Resize and crop images in the Browser with orientation fix using exif

ImageTools.js

import EXIF from 'exif-js';

const hasBlobConstructor = typeof (Blob) !== 'undefined' && (function checkBlobConstructor() {
    try {
        return Boolean(new Blob());
    } catch (error) {
        return false;
    }
}());

const hasArrayBufferViewSupport = hasBlobConstructor && typeof (Uint8Array) !== 'undefined' && (function checkArrayBufferView() {
    try {
        return new Blob([new Uint8Array(100)]).size === 100;
    } catch (error) {
        return false;
    }
}());

const hasToBlobSupport = (typeof HTMLCanvasElement !== 'undefined' ? HTMLCanvasElement.prototype.toBlob : false);

const hasBlobSupport = (hasToBlobSupport || (typeof Uint8Array !== 'undefined' && typeof ArrayBuffer !== 'undefined' && typeof atob !== 'undefined'));

const hasReaderSupport = (typeof FileReader !== 'undefined' || typeof URL !== 'undefined');

const hasCanvasSupport = (typeof HTMLCanvasElement !== 'undefined');

export default class ImageTools {

    constructor() {
        this.browserSupport = this.isSupportedByBrowser();
    }

    isSupportedByBrowser = () => (hasCanvasSupport && hasBlobSupport && hasReaderSupport);

    resize = (file, maxDimensions) => new Promise((resolve) => {

        if (!this.browserSupport || !file.type.match(/image.*/)) return resolve(file);  // early exit - not supported

        if (file.type.match(/image\/gif/)) return resolve(file); // early exit - could be an animated gif

        const image = document.createElement('img');

        image.onload = () => {
            let width  = image.width;
            let height = image.height;

            if (width >= height && width > maxDimensions.width) {
                height *= maxDimensions.width / width;
                width = maxDimensions.width;
            } else if (height > maxDimensions.height) {
                width *= maxDimensions.height / height;
                height = maxDimensions.height;
            } else return resolve(file); // early exit; no need to resize

            EXIF.getData(image, () => {
                const orientation = EXIF.getTag(image, 'Orientation');
                const imageCanvas = this.drawImageToCanvas(image, orientation, 0, 0, width, height, 'contain');
                if (hasToBlobSupport) imageCanvas.toBlob(blob => resolve(blob), file.type);
                else resolve(this.toBlob(imageCanvas, file.type));
            });
        };

        this.loadImage(image, file);

        return true;
    });

    crop = (file, dimensions) => new Promise((resolve) => {

        if (!this.browserSupport || !file.type.match(/image.*/)) return resolve(file); // early exit - not supported

        if (file.type.match(/image\/gif/)) return resolve(file); // early exit - could be an animated gif

        const image = document.createElement('img');

        image.onload = () => {

            if (dimensions.width > image.width && dimensions.height > image.height) return resolve(file); // early exit - no need to resize

            const width = Math.min(dimensions.width, image.width);
            const height = Math.min(dimensions.height, image.height);

            if (image.width > dimensions.width * 2 || image.height > dimensions.height * 2) {
                return this.resize(file, { width: dimensions.width * 2, height: dimensions.height * 2 }).then((zoomedOutImage) => {
                    this.crop(zoomedOutImage, { width, height }).then(resolve);
                });
            }

            EXIF.getData(image, () => {
                const orientation = EXIF.getTag(image, 'Orientation');
                const imageCanvas = this.drawImageToCanvas(image, orientation, 0, 0, width, height, 'crop');
                if (hasToBlobSupport) imageCanvas.toBlob(blob => resolve(blob), file.type);
                else resolve(this.toBlob(imageCanvas, file.type));
            });
        };

        this.loadImage(image, file);

        return true;
    });

    drawImageToCanvas = (img, orientation = 1, x = 0, y = 0, width = img.width, height = img.height, method = 'contain') => {
        const canvas = document.createElement('canvas');
        const ctx = canvas.getContext('2d');

        canvas.width = width;
        canvas.height = height;

        ctx.save();
        switch (Number(orientation)) {
            // explained here: https://i.stack.imgur.com/6cJTP.gif
            case 1:
                break;

            case 2:
                ctx.translate(width, 0);
                ctx.scale(-1, 1);
                break;

            case 3:
                ctx.translate(width, height);
                ctx.rotate((180 / 180) * Math.PI); // 180/180 is 1? No shit, but how else will you know its need 180 rotation?
                break;

            case 4:
                ctx.translate(0, height);
                ctx.scale(1, -1);
                break;

            case 5:
                canvas.width = height;
                canvas.height = width;
                ctx.rotate((90 / 180) * Math.PI);
                ctx.scale(1, -1);
                break;

            case 6:
                canvas.width = height;
                canvas.height = width;
                ctx.rotate((90 / 180) * Math.PI);
                ctx.translate(0, -height);
                break;

            case 7:
                canvas.width = height;
                canvas.height = width;
                ctx.rotate((270 / 180) * Math.PI);
                ctx.translate(-width, height);
                ctx.scale(1, -1);
                break;

