twicpics/components/sveltekit";
  // import TwicPics components css
  import "@twicpics/components/style.css";

And the configuration part (see Setup Options):

  installTwicpics( {
    // domain is mandatory
    "domain": "https://<your-domain>.twic.pics"
  } );

into the main layout of your SvelteKit project.

If you don't already have a layout that applies to all the pages of your application, simply create it by adding +layout.svelte file, right next to your entry point src/routes/+page.svelte.

src/routes/+layout.svelte

<script>
  // Here is an example of +layout.svelte file
  import { installTwicPics } from "@twicpics/components/sveltekit";
  import "@twicpics/components/style.css";
  installTwicPics( {
      "domain": `https://<your-domain>.twic.pics`,
  } );
</script>
<slot />

Setup Options

Option	Description	Type	Default
`anticipation`	TwicPics will lazy-load images by default. To avoid too abrupt a transition with elements appearing into view and then images very obviously loading afterwards, TwicPics will "anticipate" lazy loading by a factor of the actual viewport. This behavior is controlled by this setting.	`Number`	`0.2`
`breakpoints`	Customizes breakpoints value for responsive behavior.	`object`	`{ xs: 320, sm: 640, md: 768, lg: 1024, xl: 1280, '2xl': 1536 }`
`domain`	This is your very own TwicPics domain. Providing it is mandatory.	`String`
`env`	Can be `debug`, `offline` or `production`. When set to `debug`, a gray lightweight `svg` placeholder that displays its intrinsic dimensions is displayed in place of all medias targeted by their `src` value. When set to `offline`, these medias are replaced by a simple placeholder that allows to visualise their display area.	`String`	`"production"`
`handleShadowDom`	Must be set to `true` when using TwicComponents within a shadow DOM.	`boolean`	`false`
`maxDPR`	TwicPics will take the "Device Pixel Ratio" (`DPR`) of the current device into consideration when determining the sizes of images to load. By default, it will not take a `DPR` greater than `2` into consideration. If the `DPR` of the device is higher than `2`, TwicPics will assume it to be `2`. Using `maxDPR`, you can lower this limit down to `1` or be more permissive (for instance by setting it to `3` or `4`).	`Number`	`2`
`path`	Path to prepend to all src attributes. For instance, if path is `"some/folder"` then a src attribute set to `"image.jpg"` will be expanded into `"some/folder/image.jpg"`	`String`
`step`	To avoid requesting too may variants of the same image, TwicPics will round the width of images to the closest multiple of step. The height will then be computed in order to respect the original aspect ratio.	`Integer`	`10`

Usage

Import TwicPics Components such as TwicImg, TwicPicture, or TwicVideo into your template files.

Replace standard img, picture, or video tags with these components to enhance functionality and customization (see Components Properties).

Add the import part in the script section of your .svelte file:

<script>
  // this component will be used in instead of an img element.
  import { TwicImg } from "@twicpics/components/sveltekit";

  // this component will be used in instead of a `picture` element.
  import { TwicPicture } from "@twicpics/components/sveltekit";

  // this component will be used in instead of an video element.
  import { TwicVideo } from "@twicpics/components/sveltekit";
</script>

or

<script>
  // this component will be used in instead of an img element.
  import TwicImg from "@twicpics/components/sveltekit/TwicImg.svelte";

  // this component will be used in instead of a `picture` element.
  import TwicPicture from "@twicpics/components/sveltekit/TwicPicture.svelte";

  // this component will be used in instead of a video element.
  import TwicVideo from "@twicpics/components/sveltekit/TwicVideo.svelte";
</script>

then, use <TwicImg>, <TwicPicture> or <TwicVideo> instead of standard tags <img>, picture or <video> (see Components Properties).

Basic usage

<!-- component.svelte-->
<script>
  import TwicImg from "@twicpics/components/sveltekit/TwicImg.svelte";
</script>

<main>
  <TwicImg src="path/to/your/image"></TwicImg>
</main>

Bulk loading with TwicView

By default, <TwicImg> and <TwicVideo> will only start loading when they enter the viewport. But sometimes, you may want to load multiple assets in bulk instead of lazy loading them. This is where <TwicView> comes into play.

The <TwicView> component eagerly loads all of his <TwicImg> and <TwicVideo> children as soon as it enters the viewport (depending on your anticipation settings.)

For example, if you're building a carousel, you might want to bulk-load all images. In the following code, all three images will be loaded when TwicView comes into the viewport:

<TwicView>
  <TwicImg src="image1.jpg" />
  <TwicImg src="image2.jpg" />
  <TwicImg src="image3.jpg" />
</TwicView>

Critical Images

TwicPicture streamlines the use of picture elements and srcset attributes.

