Most of the information systems using user authentication also work with some kind of avatars - images enabling other users to see who commented, posted or made anything else in the system. When we want to be able to show user avatars, we need to enable users to upload their avatar or generate some default.
In this article I am going to show you how to:
- generate user avatar by their unique ID using
jdenticon - select avatar from file
- crop selected avatar using
cropper.jsandreact-cropperlibraries
Generating default avatar
When the user hasn't selected their own avatar, we have few options what to show instead of it. We can show nothing, use some placeholder image 👤 or generate some pretty cool image. 😎
There are multiple avatar generators in npm. I chose jdenticon because I like the images it produces.
You can also find this nice icon designer in their docs, so you can customize the output. But I am going to stick with defaults.
So let's see how to use the library to generate the image.
import { ComponentProps, FC, useState } from 'react';
export const AutoAvatar: FC<
ComponentProps<'img'> & { userId: number; size: number }
> = ({ userId, size, ...imgProps }) => {
const [base64, setBase64] = useState(undefined as string | undefined);
// using dynamic import to save some loading
import('jdenticon').then(({ toSvg }) => {
const svgString = toSvg(userId, size);
const base64 = Buffer.from(svgString).toString('base64');
setBase64(base64);
});
return base64 ? (
<div style={{ backgroundColor: 'rgb(225,225,225)', display: 'flex' }}>
<img
{...imgProps}
src={`data:image/svg+xml;base64,${base64}`}
alt={'User Avatar'}
/>
</div>
) : (
<div style={{ width: size, height: size, display: 'inline-block' }}>
Loading...
</div>
);
};
What I am doing here is loading the jdenticon library using dynamic import. The library has approx. 45 kb, so it is good idea to let webpack download it dynamically just when it's needed.
When it's loaded, I let the library produce svg by user ID. The library works similarly as good hash function so for near values it produces completely different results.
If you don't trust me, you can play with that here.
When it's generated I am converting the result to base64 to use it in img src attribute.
That's it. Avatar generated! 🥳
Letting user select an avatar
To let user select an avatar, we can simply use input element with file type attribute.
<input
type="file"
accept="image/png,image/jpeg,image/gif"
/>
But this input is pretty ugly. So I am going to hide it and provide my own cool button instead of this. Then I can trigger
click on this input to open the system file selection dialog.
import React, {createRef} from "react";
export const ImageSelect = () => {
const fileRef = createRef<HTMLInputElement>();
const onFileInputChange: React.ChangeEventHandler<HTMLInputElement> = (e) => {
console.log(e.target?.files?.[0]);
}
return (
<>
<input
type="file"
style={{display: 'none'}}
ref={fileRef}
onChange={onFileInputChange}
accept="image/png,image/jpeg,image/gif"
/>
<button
onClick={() => fileRef.current?.click()}
>Cool Button
</button>
</>
)
}
Like this, we can use any event to open the file selection. When the user selects some file, it is printed to the console. Now we would be prepared to upload the file to backend. But that would be lame. Let's also crop the image! 🎈
Cropping the image
To provide a bit more comfort to our users it would be nice to enable them to crop the image before they actually upload it. This can be done using cropper.js and its React wrapper react-cropper.
import React, {createRef} from "react";
import {Cropper, ReactCropperElement} from "react-cropper";
import 'cropperjs/dist/cropper.css';
export const ImageCrop = () => {
const cropperRef = createRef<ReactCropperElement>();
return (
<Cropper
src="<the iamge src>"
style={{height: 400, width: 400}}
autoCropArea={1}
aspectRatio={1}
viewMode={3}
guides={false}
ref={cropperRef}
/>
)
}
What does the configuration do?
- autoCropArea=1 - selects whole image by default
- aspectRatio=1 - makes it 1:1, so it is square
- viewMode=3 - makes the image to cover cropper size and disables selecting empty areas by moving out from canvas
- guides=false - removes tiny lines, which I found unnecessary for croping avatars
So now it would be nice to get the actual cropped image. We can do it this way:
import React, {createRef, useState} from "react";
import {Cropper, ReactCropperElement} from "react-cropper";
import 'cropperjs/dist/cropper.css';
export const ImageCrop = () => {
const cropperRef = createRef<ReactCropperElement>();
const [cropped, setCropped] = useState(null as string | null);
const onSaveClick = () => {
const imageElement: any = cropperRef?.current;
const cropper: any = imageElement?.cropper;
setCropped(cropper.getCroppedCanvas().toDataURL())
}
return (
<>
<Cropper
src={"https://picsum.photos/500/300"}
style={{height: 400, width: 400}}
autoCropArea={1}
aspectRatio={1}
viewMode={3}
guides={false}
ref={cropperRef}
/>
<button onClick={onSaveClick}>Crop</button>
{cropped &&
<img src={cropped} alt={"It's cropped"}/>
}
</>
)
}
If we would like to get the image for uploading, it would be better to use
cropper.getCroppedCanvas().toBlog()
Which provides a blob which we can use to create a file to upload.
Depends, for what we like to use the result. If we would like to upload it, blob is what we are looking for. To just show the image dataUrl is our choice.
Cool! So now we can also crop the image. Now, let's combine it all together!
import React, {createRef, useState} from 'react';
import './App.css';
import {Cropper, ReactCropperElement} from "react-cropper";
import 'cropperjs/dist/cropper.css';
import './roundedCropper.css';
// this transforms file to base64
const file2Base64 = (file: File): Promise<string> => {
return new Promise<string>((resolve, reject) => {
const reader = new FileReader();
reader.readAsDataURL(file);
reader.onload = () => resolve(reader.result?.toString() || '');
reader.onerror = (error) => reject(error);
});
};
const App = () => {
// ref of the file input
const fileRef = createRef<HTMLInputElement>();
// the selected image
const [uploaded, setUploaded] = useState(null as string | null);
// the resulting cropped image
const [cropped, setCropped] = useState(null as string | null);
// the reference of cropper element
const cropperRef = createRef<ReactCropperElement>();
const onFileInputChange: React.ChangeEventHandler<HTMLInputElement> = (e) => {
const file = e.target?.files?.[0];
if (file) {
file2Base64(file).then((base64) => {
setUploaded(base64);
});
}
}
const onCrop = () => {
const imageElement: any = cropperRef?.current;
const cropper: any = imageElement?.cropper;
setCropped(cropper.getCroppedCanvas().toDataURL())
}
return (
<>
<div className="App">
{
uploaded ?
<div>
<Cropper
src={uploaded}
style={{height: 400, width: 400}}
autoCropArea={1}
aspectRatio={1}
viewMode={3}
guides={false}
ref={cropperRef}
/>
<button onClick={onCrop}>Crop</button>
{cropped && <img src={cropped} alt="Cropped!"/>}
</div>
:
<>
<input
type="file"
style={{display: 'none'}}
ref={fileRef}
onChange={onFileInputChange}
accept="image/png,image/jpeg,image/gif"
/>
<button
onClick={() => fileRef.current?.click()}
>Upload something!
</button>
</>}
</div>
</>
);
}
export default App;
When user selects an image, the cropper component is rendered. When user hits the crop button, the resulting cropped image is shown. That's all. Easy-peasy.
Making the selection rounded
If you would like to use the avatars rounded, you would probably like to make also the selection rounded.
To do so, we have to style the cropper elements.
.cropper-crop-box, .cropper-view-box {
border-radius: 50%;
}
TL;DR
In this article I explained how to generate default avatar using jdenticon library and how to select an image file and also, how to enable user to crop it using react-croper library.
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