            case 8:
                canvas.width = height;
                canvas.height = width;
                ctx.translate(0, width);
                ctx.rotate((270 / 180) * Math.PI);
                break;

            default:
                break;
        }

        if (method === 'crop') ctx.drawImage(img, (img.width / 2) - (width / 2), (img.height / 2) - (height / 2), width, height, 0, 0, width, height);
        else ctx.drawImage(img, x, y, width, height);
        ctx.restore();

        return canvas;
    };

    toBlob = (canvas, type) => {
        const dataURI = canvas.toDataURL(type);
        const dataURIParts = dataURI.split(',');
        let byteString;
        if (dataURIParts[0].indexOf('base64') >= 0) {
            byteString = atob(dataURIParts[1]);
        } else {
            byteString = decodeURIComponent(dataURIParts[1]);
        }
        const arrayBuffer = new ArrayBuffer(byteString.length);
        const intArray = new Uint8Array(arrayBuffer);

        for (let i = 0; i < byteString.length; i += 1) {
            intArray[i] = byteString.charCodeAt(i);
        }

        const mimeString = dataURIParts[0].split(':')[1].split(';')[0];
        let blob = null;

        if (hasBlobConstructor) {
            blob = new Blob([hasArrayBufferViewSupport ? intArray : arrayBuffer], { type: mimeString });
        } else {
            const bb = new BlobBuilder();
            bb.append(arrayBuffer);
            blob = bb.getBlob(mimeString);
        }

        return blob;
    };

    loadImage = (image, file) => {
        if (typeof (URL) === 'undefined') {
            const reader = new FileReader();
            reader.onload = (event) => {
                image.src = event.target.result;
            };
            reader.readAsDataURL(file);
        } else {
            image.src = URL.createObjectURL(file);
        }
    };

}

I expected the resulting image to be no larger than specified size, but this can happen with the current code. Here is my fixed version:

                if (width >= height && width > maxDimensions.width) {
                    height *= maxDimensions.width / width;
                    width = maxDimensions.width;
                    if (height > maxDimensions.height) {
                        width *= maxDimensions.height / height;
                        height = maxDimensions.height;
                    }
                } else if (height > maxDimensions.height) {
                    width *= maxDimensions.height / height;
                    height = maxDimensions.height;
                    if(width > maxDimensions.width) {
                        height *= maxDimensions.width / width;
                        width = maxDimensions.width;
                    }
                } else return resolve(file); // early exit; no need to resize

Basicly, after resizing i.e. by width, check again that the height is within the boundary and resize if not.
i.e. i had an input image with 2048x1536 that should be fit within 240x135. Previous code resulted in an 240x180 pixel image.

@bhelm

2048x1536 should be 240x180.

if 240x135, image will be out of shape

@cnyyk that is the point. I think if i rescale 2048x1536 to 240x135, I expect an 180x135 image as result instead of 240x180. That is because 180x135 fits within the requested 240x135 boundaries while keeping the shape.
My usecase was that I wanted to display multiple thumbnails next to each other. Without the fix, the portrait pictures were larger than the horizontal ones, which looked bad.

Well done man. Thanks! 👍

I notice this calls URL.createObjectURL but doesn't ever release the url. The documentation suggests using URL.revokeObjectURL for every call to createObjectUrl to avoid memory leaks. This can be seen in the "Memory Management" section of this document: https://devdocs.io/dom/url/createobjecturl.

I'm not sure where a good place to call that would be here, but I wonder if calling it after the resolve call would be best.

@SagiMedina Thank you! Works perfectly with Axios and it's fast!

Hello
Reactjs error

./src/Components/ImageTools.js
  Line 192:  'BlobBuilder' is not defined  no-undef

Search for the keywords to learn more about each error.

@enkhee
I changed:

const bb = new BlobBuilder();
bb.append(arrayBuffer);
blob = bb.getBlob(mimeString);

to:

blob = new Blob([arrayBuffer]);

That's what was recommended here and it seems to be working.

thanks for the helpful code, @SagiMedina !

Hey there, I was using @dcollien solution as well and were facing the same rotation issues. But with your code, my Svelte + Rollup setup fails showing the following issue:

[!] (plugin commonjs) SyntaxError: Unexpected token (33:25) in /Users/username/Git/projectname/src/ImageTools.js
src/ImageTools.js (33:25)

33:     isSupportedByBrowser = () => (hasCanvasSupport && hasBlobSupport && hasReaderSupport);
                                                     ^

Any idea?

Hello I'm trying to implement in svelte project, i've imported exif-js
and im getting:

exif.js:741 Uncaught ReferenceError: n is not defined
    at getStringFromDB (exif.js:741:14)
    at readEXIFData (exif.js:748:13)
    at findEXIFinJPEG (exif.js:449:24)
    at handleBinaryFile (exif.js:370:24)
    at fileReader.onload (exif.js:391:21)