It operates independently of the TwicPics Script and dynamically generates source elements and srcset attributes from a single master file using variants transformed through the TwicPics API.

Resolution switching

The following examples illustrate how to serve different resolutions of the same image according to breakpoints and maxDPR defined in Setup Options.

<!-- Populate srcset and fallback with a list of squared variants -->
<TwicPicture src="your-lcp-image.jpg"></TwicPicture>

<!-- Populate srcset and fallback with a list of 16/9 variants -->
<TwicPicture
  src="your-lcp-image.jpg"
  ratio="16/9"
></TwicPicture>

<!-- eager disables lazy-loading and sets fetchpriority to high -->
<TwicPicture
  src="your-lcp-image.jpg"
  eager
></TwicPicture>

<!-- for best performances set sizes attribute is a best practice -->
<TwicPicture
  src="your-lcp-image.jpg"
  eager
  sizes="
    (min-width: 1000px) 33vw,
    96vw
  "
></TwicPicture>

For a comprehensive list of properties and detailed information, please refer to TwicPicture.

Art Direction

To achieve art direction, configure the following TwicPicture's properties following the mobile-first principle:

anchor
focus
mode
position
preTransform
ratio

The following examples illustrate how to serve various image variations based on distinct artistic directions and default breakpoint values:

<!--
  This will display a :
  squared variant (default ratio) for screen with a width < 1024 px
  4/3 variant for screen with a width >= 1024 px
  21/9 variant for screen with a width >= 1280 px
-->
<TwicPicture
  src="art.jpg"
  alt="Art Direction Example"
  ratio="
    @lg 4/3
    @xl 21/9
  "
/>

<!--
  This allows to change the focus point for screen with a width >= 1280 px
-->
<TwicPicture
  src="art.jpg"
  alt="Art Direction Example"
  ratio="
    @lg 4/3
    @xl 21/9
  "
  focus="@xl top"
/>

<!--
  This allows to set the cropping and focus point for small device
  and reset the setting for screen with a width >= 768 px
-->
<TwicPicture
  src="art.jpg"
  alt="Art Direction Example"
  preTransform="
    crop=1000x1000@0.25sx0.25s
    @md none
  "
  focus="
    0.5sx1s
    @md none
  "
/>

<!--
  You can also configure a custom breakpoint
-->
<TwicPicture
  src="art.jpg"
  alt="Art Direction Example"
  ratio="
    @lg 4/3
    @xl 21/9
  "
  focus="
    @666 bottom
    @xl top
  "
/>

Default breakpoint values can be configured here.

Image magnifier

The <TwicImg> component lets you display a lazy loaded, zoomed version of your image on mouseover.

To activate the zoom feature, set the zoom property to a number strictly greater than 1. This number represents the magnification factor of your image.

For example:

  <TwicImg src="image1.jpg" zoom="2" />
  <TwicImg src="image2.jpg" zoom="2.5" />

The zoom factor can also be configured through the --twic-zoom CSS variable.

To activate the style-driven zoom, set the zoom property to 'css' and add a new rule to your stylesheet.

For example:

  <TwicImg src="image3.jpg" zoom="css" class=".zoom-3"/>

.zoom-3 {
  --twic-zoom:3;
}

It applies only to the TwicImg component in cover mode.

Lifecycle

For TwicImg and TwicVideo components, binding state props gives access to the loading state of your image or video.

Here are the values the Component will emit :

new: when the img or video source has not started loading
loading: when the img or video source is loading
done: when the img or video source has successfully loaded
error: when an error occurred while loading the img or video source

<script>
  // component.svelte
  import TwicImg from "@twicpics/components/sveltekit/TwicImg.svelte";
  let state;

  $: {
    // Implement the logic here
    console.log( `TwicComponent emits a new state`, state );
  }
</script>


<TwicImg
  bind:state
  src="path/to/your/image"
/>

Another approach is to listen to the statechange event.

<script>
  // component.svelte
  import TwicImg from "@twicpics/components/sveltekit/TwicImg.svelte";
  let state;

  const handleStateChange = ( e ) => {
    // Implement the logic here
    state = e.detail;
    console.log( `TwicComponent emits a new state`, state );
  }
</script>


<TwicImg
  on:statechange={handleStateChange}
  src="path/to/your/image"
/>

Refit example

<TwicImg> and <TwicPicture> components allow to reframe your image on the main subject(s) they contain.

In cover mode, the resulting image will respect the ratio while maximizing the area occupied by the main subject(s).

