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JavaScript: Multiple cropping selection in one image?

PS: Is it not a research kind of question! I have been trying to do this from very long time.
I am trying to make web based an image editor where user can select multiple cropping area and after selection save/download all the image area. like below.
As of now I discovered two libraries
1.Cropper.JS where is only single selection feature is available.
2.Jcrop where only single selection area restrictions.
I am currently using cropper.Js but it seems impossible for me to make multiple selection cropping.
Any help is much appreciated.if any other method/library available in JavaScript, Angular or PHP or reactJS for multiple image area selection and crop and download in one go as in the image below.
As per #Keyhan Answer I am Updating my Jcrop library Code
<div style="padding:0 5%;">
<img id="target" src="https://d3o1694hluedf9.cloudfront.net/market-750.jpg">
</div>
<button id="save">Crop it!</button>
<link rel="stylesheet" href="https://unpkg.com/jcrop/dist/jcrop.css">
<script src="https://unpkg.com/jcrop"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
JavaScript
<script>
setImage();
var jcp;
var jcp;
Jcrop.load('target').then(img => {
//You can enable multiple cropping with this line:
jcp = Jcrop.attach(img, { multi: true });
});
// to fix security issue when trying to convert to Data URI
function setImage() {
document.getElementById('target').setAttribute('crossOrigin', 'anonymous');
document.getElementById('target').src = 'https://d3o1694hluedf9.cloudfront.net/market-750.jpg';
}
var link = document.getElementById('save');
link.onclick = function () {
//we check if at least one crop is available
if (jcp.active) {
var i = 0;
var fullImg = document.getElementById("target");
//we are looping cropped areas
for (area of jcp.crops) {
i++;
//creating temp canvas and drawing cropped area on it
canvas = document.createElement("canvas");
canvas.setAttribute('width', area.pos.w);
canvas.setAttribute('height', area.pos.h);
ctx = canvas.getContext("2d");
ctx.drawImage(fullImg, area.pos.x, area.pos.y, area.pos.w, area.pos.h, 0, 0, area.pos.w, area.pos.h);
//creating temp link for saving/serving new image
temp = document.createElement('a');
temp.setAttribute('download', 'area' + i + '.jpg');
temp.setAttribute('href', canvas.toDataURL("image/jpg").replace("image/jpg", "image/octet-stream"));
temp.click();
}
}
};
</script>

I tried to explain the code with comments:
var jcp;
Jcrop.load('target').then(img => {
//You can enable multiple cropping with this line:
jcp = Jcrop.attach(img,{multi:true});
});
//assuming you have a button with id="save" for exporting cropped areas
var link=document.getElementById('save');
link.onclick = function(){
//we check if at least one crop is available
if(jcp.active){
var i=0;
var fullImg = document.getElementById("target");
//we are looping cropped areas
for(area of jcp.crops){
i++;
//creating temp canvas and drawing cropped area on it
canvas = document.createElement("canvas");
canvas.setAttribute('width',area.pos.w);
canvas.setAttribute('height',area.pos.h);
ctx = canvas.getContext("2d");
ctx.drawImage(fullImg, area.pos.x, area.pos.y, area.pos.w, area.pos.h, 0, 0, area.pos.w, area.pos.h);
//creating temp link for saving/serving new image
temp = document.createElement('a');
temp.setAttribute('download', 'area'+i+'.jpg');
temp.setAttribute('href', canvas.toDataURL("image/jpg").replace("image/jpg", "image/octet-stream"));
temp.click();
}
}
};
EDIT: As you commented it would be nicer if we have local image loader, we can add a file input to our html
<img id="target" />
<br/>
<input type="file" id="imageLoader" name="imageLoader"/><!-- add this for file picker -->
<button id="save">save</button>
and a function to our js to handle it
var jcp;
var save=document.getElementById('save');
var imageLoader = document.getElementById('imageLoader');
var img = document.getElementById("target");
imageLoader.onchange=function handleImage(e){//handling our image picker <input>:
var reader = new FileReader();
reader.onload = function(event){
img.src = event.target.result;
}
reader.readAsDataURL(e.target.files[0]);
}
save.onclick = function(){
if(jcp&&jcp.active){
var i=0;
for(area of jcp.crops){
i++;
canvas = document.createElement("canvas");
canvas.setAttribute('width',area.pos.w);
canvas.setAttribute('height',area.pos.h);
ctx = canvas.getContext("2d");
ctx.drawImage(img, area.pos.x, area.pos.y, area.pos.w, area.pos.h, 0, 0, area.pos.w, area.pos.h);
temp = document.createElement('a');
temp.setAttribute('download', 'area'+i+'.jpg');
temp.setAttribute('href', canvas.toDataURL("image/jpg").replace("image/jpg", "image/octet-stream"));
temp.click();
}
}
};
Jcrop.load('target').then(img => {
jcp = Jcrop.attach(img,{multi:true});
});

