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Thumbnail generator

@uppy/thumbnail-generator generates proportional thumbnails (file previews) for images that are added to Uppy.

When should I use this?​

This plugin is included by default with the Dashboard plugin, and can also be useful to display image previews in a custom UI.

note

Thumbnails are only generated for local files. Remote files through Companion generally won’t have thumbnails because they are downloaded on the server. Some providers, such as Google Drive, have baked in thumbnails into their API responses.

Install​

npm install @uppy/thumbnail-generator

Use​

If you use the Dashboard then it’s already installed. If you want to use it programmatically for your own UI:

import Uppy from '@uppy/core';
import ThumbnailGenerator from '@uppy/thumbnail-generator';

const uppy = new Uppy();

uppy.use(ThumbnailGenerator);
uppy.on('thumbnail:generated', (file, preview) => doSomething(file, preview));

API​

Options​

id​

A unique identifier for this plugin (string, default: 'ThumbnailGenerator').

locale​

export default {
	strings: {
		generatingThumbnails: 'Generating thumbnails...',
	},
};

thumbnailWidth​

Width of the resulting thumbnail (number, default: 200).

Thumbnails are always proportional and not cropped. If width is provided, height is calculated automatically to match ratio. If both width and height are given, only width is taken into account.

thumbnailHeight​

Height of the resulting thumbnail (number, default: 200).

Thumbnails are always proportional and not cropped. If height is provided, width is calculated automatically to match ratio. If both width and height are given, only width is taken into account.

note

Produce a 300px height thumbnail with calculated width to match ratio:

uppy.use(ThumbnailGenerator, { thumbnailHeight: 300 });

Produce a 300px width thumbnail with calculated height to match ratio (and ignore the given height):

uppy.use(ThumbnailGenerator, { thumbnailWidth: 300, thumbnailHeight: 300 });

See issue #979 and #1096 for details on this feature.

thumbnailType​

MIME type of the resulting thumbnail (string, default: 'image/jpeg').

This is useful if you want to support transparency in your thumbnails by switching to image/png.

waitForThumbnailsBeforeUpload​

Whether to wait for all thumbnails to be ready before starting the upload (boolean, default: false).

If set to true, Thumbnail Generator will invoke Uppy’s internal processing stage and wait for thumbnail:all-generated event, before proceeding to the uploading stage. This is useful because Thumbnail Generator also adds EXIF data to images, and if we wait until it’s done processing, this data will be available on the server after the upload.

Events​

info

You can use on and once to listen to these events.

thumbnail:generated​

Emitted with file and preview local url as arguments:

uppy.on('thumbnail:generated', (file, preview) => {
	const img = document.createElement('img');
	img.src = preview;
	img.width = 100;
	document.body.appendChild(img);
});