In contain mode, the image is cropped as close as possible to the main subject(s).

To activate automatic cropping, add the refit property to your component.

By default, the subject will be placed at the center of the resulting image, but it is possible to align the subject with a given border by specifying an anchor.

Also, by default, the subject will touch the borders of the resulting image. This can be avoided by setting refit with a comma-separated length value defining padding.

For example:

  <!-- default refit: centered object(s), no padding around -->
  <TwicImg src="image1.jpg" refit />

  <!-- main subject(s) will be left aligned -->
  <TwicImg src="image3.jpg" anchor="left" refit/>

  <!-- a 5% padding will be applied around main subject(s) -->
  <TwicImg src="image2.jpg" refit="5p" />

  <!-- a 5% padding will be applied vertically, a 10% padding will be applied horizontally -->
  <TwicImg src="image3.jpg" refit="5p,10p" />

Style-Driven Approach

You can set up TwicImg and TwicVideo components using pure CSS and the power of CSS variables.

<script>
  // component.svelte
  import TwicImg from "@twicpics/components/sveltekit/TwicImg.svelte";
</script>

<style>
  .landscape {
    --twic-ratio: calc(4 / 3);
  }

  .portrait {
    --twic-ratio: calc(3 / 4);
  }

  .square {
    --twic-ratio: calc(1);
  }

  .lg {
    width: 300px;
  }

  .md {
    width: 150px;
  }

  .sm {
    width: 100px;
  }
</style>

<main>
  <div class="landscape">
    <TwicImg src="path/to/your/image"></TwicImg>
  </div>
  <div class="square">
    <TwicImg src="path/to/your/image"></TwicImg>
  </div>
  <div class="portrait">
    <TwicImg src="path/to/your/image"></TwicImg>
  </div>
  <div class="lg">
    <TwicImg src="path/to/your/image"></TwicImg>
  </div>
  <div class="md">
    <TwicImg src="path/to/your/image"></TwicImg>
  </div>
  <div class="sm">
    <TwicImg src="path/to/your/image"></TwicImg>
  </div>
</main>

Responsive Example

Setting up TwicImg and TwicVideo components using CSS and CSS variables enables hassle-free responsive designs.

Your template features a single component that will follow your CSS directives and behave responsively.

<script>
  // component.svelte
  import TwicImg from "@twicpics/components/sveltekit/TwicImg.svelte";
</script>

<style>
  .style-driven-responsive {
    --twic-ratio: calc(2 / 3);
    --twic-mode: cover;
    margin: auto;
  }

  @media (min-width: 640px) {
    .style-driven-responsive {
      --twic-ratio: calc(1);
    }
  }

  @media (min-width: 768px) {
    .style-driven-responsive {
      --twic-ratio: calc(4 / 3);
    }
  }

  @media (min-width: 1024px) {
    .style-driven-responsive {
      --twic-ratio: calc(16 / 9);
    }
  }

  @media (min-width: 1280px) {
    .style-driven-responsive {
      --twic-ratio: calc(1.85);
    }
  }

  @media (min-width: 1536px) {
    .style-driven-responsive {
      --twic-ratio: calc(21 / 9);
    }
  }
</style>

<main>
  <div class="style-driven-responsive">
    <TwicImg src="path/to/your/image"></TwicImg>
  </div>
</main>

Working with ratio="none"

With TwicPicture

It is helpful if you want to display an image with its intrinsic aspect ratio without cropping.

When using ratio="none", there is no CLS optimization, and you are responsible for it.

<!-- will display your image with it's intrinsic ratio, without any cropping -->
<TwicPicture>
  src="path/to/your/image"
  ratio="none"
</TwicPicture>

With TwicImg and TwicVideo

It is particularly useful when creating a "hero" banner. You can specify the height of your image while respecting its natural aspect ratio, and optimizing your Cumulative Layout Shift (CLS) metric.

When using ratio="none", you are responsible for properly sizing the component.

<script>
  // component.svelte
  import TwicImg from "@twicpics/components/sveltekit/TwicImg.svelte";
</script>

<style>
  /* You are responsible for properly sizing the component. */
  .hero-image {
    height:500px;
  }

  @media (min-width: 1024px) {
    .hero-image {
      height:300px;
      width:100%;
    }
  }
</style>

<TwicImg
  src="path/to/your/image"
  className="hero-image"
  ratio="none"
></TwicImg>

Components Properties

TwicImg

This component is a drop-in replacement for the img tag dedicated to content images.

It offers advanced features like optimized Cumulative Layout Shift (CLS), Low-Quality Image Placeholder (LQIP), and lazy loading out of the box.