Yes, #keyhan was right <input type="file"> is another question, but still, I am giving you an idea of how to implement Kayhan's code above.
<div>
<input type="file" id="image-input" accept="image/*">
<!-- img id name should be "target" as it is also using by Jcrop -->
<img id="target"></img>
</div>
and Now you can put below JavaScript Code just above setImage()
<script>
let imgInput = document.getElementById('image-input');
imgInput.addEventListener('change', function (e) {
if (e.target.files) {
let imageFile = e.target.files[0];
var reader = new FileReader();
reader.onload = function (e) {
var img = document.createElement("img");
img.onload = function (event) {
var MAX_WIDTH = 1600;
var MAX_HEIGHT = 800;
var width = img.width;
var height = img.height;
// Change the resizing logic
if (width > height) {
if (width > MAX_WIDTH) {
height = height * (MAX_WIDTH / width);
width = MAX_WIDTH;
}
} else {
if (height > MAX_HEIGHT) {
width = width * (MAX_HEIGHT / height);
height = MAX_HEIGHT;
}
}
// Dynamically create a canvas element
var canvas = document.createElement("canvas");
canvas.width = width;
canvas.height = height;
// var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// Actual resizing
ctx.drawImage(img, 0, 0, width, height);
// Show resized image in preview element
var dataurl = canvas.toDataURL(imageFile.type);
document.getElementById("target").src = dataurl;
}
img.src = e.target.result;
}
reader.readAsDataURL(imageFile);
}
});
</script>

Upload Image, Resize, Modify, Download with JavaScript

For the most part this is working, except the uploaded image resizes back to its original size within the canvas when text is added. I'll post a couple of example images below for a visual.
Here is the JavaScript:
function upImage(imageFile) {
let imgInput = document.getElementById('imageIn');
imgInput.addEventListener('change', function(e) {
if(e.target.files) {
let imageFile = e.target.files[0]; //here we get the image file
var reader = new FileReader();
reader.readAsDataURL(imageFile);
reader.onloadend = function (e) {
gImgObj = new Image(); // Creates image object
gImgObj.src = e.target.result; // Assigns converted image to image object
gImgObj.onload = function(ev) {
var myCanvas = document.querySelector('.memeCanvas'); // Creates a canvas object
var myContext = myCanvas.getContext("2d"); // Creates a contect object
var MAX_WIDTH = 800;
var MAX_HEIGHT = 600;
var width = gImgObj.width;
var height = gImgObj.height;
if (width > height) {
if (width > MAX_WIDTH) {
height *= MAX_WIDTH / width;
width = MAX_WIDTH;
}
} else {
if (height > MAX_HEIGHT) {
width *= MAX_HEIGHT / height;
height = MAX_HEIGHT;
}
}
myCanvas.width = width;
myCanvas.height = height;
myContext.drawImage(gImgObj, 0, 0, width, height);
}
}
}
});
}
Here is the HTML:
<input id="imageIn" type="file" accept=".jpg,.jpeg,.png" onclick="upImage(this)" onchange="runMemeEditor()"/>
Here is what the initial uploaded image looks like:
Here is what happens when the editor overlay changes:
The call to runMemeEditor() simply loads a few functions which displays a Meme Generator. Like I said, it technically works as designed, but the uploaded image when larger than 800x600 end up resizing back to its original size within the canvas.
Thanks for looking.

Resize image file size by inputted percentage value?

