react-smartpicture

Crop images with a focuspoint for reactJs.

Features

• Automatically resizes and centers an images to fit in a container
• Uses coordinates to ensure a part of an image is always shown (like a face)
• Reacts on src changes and changes in size of the container (not screen resizes)
• Offers callback when images is loaded and resized
• Works with picture element for media optimized sources
• No jQuery required

How it works

SmartPicture creates a container div and puts an image or picture (depending on sources are used) inside it.

The prop "containerClassName" specifies the className of the container div where the dimensions should be written.

Examples

The examples use an image-container css class which might look like:

.image-container {
    width: 300px;
    height: 100px; 
}

Basic Example

import SmartPicture from 'react-smartpicture';

...

<SmartPicture
    src="/path/to/my/image.jpg"
    containerClassName="image-container"
    alt="my image"
    focus={{x: 0.8, y: 0.3}} />

Full example with callback

import SmartPicture from 'react-smartpicture';

constructor(props) {
    super(props);
    
    ...
    
    this.sources = [
        {   
            media: "min-width: 640px",
            srcSet: "/myimage-large.jpg 1x, /[email protected] 2x"
        },
        {   
            media: "min-width: 320px",
            srcSet: "/myimage-small.jpg 1x, /[email protected] 2x"
        }
    ];
}
 
 ...
 
 function onResize(el) {
    console.log("image is ready", el);
 }
 
 ...
 
 <SmartPicture
         src="/path/to/my/image.jpg"
         sources={this.sources}
         containerClassName="image-container"
         alt="my image"
         id="myImageContainer"
         pivotToCenter={true}
         position="absolute"
         onResize={this.onResize.bind(this)}
         focus={{x: 0.5, y: -0.5}} />

Properties

Property	Type	Description
src	string, required	source of the image, used as <img src="" />, for picture elements this is the default fallback src
alt	string, recommended	alt text of the image
id	string	adds the attribute id to the container div
focus	Object with x and y	By default, x=0 is on the left border of the image, 1 on the right and 0.5 in the center - y=0 is on the top and 1 is on the bottom. If focus is not set it defaults to the center of the image
pivotToCenter	boolean, default: false	converts the coordinates, that x:0, y:0 is in the center of the image, x:-1, y:1 is on left-top and x:1, y:-1 right-bottom
sources	array	sets the sources used for optimized media handling, see this.sources in full example
position	string	By default, the container div is set to "position: relative" by inline css. In some cases it may be useful to set it f.e. to "absolute". Also "relative" seems to have an issue with full-screen images (height: 100vh) as it renders the image 1px too short in height. Setting position to "absolute" fixes this.
onResize	function	used as callback when image is ready (loaded and resized). As the image "jumps" after loading to get resized and centered, this is useful for overlays / hiding the image until it's ready