<TwicImg
  src="<path>"
  alt="<String>"
  anchor="<String>"
  aria-*="<String>"
  bot="<String>"
  crossorigin="<anonymous|use-credentials>"
  decoding="<async|auto|sync>"
  draggable="<boolean>"
  eager="<boolean>"
  focus="<auto|coordinates>"
  id="<String>"
  intrinsic="<String>"
  mode="<contain|cover>"
  position="<css position>"
  placeholder="<preview|maincolor|meancolor|none>"
  preTransform="<String>"
  ratio="<ratio>"
  bind:state="<String>"
  on:statechange="<function>"
  referrerpolicy="<no-referrer|no-referrer-when-downgrade|origin|`origin-when-cross-origin|same-origin|strict-origin|strict-origin-when-cross-origin|unsafe-url>"
  refit="<boolean|String>"
  role="<String>"
  step="<integer>"
  style="<Object|String>"
  tabindex="<integer>"
  title="<String>"
  transition="<fade|zoom|none>"
  transitionDelay="<String>"
  transitionDuration="<String>"
  transitionTimingFunction="<String>"
  zoom="<number|String>"
/>

Attribute	Description	Type	Default
`alt`	`alt` attribute content	`String`
`anchor`	Positions the image in both `contain` and `cover` mode. Accepted values are `top`, `bottom`, `left`, `right`, `top-left`, `top-right`, `bottom-left`, `bottom-right` and `center`. `position` and `focus` take precedence in `contain` and `cover` mode respectively. Please note that `anchor` is applied after an eventual `preTransform`. When using `refit` in `cover` mode, `anchor` aligns the main object(s) with the given border side.	`String`
`aria-*`	Specifies accessibility information for assistive technologies. See ARIA Attributes page.	`String`
`bot`	A slash-separated list of TwicPics API transformations to be performed for search engine bots. This overrides all other transformations when provided, even if empty (i.e `bot=""`). See the TwicPics bot attribute documentation for more information.	`String`
`crossorigin`	Specifies the `CORS` setting for the image fetch request. See `HTML crossorigin attribute`.	`String`
`decoding`	Specifies how the browser should decode the image. See `HTML image decoding attribute`.	`String`
`draggable`	Specifies whether the image is draggable. See `global attribute draggable`.	`boolean`	`false`
`eager`	Load the image as soon as the component is mounted. This effectively means disabling lazy loading for this image.	`boolean`	`false`
`focus`	Sets the focus point in `cover` mode. `focus` takes precedence over `anchor` when both are provided. See the TwicPics focus attribute documentation for more information. Only use this attribute if you need a specific focus point or if you want to leverage smart cropping with `focus="auto"`: if you only need border-based positioning (`top`, `bottom`, `left`, `right`, etc), use `anchor` instead.	`String`
`id`	Specifies a unique `id` for the image. See `global attribute id`.	`String`
`intrinsic`	Dimensions in pixels of the original image, formatted `<width>x<height>` (eg. 1920x1080). It prevents image upscaling and limits the number of generated variants. If using `preTransform`, you should specify the intrinsic dimensions of the resulting image. Using incorrect values can lead to display issues, see the intrinsic attribute documentation.	`String`
`mode`	Can be `contain` or `cover` and determines if the image fills the area and is cropped accordingly (`cover`) or if the image will sit inside the area with no cropping (`contain`).	`String`	`cover`
`placeholder`	Can be `preview`, `meancolor`, `maincolor` or `none`. See the TwicPics output transformation documentation for more information. Setting will be overridden to `none` when using `zoom` `transition`.	`String`	`preview`
