README.md

Vue Responsive Image

Vue Responsive Image is a Vue component that allows you to quickly insert responsive image tags in your Vue project, provided you have some automated system that produces the various sizes of images required. The component calculates all source sizes and, depending on the parameters passed, generates the appropriate <img> tag and its srcset attribute and, if needed, separate <source> tags for tablet portrait and smartphone views.

Requirements

You need to have some system that automatically generates the images for you when an URL with the appropriate format is called, for example: http://via.placeholder.com/1920x1080

The master branch contains the version 2.0 that works with Vue 3. The version compatible with Vue 2 is in the branch 1.0.

Standard Installation

npm

npm install --save-dev vue-responsive-image

Vue

Import the component in the *.vue template that uses it

import VueResponsiveImage from 'vue-responsive-image'

Fast installation

Just copy the ResponsiveImage.vue component somewhere in your project and import it in the templates that need it. Remember that this way your component won't be automatically upgraded with bugfixes and improvements, though!

Using a .js file

You can also include the script you find in the dist/ folder called vue-responsive-image-web.min.js. This way you can use it directly in simple Vue-based pages. To find out how to include it, check the HTML file in web-test/web-test.html. Keep in mind that in this case your component won't be automatically upgraded unless you manually update the script.

Usage

VueResponsiveImage must be used as a component in your template.

Minimal usage:

<vue-responsive-image
    :image-url="'http://via.placeholder.com/%width%x%height%'"
    :image-ratio="16/9"
  ></vue-responsive-image>

Complete set of options:

<vue-responsive-image
    :image-url="'http://via.placeholder.com/%width%x%height%'"
    :error-image-url="'https://via.placeholder.com/160x90.png/09f/fff?text=Not+Found'"
    :show-error-image="true"
    :width-on-screen="50"
    :width-on-screen-tablet="75"
    :width-on-screen-smartphone="100"
    :image-ratio="16/9"
    :alt="'test1'"
    :image-class="'vw50'"
    :mode="'all'"
    :lazy-loading="false"
  ></vue-responsive-image>

Parameters

It currently supports the following parameters:

Parameter	Default value
image-url	N/a	The base url to create images, with a width and height placeholder which will be replaced by the component. Example:http://via.placeholder.com/%width%x%height%. %width% and %height% will be replaced with the calculated width and height for each image.
show-error-image	false	Whether to show the error image instead of the broken image if the current image fails to load
error-image-url	N/a	The URL for an image to show in case of failure to load the image. It can be an inline SVG. The component now detects image load failures and instead of showing broken images shows an error image. The default is a grey-background svg
width-on-screen	100	The percentage of the screen the image will occupy in the layout. Used to determine the various s0izes for the srcset of the image
width-on-screen-tablet	-	The percentage of the screen the image will occupy in the layout on tablet-portrait mode, only if different from default
width-on-screen-smartphone	-	The percentage of the screen the image will occupy in the layout on smartphone mode, only if different from default
image-ratio	16/9	The width to height ratio of the image, used to determine the height of the final images
alt	''	The alt attribute for the image
class	''	The extra class(es) to be added to the image. The class "vue-reponsive-image" is added by default
mode	'all'	Possible values: 'all', 'tablet', 'smartphone', 'mobile'. The desidered mode of operation for the main image, if only "mobile" is passed, then desktop sizes will not be generated, etc.
lazy-loading	false	Boolean - whether to enable the default HTML lazy loading mechanism, with attribute loading="lazy" set on the image if this attribute is set to true

Demo

You can find a simple demo here: https://codepen.io/paolomioni/pen/PeNoQg

Principles

This plugin is based on the analyses I made for my clients, and explained in an article I wrote which you can find here:

Applying srcset: choosing the right sizes for responsive images at different breakpoints

Assumptions

This plugin assumes that you are using the same image, with the same proportions (the same width and height ratio), for all breakpoints. It might support different ratio images in the future.

It also assumes that you will use the same image width for desktop and tablet landscape, but that you might need a different overall image width for tablet portrait and smartphone.

For example, your image might occupy 33% of the screen on desktop, 50% on tablet portrait, and 100% on smartphones. This requires completely different sizes for the final images in the HTML, and the plugin calculates those for you. This is by far the most common use case according to my experience.

Testing

There is a unit test suite made with:

• mocha-webpack for the version 1.0
• jest for the version 2.0

Just clone the project, install with npm, and run:

• npm run test for the version 1.0
• npm run test:unit for the version 2.0

Roadmap

• More sophisticated options for different breakpoints and different ratios
• Automatic lazy loading using the Intersection Observer API
• Integration with some routine to produce the images with server-side tools according to the plugin's logic
• A more thorough unit test suite
• Switch to a single config parameter? Not sure if it's needed

Feel free to contact me with proposal, requests, and pull requests. Bugs and issues should be submitted on the GitHub page of the project.

ChangeLog

• 1.1.0 - add lazy loading option

Credits

Created by Paolo Mioni for HCE Web Agency. https://www.hce.it/

License

MIT