I tried to write script to resize the image file size by the given percentage value. My script is as below:
let canvas;
let array_WH = new Array();
let percent = 50;
let img = new Image();
$(function() {
function ff(height, width, percentage) {
var newHeight = height * (percentage / 100);
var newWidth = width * (percentage / 100);
return [newWidth, newHeight];
}
$("#file_select").change(function(e) {
var fileReader = new FileReader();
fileReader.onload = function(e) {
img.onload = function() {
array_WH = ff(img.width, img.height, percent);
console.log('old width: ' + img.width);
console.log('new width: ' + array_WH[0]);
width = array_WH[0];
height = array_WH[1];
if (canvas) return;
canvas = document.createElement("canvas");
canvas.width = width;
canvas.height = height;
canvas.getContext("2d").drawImage(this, 0, 0, width, height);
// //Line added
var canvasData = canvas.toDataURL();
// //Line edited
this.src = canvasData;
// //Line added
console.log(canvasData.length * 3 / 4, ' bytes');
document.body.appendChild(this); //remove this if you don't want to show it
}
img.src = e.target.result;
}
fileReader.readAsDataURL(e.target.files[0]);
});
});
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.js"></script>
<script src="http://malsup.github.com/jquery.form.js"></script>
<h1 class="logo">Upload Picture</h1>
<div id="upload_form_div">
<form id="upload_form" method="POST" enctype="multipart/form-data" action="upload">
<input type="file" name="file" capture="camera" id="file_select" />
</form>
</div>
<div id="loading" style="display:none;">
Uploading your picture...
</div>
You can FiddleJs for demo here.
Let's say percentage is 50%, therefore function ff(height, width, percentage) {...} supposed to return new width the half of old width, and new height the half of old height, and consequently, the half size of old image size as a result.
However, it does not works the way it is expected. I tested by uploading image file of 3.00 MB (width: 58000px, height: 3867px), then the function produced new image file of 9.5 MB (width: 1933px, height: 2900px), which is far from correct file size that is 1.5 MB the half of old image size.
How could I correct my function to achieve the expected result by the given percentage? Thanks.

1) Changed order in ff call
array_WH = ff(img.height, img.width, percent);
2) Added parameters: type 'image/jpeg' and quality of jpeg 0.5
var canvasData = canvas.toDataURL('image/jpeg', 0.5)
Here is edited fiddle http://jsfiddle.net/2pu4tmkr/

how reduce the memory usage of canvas in mobile browser

I'm trying to implement a feature in our project which will trigger the mobile camera when pressing a capture button from mobile browser, it will append the captured image as canvas to html page, but if we capture more than 2 image, the browser get's restart automatically and showing memory low warning. Please let me know is there any way to optimize the canvas size?.
Note:
I have tested only in mobile chrome.
I'm attaching the sample code below
html code:
<input type="file" id="camera" accept="image/*" capture>
<div id="MediaOutput"></div>
javascript:
var storedMediaList=[];
var mobile_picture = document.querySelector("#camera");
mobile_picture.onchange = function () {
var file = mobile_picture.files[0];
storedMediaList.push({id:(Math.floor(Math.random()*90000)+10000),data:file});
drawImage();
};
function drawImage()
{
$(".rc").remove().empty();
$("#MediaOutput").html("");
$("#MediaOutput").html("<div class='mediaWrapper'></div>");
storedMediaList.forEach(function(row,index,array)
{
$(".mediaWrapper").append("<div style='float:left;' class='ir' id='c"+row.id+"' class='pic'><div media-id="+row.id+" class='close-image' id='close-image' style='width:24px;background:url(images/close.png) no-repeat;height:25px;cursor:pointer;'></div><canvas id='cv"+row.id+"'></canvas> </div>");
var reader = new FileReader();
reader.onload = function (e) {
var dataURL = e.target.result,
c = document.querySelector("#cv"+row.id),
ctx = c.getContext('2d'),
img = new Image();
img.onload = function() {
c.width = img.width;
c.height = img.height;
ctx.drawImage(img, 0, 0);
};
img.src = dataURL;
};
reader.readAsDataURL(row.data);
});
function resizeImage(img, percentage) {
var coeff = percentage/100,
width = $(img).width(),
height = $(img).height();
return {"width": width*coeff, "height": height*coeff}
}
$('.ir canvas').each(function(){
var newDimensions = resizeImage( this, 70);
this.style.width = newDimensions.width + "px";
this.style.height = newDimensions.height + "px";
});
var width = 0;
$('#MediaOutput .mediaWrapper div').each(function() {
width += $(this).outerWidth( true );
});
$('#MediaOutput .mediaWrapper').css('width', width + "px");
}
Thanks in Advance!!