`position`	Positions the image in `contain` mode. `position` takes precedence over `anchor` when both are provided. Syntax is the same as for CSS position properties `background-position` and `object-position`. Only use this attribute if you need precise positionning: if you only need border-based positionning (`top`, `bottom`, `left`, `right`, etc), use `anchor` instead.	`String`	`center`
`preTransform`	A slash-separated list of TwicPics API transformations to be performed before resizing the image (see the TwicPics Manipulation documentation). Note that `anchor` and `focus` are applied after `preTransform`: if you need to specify a specific focus point for your `preTransform` then it needs to be part of the expression (like `preTransform="focus=auto/crop=50px50p"` for instance). Be aware that using this option can lead to unexpected results so use with caution!	`String`
`ratio`	A unitless `width/height` or `width:height` value pair (as in `4/3` or `4:3`) that defines the aspect ratio of the display area. If `height` is not specified, it is assumed to be `1`. A square area will be created by default. When set to `none`, ratio is determined based on width and height as computed by the browser following your `CSS` definitions. The `--twic-ratio` CSS variable is ignored in this instance. You are responsible for properly sizing the component when `ratio="none"`.	`String or number`	`1`
`referrerpolicy`	Specifies the referrer to use when fetching the image. See the `HTML image referrerpolicy attribute`.	`String`
`refit`	Reframes the image to maximize the area occupied by the main object(s) while respecting `ratio` in `cover` mode. Crops the image as close as possible to the main object(s) in `contain` mode. Can be `true`, `false` or a list of comma-separated length defining padding. See the TwicPics refit documentation for more information.	`boolean or String`	`false`
`role`	Specifies the ARIA role of the container.	`String`	`img`
`src`	Path to the image. When not provided, a red lightweight `svg` placeholder that displays its intrinsic dimensions is displayed in place of the absent image. When env is set to `offline`, that red lightweight `svg` is replaced by a simple red placeholder.	`String`
`state`	A string property being update each time the asset loading state is updated. Values can be `new`, `loading`, `done` or `error`.	`String`
`statechange`	A custom event dispatched each time the image loading state is updated. Emitted values can be `new`, `loading`, `done` or `error`.	`( e: CustomEvent ) => void`
`step`	See the TwicPics step attribute documentation for more information.	`Integer`	`10`
`style`	Defines inline `CSS` styles for the image. See `global attribute style`.	`Object or String`
`title`	`title` representing information related to the image. See `global attribute title`.	`String`
`tabindex`	Specifies the tab order of the image. See `global attribute tabindex`.	`Integer`
`transition`	Determines how the image will be revealed once loaded. With a fade in effect (`fade`), a zoom effect (`zoom`) or without any transition (`none`). Unsupported values are handled as `fade`.	`String`	`fade`
`transitionDuration`	Duration of the transition effect.	`String`	`400ms`
`transitionTimingFunction`	CSS timing function applied to the transition effect.	`String`	`ease`
`transitionDelay`	Transition delay of the transition effect.	`String`	`0ms`
`zoom`	Enables zoom feature and sets the magnification factor. Must be a number strictly greater than 1 as in `"1.5"` or `1.5`. When set to `'css'`, magnification factor is defined through the CSS variable `--twic-zoom`.Should only be applied to images in cover `mode`. See Image magnifier.	`String	number`

TwicPicture

This component serves as a seamless replacement for the picture element.

With a primary focus on maximizing the Largest Contentful Paint (LCP) score with optimized Cumulative Layout Shift (CLS), it effortlessly generates the srcset and source attributes for resolution switching and art direction, all derived from a single master file transformed through the TwicPics API.

<TwicPicture
  src="<path>"
  aria-*="<String>"
  alt="<String>"
  anchor="<String>"
  crossorigin="<anonymous|use-credentials>"
  decoding="<async|auto|none|sync>"
  draggable="<boolean>"
  eager="<boolean>"
  fetchpriority="<high|low|auto>"
  focus="<auto|coordinates>"
  id="<String>"
  mode="<contain|cover>"
  position="<String>"
  preTransform="<String>"
  ratio="<ratio>"
  referrerpolicy="<no-referrer|no-referrer-when-downgrade|origin|`origin-when-cross-origin|same-origin|strict-origin|strict-origin-when-cross-origin|unsafe-url>"
  refit="<boolean|String>"
  role="<String>"
  sizes="<String>"
  style="<Object|String>"
  tabindex="<integer>"
  title="<String>"
/>

Attribute	Description	Type	Default
`alt`	`alt` attribute content	`String`
`anchor`	Positions the image in both `contain` and `cover` mode. Accepted values are `top`, `bottom`, `left`, `right`, `top-left`, `top-right`, `bottom-left`, `bottom-right` and `center`. `position` and `focus` take precedence in `contain` and `cover` mode respectively. Please note that `anchor` is applied after an eventual `preTransform`. Can be set at different breakpoints.	`String`
`aria-*`	Specifies accessibility information for assistive technologies. See ARIA Attributes page.	`String`
`crossorigin`	Specifies the `CORS` setting for the image fetch request. See `HTML crossorigin attribute`.	`String`
`decoding`	Specifies how the browser should decode the image. See `HTML image decoding attribute`.	`String`
`draggable`	Specifies whether the image is draggable. See `global attribute draggable`.	`boolean`	`false`
`eager`	Load the image as soon as the `picture` element is processed and set `fetchpriority` to `high`. This effectively means disabling lazy loading for this image. Recommended for optimal Largest Contentful Paint (LCP) display.	`boolean`	`false`
`fetchpriority`	Acts as standard fetchpriority property. Can be `high`, `low`or `auto`. Defaults to `high` when `eager` is true.	`string`
`focus`	Sets the focus point in `cover` mode. `focus` takes precedence over `anchor` when both are provided. See the TwicPics focus attribute documentation for more information. Only use this attribute if you need a specific focus point or if you want to leverage smart cropping with `focus="auto"`: if you only need border-based positionning (`top`, `bottom`, `left`, `right`, etc), use `anchor` instead. Can be set at different breakpoints.	`String`
`id`	Specifies a unique `id` for the image. See `global attribute id`.	`String`
`mode`	Can be `contain` or `cover` and determines if the image fills the area and is cropped accordingly (`cover`) or if the image will sit inside the area with no cropping (`contain`). Can be set at different breakpoints.	`String`	`cover`
`position`	Positions the image in `contain` mode. `position` takes precedence over `anchor` when both are provided. Accepted values are `top`, `bottom`, `left`, `right`, `top-left`, `top-right`, `bottom-left`, `bottom-right` and `center`. Can be set at different breakpoints.	`String`	`center`
`preTransform`	A slash-separated list of TwicPics API transformations to be performed before resizing the image (see the TwicPics Manipulation documentation). Note that `anchor` and `focus` are applied after `preTransform`: if you need to specify a specific focus point for your `preTransform` then it needs to be part of the expression (like `preTransform="focus=auto/crop=50px50p"` for instance). Be aware that using this option can lead to unexpected results so use with caution! Can be set at different breakpoints.	`String`
`ratio`	A unitless `width/height` or `width:height` value pair (as in `4/3` or `4:3`) that defines the aspect ratio of the display area. If `height` is not specified, it is assumed to be `1`. A square area will be created by default. When set to `none`, the image is displayed with its intrinsic aspect ratio. In this case, you are responsible for optimizing the Cumulative Layout Shift (CLS). Can be set at different breakpoints.	`String or number`	`1`
`referrerpolicy`	Specifies the referrer to use when fetching the image. See the `HTML image referrerpolicy attribute`.	`String`
`refit`	Reframes the image to maximize the area occupied by the main object(s) while respecting `ratio` in `cover` mode. Crops the image as close as possible to the main object(s) in `contain` mode. Can be `true`, `false` or a list of comma-separated length defining padding. See the TwicPics refit documentation for more information.	`boolean or String`	`false`
`role`	Specifies the ARIA role of the container.	`String`	`img`
`sizes`	Specifies the layout width of the image for each breakpoints using media query syntax. The value of this parameter has a significant impact on performance. Ensure to configure it carefully. See sizes.	`String`
`src`	Path to the image.	`String`
`style`	Defines inline `CSS` styles for the image. See `global attribute style`.	`Object or String`
`title`	`title` representing information related to the image. See `global attribute title`.	`String`
`tabindex`	Specifies the tab order of the image. See `global attribute tabindex`.	`Integer`

TwicVideo

This component is a drop-in replacement for video.

It provides seamless playback for videos optimized with TwicPics, offering advanced features like optimized Cumulative Layout Shift (CLS), Low-Quality Image Placeholder (LQIP), and lazy loading out of the box.

<TwicVideo
  src="<path>"
  anchor="<String>"
  aria-*="<String>"
  bot="<String>"
  crossorigin="<anonymous|use-credentials>"
  draggable="<boolean>"
  duration="<String|number>"
  eager="<boolean>"
  from="<String|number>"
  focus="<auto|coordinates>"
  id="<String>"
  intrinsic="<String>"
  mode="<contain|cover>"
  position="<css position>"
  posterFrom="<String|number>"
  placeholder="<preview|maincolor|meancolor|none>"
  preTransform="<String>"
  ratio="<ratio>"
  bind:state="<String>"
  on:statechange="<function>"
  role="<String>"
  step="<integer>"
  style="<Object|String>"
  tabindex="<integer>"
  title="<String>"
  to="<String|number>"
  transition="<fade|zoom|none>"
  transitionDelay="<String>"
  transitionDuration="<String>"
  transitionTimingFunction="<String>"
/>