Image resize before upload

I need to provide a means for a user to upload photos to their web site in jpeg format. However, the photos are very large in original size, and I would like to make the resize before upload option very effortless for the user. It seems my only options are a client side application that resizes the photos before uploading them via a web service, or a client side JavaScript hook on the upload operation that resizes the images. The second option is very tentative because I don't have a JavaScript image resizing library, and it will be difficult to get the JavaScript to run my current resize tool, ImageMagick.
I'm sure this is not too uncommon a scenario, and some suggestions or pointers to sites that do this will be appreciated.

In 2011, we can know do it with the File API, and canvas.
This works for now only in firefox and chrome.
Here is an example :
var file = YOUR_FILE,
fileType = file.type,
reader = new FileReader();
reader.onloadend = function() {
var image = new Image();
image.src = reader.result;
image.onload = function() {
var maxWidth = 960,
maxHeight = 960,
imageWidth = image.width,
imageHeight = image.height;
if (imageWidth > imageHeight) {
if (imageWidth > maxWidth) {
imageHeight *= maxWidth / imageWidth;
imageWidth = maxWidth;
}
}
else {
if (imageHeight > maxHeight) {
imageWidth *= maxHeight / imageHeight;
imageHeight = maxHeight;
}
}
var canvas = document.createElement('canvas');
canvas.width = imageWidth;
canvas.height = imageHeight;
var ctx = canvas.getContext("2d");
ctx.drawImage(this, 0, 0, imageWidth, imageHeight);
// The resized file ready for upload
var finalFile = canvas.toDataURL(fileType);
}
}
reader.readAsDataURL(file);

There is multiple-technology-capable Plupload tool which declares that it can do resizing before upload, but I haven't tried it yet. I have also find a suitable answer in my question about binary image handling javascript libs.

You have several options:
Java
ActiveX (only on windows)
Silverlight
Flash
Flex
Google Gears (the most recent version is capable of resizing and drag and drop from your desktop)
I've done a lot of research looking for a similar solution to what you have described and there a lot of solutions out there that vary a lot in quality and flexibility.
My suggestion is find a solution which will do 80% of what you need and customize it to suit your needs.

I think you need Java or ActiveX for that. For example Thin Image Upload

What jao and russau say is true. The reason being is JavaScript does not have access to the local filesystem due to security reasons. If JavaScript could "see" your image files, it could see any file, and that is dangerous.
You need an application-level control to be able to do this, and that means Flash, Java or Active-X.

Unfortunately you won't be able to resize the images in Javascript. It is possible in Silverlight 2 tho.
If you want to buy something already done: Aurigma Image Uploader is pretty impressive - $USD250 for the ActiveX and Java versions. There's some demos on the site, I'm pretty sure facebook use the same control.

Here some modifications to feed tensorflow.js(soo fast with it!!) with resized and cropped image (256x256px), plus showing original image under cropped image, to see what is cut off.
$("#image-selector").change(function(){
var file = $("#image-selector").prop('files')[0];
var maxSize = 256; // well now its minsize
var reader = new FileReader();
var image = new Image();
var canvas = document.createElement('canvas');
var canvas2 = document.createElement('canvas');
var dataURItoBlob = function (dataURI) {
var bytes = dataURI.split(',')[0].indexOf('base64') >= 0 ?
atob(dataURI.split(',')[1]) :
unescape(dataURI.split(',')[1]);
var mime = dataURI.split(',')[0].split(':')[1].split(';')[0];
var max = bytes.length;
var ia = new Uint8Array(max);
for (var i = 0; i < max; i++)
ia[i] = bytes.charCodeAt(i);
return new Blob([ia], { type: mime });
};
var resize = function () {
var width = image.width;
var height = image.height;
if (width > height) {
if (width > maxSize) {
width *= maxSize / height;
height = maxSize;
}
} else {
if (height > maxSize) {
height *= maxSize / width;
width = maxSize;
}
}
if (width==height) { width = 256; height = 256; }
var posiw = 0;
var posih = 0;
if (width > height) {posiw = (width-height)/2; }
if (height > width) {posih = ((height - width) / 2);}
canvas.width = 256;
canvas.height = 256;
canvas2.width = width;
canvas2.height = height;
console.log('iw:'+image.width+' ih:'+image.height+' w:'+width+' h:'+height+' posiw:'+posiw+' posih:'+posih);
canvas.getContext('2d').drawImage(image, (-1)*posiw, (-1)*posih, width, height);
canvas2.getContext('2d').drawImage(image, 0, 0, width, height);
var dataUrl = canvas.toDataURL('image/jpeg');
var dataUrl2 = canvas2.toDataURL('image/jpeg');
if ($("#selected-image").attr("src")) {
$("#imgspeicher").append('<div style="width:100%; border-radius: 5px; background-color: #eee; margin-top:10px;"><div style="position: relative; margin:10px auto;"><img id="selected-image6" src="'+$("#selected-image").attr("src")+'" style="margin: '+document.getElementById('selected-image').style.margin+';position: absolute; z-index: 999;" width="" height=""><img id="selected-image2" src="'+$("#selected-image2").attr("src")+'" style="margin: 10px; opacity: 0.4;"></div><div class="row" style="margin:10px auto; text-align: left;"> <ol>'+$("#prediction-list").html()+'</ol> </div></div>');
}
$("#selected-image").attr("src",dataUrl);
$("#selected-image").width(256);
$("#selected-image").height(256);
$("#selected-image").css('margin-top',posih+10+'px');
$("#selected-image").css('margin-left',posiw+10+'px');
$("#selected-image2").attr("src",dataUrl2);
$("#prediction-list").empty();
console.log("Image was loaded, resized and cropped");
return dataURItoBlob(dataUrl);
};
return new Promise(function (ok, no) {
reader.onload = function (readerEvent) {
image.onload = function () { return ok(resize()); };
image.src = readerEvent.target.result;
};
let file = $("#image-selector").prop('files')[0];
reader.readAsDataURL(file);});});
Html implementation:
<input id ="image-selector" class="form-control border-0" type="file">
<div style="position: relative; margin:10px auto; width:100%;" id="imgnow">
<img id="selected-image" src="" style="margin: 10px; position: absolute; z-index: 999;">
<img id="selected-image2" src="" style="margin: 10px; opacity: 0.4;">
</div>
Also not resize to a maximum width/height, but to minimum. We get a 256x256px square image.