Attribute	Description	Type	Default
`anchor`	Positions the video in both `contain` and `cover` mode. Accepted values are `top`, `bottom`, `left`, `right`, `top-left`, `top-right`, `bottom-left`, `bottom-right` and `center`. `position` and `focus` take precedence in `contain` and `cover` mode respectively. Please note that `anchor` is applied after an eventual `preTransform`. When using `refit` in `cover` mode, `anchor` aligns the main object(s) with the given border side.	`String`
`aria-*`	Specifies accessibility information for assistive technologies. See ARIA Attributes page.	`String`
`bot`	A slash-separated list of TwicPics API transformations to be performed for search engine bots. This overrides all other transformations when provided, even if empty (i.e `bot=""`). See the TwicPics bot attribute documentation for more information.	`String`
`crossorigin`	Specifies the `CORS` setting for the video fetch request. See `HTML crossorigin attribute`.	`String`
`draggable`	Specifies whether the video is draggable. See `global attribute draggable`.	`boolean`	`false`
`duration`	Limits the duration of the video. `duration` is expressed in seconds and must be a positive number. `duration` will not move the starting point of the video: to do so, you'll have to use the `from` property. See duration documentation.	`String or number`
`eager`	Load the video as soon as the component is mounted. This effectively means disabling lazy loading for this video.	`boolean`	`false`
`focus`	Sets the focus point in `cover` mode. `focus` takes precedence over `anchor` when both are provided. See the TwicPics focus attribute documentation for more information. Only use this attribute if you need a specific focus point or if you want to leverage smart cropping with `focus="auto"`: if you only need border-based positioning (`top`, `bottom`, `left`, `right`, etc), use `anchor` instead.	`String`
`from`	Moves the starting point of the video. `from` is expressed in seconds and must be a positive number. `from` will not move the end point of the video: to do so, you'll have to use the `duration` or `to` properties. See from documentation. See from documentation.	`String or number`
`id`	Specifies a unique `id` for the video. See `global attribute id`.	`String`
`intrinsic`	Dimensions in pixels of the original video, formatted `<width>x<height>` (eg. 1920x1080). It prevents video upscaling and limits the number of generated variants. If using `preTransform`, you should specify the intrinsic dimensions of the resulting video. Using incorrect values can lead to display issues, see the intrinsic attribute documentation.	`String`
`mode`	Can be `contain` or `cover` and determines if the video fills the area and is cropped accordingly (`cover`) or if the video will sit inside the area with no cropping (`contain`).	`String`	`cover`
`placeholder`	Can be `preview`, `meancolor`, `maincolor` or `none`. See the TwicPics output transformation documentation for more information. Setting will be overridden to `none` when using `zoom` `transition`.	`String`	`preview`
`position`	Positions the video in `contain` mode. `position` takes precedence over `anchor` when both are provided. Syntax is the same as for CSS position properties `background-position` and `object-position`. Only use this attribute if you need precise positionning: if you only need border-based positionning (`top`, `bottom`, `left`, `right`, etc), use `anchor` instead.	`String`	`center`
`posterFrom`	Determines which frame of the source video should be used as a poster / preview. `posterFrom` is expressed in seconds and must be a positive number. By default `posterFrom` is equal to 0, meaning the very first frame of the video is used. `posterFrom` will not modify the video in any way: to do so, you'll have to use the `duration`, `from` or `to` properties.	`String or number`
`preTransform`	A slash-separated list of TwicPics API transformations to be performed before resizing the video (see the TwicPics Manipulation documentation). Note that `anchor` and `focus` are applied after `preTransform`: if you need to specify a specific focus point for your `preTransform` then it needs to be part of the expression (like `preTransform="focus=auto/crop=50px50p"` for instance). Be aware that using this option can lead to unexpected results so use with caution!	`String`
`ratio`	A unitless `width/height` or `width:height` value pair (as in `4/3` or `4:3`) that defines the aspect ratio of the display area. If `height` is not specified, it is assumed to be `1`. A square area will be created by default. When set to `none`, ratio is determined based on width and height as computed by the browser following your `CSS` definitions. The `--twic-ratio` CSS variable is ignored in this instance. You are responsible for properly sizing the component when `ratio="none"`.	`String or number`	`1`
`role`	Specifies the ARIA role of the container.	`String`
`src`	Path to the video. When not provided, a red lightweight `svg` placeholder that displays its intrinsic dimensions is displayed in place of the absent video. When env is set to `offline`, that red lightweight `svg` is replaced by a simple red placeholder.	`String`
`state`	A string property being update each time the asset loading state is updated. Values can be `new`, `loading`, `done` or `error`.	`String`
`statechange`	A custom event dispatched each time the image loading state is updated. Emitted values can be `new`, `loading`, `done` or `error`.	`( e: CustomEvent ) => void`
`step`	See the TwicPics step attribute documentation for more information.	`Integer`	`10`
`style`	Defines inline `CSS` styles for the video. See `global attribute style`.	`Object or String`
`title`	`title` representing information related to the video. See `global attribute title`.	`String`
`to`	Moves the end point of the video. `to` is expressed in seconds and must be a positive number. `to` will not move the starting point of the video: to do so, you'll have to use the `from` property. See to documentation.	`String or number`
`tabindex`	Specifies the tab order of the video. See `global attribute tabindex`.	`Integer`
`transition`	Determines how the video will be revealed once loaded. With a fade in effect (`fade`), a zoom effect (`zoom`) or without any transition (`none`). Unsupported values are handled as `fade`.	`String`	`fade`
`transitionDuration`	Duration of the transition effect.	`String`	`400ms`
`transitionTimingFunction`	CSS timing function applied to the transition effect.	`String`	`ease`
`transitionDelay`	Transition delay of the transition effect.	`String`	`0ms`

CSS Variables

List of variables that can be used to configure your components using pure CSS:

<selector> {
  --twic-ratio: <ratio>;
  --twic-mode: <contain|cover>;
  --twic-position: <css position>;
  --twic-transition-delay: <string>;
  --twic-transition-duration: <string>;
  --twic-transition-timing-function:<string>;
  --twic-zoom:<number>;
}

Each CSS variable corresponds to one of the components attributes listed in the Components Properties section. If present, the attribute takes precedence over the corresponding CSS variable.

Variable	Description	HTML Attribute	Default
`--twic-mode`	Can be `contain` or `cover` and determines if the image fills the area and is cropped accordingly (`cover`) or if the image will sit inside the area with no cropping (`contain`).	`mode`	`cover`
`--twic-position`	Only useful in `contain` mode. Locates the image inside the area. Syntax is the same as for CSS position properties like background-position or object-position. Useful values are `top`, `bottom`, `left`, `right`, `left top`, `left bottom` and so on.	`position`	`center`
`--twic-ratio`	Floating point value corresponding to a unitless `width/height` ratio (as in `calc(4/3)` or `1.333`). Ratio will correspond to a square area by default.	`ratio`	`1`
`--twic-transition-delay`	Transition delay of the transition effect.	`transitionDelay`	`0ms`
`--twic-transition-duration`	Duration of the transition effect.	`transitionDuration`	`400ms`
`--twic-transition-timing-function`	CSS timing function applied to the transition effect.	`transitionTimingFunction`	`ease`
`--twic-zoom`	Strictly greater than 1 floating point value corresponding to the zoom factor to be applied. Only applies to `TwicImg` with `zoom` property set to `"CSS"`.	`number`

Default Breakpoints

There are six default breakpoints, each corresponding to common device resolutions:

Breakpoint	Size (pixels)
`xs`	320
`sm`	640
`md`	768
`lg`	1024
`xl`	1280
`2xl`	1536

These values are customizable during component configuration. Refer to Setup Options.

Examples

You can find usage examples in our online demo project.

Questions and feedback

Feel free to submit an issue or ask us anything by emailing support@twic.pics.

Other frameworks

TwicPics provides the most versatile solution on the market for delivering responsive media.

TwicPics Components are available in the most popular Javascript frameworks.

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svelteKit.md

svelteKit.md

Overview

What is TwicPics?

What is TwicPics Components?

Display a Critical Image

Display a Content Image

Display a Video

Installation

Setup

Setting up TwicPics Components in your `SvelteKit` project

src/routes/+layout.svelte

Setup Options

Usage

Basic usage

Bulk loading with TwicView

Critical Images

Resolution switching

Art Direction

Image magnifier

Lifecycle

Refit example

Style-Driven Approach

Responsive Example

Working with ratio="none"

With TwicPicture

With TwicImg and TwicVideo

Components Properties

TwicImg

TwicPicture

TwicVideo

CSS Variables

Default Breakpoints

Examples

Questions and feedback

Other frameworks

License

Files

svelteKit.md

Latest commit

History

svelteKit.md

File metadata and controls

Overview

What is TwicPics?

What is TwicPics Components?

Display a Critical Image

Display a Content Image

Display a Video

Installation

Setup

Setting up TwicPics Components in your SvelteKit project

src/routes/+layout.svelte

Setup Options

Usage

Basic usage

Bulk loading with TwicView

Critical Images

Resolution switching

Art Direction

Image magnifier

Lifecycle

Refit example

Style-Driven Approach

Responsive Example

Working with ratio="none"

With TwicPicture

With TwicImg and TwicVideo

Components Properties

TwicImg

TwicPicture

TwicVideo

CSS Variables

Default Breakpoints

Examples

Questions and feedback

Other frameworks

License

Setting up TwicPics Components in your `SvelteKit` project