Pure JavaScript solution. My code resizes JPEG by bilinear interpolation, and it doesn't lose exif.
https://github.com/hMatoba/JavaScript-MinifyJpegAsync
function post(data) {
var req = new XMLHttpRequest();
req.open("POST", "/jpeg", false);
req.setRequestHeader('Content-Type', 'image/jpeg');
req.send(data.buffer);
}
function handleFileSelect(evt) {
var files = evt.target.files;
for (var i = 0, f; f = files[i]; i++){
var reader = new FileReader();
reader.onloadend = function(e){
MinifyJpegAsync.minify(e.target.result, 1280, post);
};
reader.readAsDataURL(f);
}
}
document.getElementById('files').addEventListener('change', handleFileSelect, false);

You can resize the image in the client-side before uploading it using an image processing framework.
Below I used MarvinJ to create a runnable code based on the example in the following page:
"Processing images in client-side before uploading it to a server"
Basically I use the method Marvin.scale(...) to resize the image. Then, I upload the image as a blob (using the method image.toBlob()). The server answers back providing a URL of the received image.
/***********************************************
* GLOBAL VARS
**********************************************/
var image = new MarvinImage();
/***********************************************
* FILE CHOOSER AND UPLOAD
**********************************************/
$('#fileUpload').change(function (event) {
form = new FormData();
form.append('name', event.target.files[0].name);
reader = new FileReader();
reader.readAsDataURL(event.target.files[0]);
reader.onload = function(){
image.load(reader.result, imageLoaded);
};
});
function resizeAndSendToServer(){
$("#divServerResponse").html("uploading...");
$.ajax({
method: 'POST',
url: 'https://www.marvinj.org/backoffice/imageUpload.php',
data: form,
enctype: 'multipart/form-data',
contentType: false,
processData: false,
success: function (resp) {
$("#divServerResponse").html("SERVER RESPONSE (NEW IMAGE):<br/><img src='"+resp+"' style='max-width:400px'></img>");
},
error: function (data) {
console.log("error:"+error);
console.log(data);
},
});
};
/***********************************************
* IMAGE MANIPULATION
**********************************************/
function imageLoaded(){
Marvin.scale(image.clone(), image, 120);
form.append("blob", image.toBlob());
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://www.marvinj.org/releases/marvinj-0.8.js"></script>
<form id="form" action='/backoffice/imageUpload.php' style='margin:auto;' method='post' enctype='multipart/form-data'>
<input type='file' id='fileUpload' class='upload' name='userfile'/>
</form><br/>
<button type="button" onclick="resizeAndSendToServer()">Resize and Send to Server</button><br/><br/>
<div id="divServerResponse">
</div>