Develop Reference

Event handler for object selection on fabricjs canvas

I have a canvas that has some elements and i would like to add an event handler when the user selects an element(clicks on an element) on the canvas.
I tried using selection: created and object: selected events to handle the same but It only works when a user selects an element and then clicks on somewhere else in the canvas and then tries to select another element it works perfectly, But When the user clicks on one element(event handler triggered) and then clicks on another element the event handler is not triggering. How do I handle this?
i see that there is an option to use as mentioned here in the issue with selection:created and
selection:updated https://github.com/fabricjs/fabric.js/issues/4886
But is there a way i could use them together ?
const canvas = new fabric.Canvas('paper', {
preserveObjectStacking: true,
enableRetinaScaling: false,
imageSmoothingEnabled: false
});
canvas.setHeight(500);
canvas.setWidth(700);
const red = new fabric.Rect({
id: 'red',
left: 10,
top: 10,
width: 100,
height: 100,
fill: 'red'
});
const green = new fabric.Rect({
id: 'green',
left: 150,
top: 150,
width: 100,
height: 100,
fill: 'green'
});
canvas.add(red);
canvas.add(green);
canvas.renderAll();
canvas.on("selection:created", function(obj){
alert(obj.target.id)
});
canvas.on("selection:updated", function(obj){
alert(obj.target.id)
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/2.2.3/fabric.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<canvas id="paper" width="400" height="400" style="border:1px solid #ccc"></canvas>

Here is a pretty simple solution for having both the event handlers combined and linking both of them to the same method will be a simple solution for this, Any better solutions will be appreciated.
canvas.on({
'selection:updated': HandleElement,
'selection:created': HandleElement
});
function HandleElement(obj){
//Handle the object here
}

Paste image from clipboard to fabric.js canvas?

I'm trying to create a function that pastes an image from the user's clipboard to the canvas as a new fabric.Image(). Any search result I find either describes cloning objects already on the canvas or pasting IText data. This SO question is related to what I'm asking about, but it's 4 years old and the function in the top answer doesn't work:
How to do Copy and paste the image from User system to Canvas using fabric.js
Here's the code I'm currently trying to use. I'm trying to set up a paste function I can call later:
var $wrapper = $('#content'),
canvas = new fabric.Canvas('canvas', {
width: 400,
height: 550
}),
pasteImage = function (e) {
var items=e.originalEvent.clipboardData.items;
e.preventDefault();
e.stopPropagation();
// Fabric.js image function
function canvasImage(url) {
var img = new fabric.Image(url);
img.scale(0.75).center().setCoords();
canvas.add(img).renderAll();
}
//Loop through files
for(var i=0;i<items.length;i++){
var file = items.items[i],
type = file.type;
if (type.indexOf("image")!=-1) {
var imageData = file.getAsFile();
var imageURL=window.webkitURL.createObjectURL(imageData);
canvasImage(imageURL);
}
}
};
$wrapper.on('paste', pasteImage);
Here's a fiddle to see it in action (or inaction, I guess). This will eventually be part of a Photoshop plugin, so thankfully I only need to worry about this working in Chrome.

I couldn't get your paste event handler to trigger, because i'm not sure if div can natively take the past event unless you make it a contenteditable div, which in your use case i doubt you want to do.
I just recently implemented this in an app of my own, but i wasn't using fabric, just native canvas and js.
You're going to have to rework your code, but try changing
$wrapper.on('paste', pasteImage);
to
$(window).on('paste', pasteImage);
Regardless, I tinkered with your current code, and this is what I got to work, albeit it might not have your settings being triggered completely, but it is pasting the image in:
(function() {
var $wrapper = $('#content'),
canvas = new fabric.Canvas('canvas', {
width: 400,
height: 550
}),
txtStyles = {
top: 100,
left: 200,
padding: 6,
fill: '#d6d6d6',
fontFamily: 'sans-serif',
fontSize: '24',
originY: 'center',
originX: 'center',
borderColor: '#d6d6d6',
cornerColor: '#d6d6d6',
cornerSize: 5,
cornerStyle: 'circle',
transparentCorners: false,
lockUniScaling: true
},
imgAttrs = {
left: 200,
top: 200,
originY: 'center',
originX: 'center',
borderColor: '#d6d6d6',
cornerColor: '#d6d6d6',
cornerSize: 5,
cornerStyle: 'circle',
transparentCorners: false,
lockUniScaling: true
},
introTxt = new fabric.Text('Paste images here', txtStyles),
pasteImage = function (e) {
var items=e.originalEvent.clipboardData.items;
e.preventDefault();
e.stopPropagation();
//Loop through files
for(var i=0;i<items.length;i++){
if (items[i].type.indexOf('image')== -1) continue;
var file = items[i],
type = items[i].type;
var imageData = file.getAsFile();
var URLobj = window.URL || window.webkitURL;
var img = new Image();
img.src = URLobj.createObjectURL(imageData);
fabric.Image.fromURL(img.src, function(img){
canvas.add(img);
});
}
},
//Canvas starter text
introCanvas = function() {
canvas.add(introTxt);
};
introCanvas();
$(window).on('paste', pasteImage);
})();
fiddlers: https://jsfiddle.net/c0kw5dbu/3/

Is it possible to make a dynamic mask/crop system via fabric.js that behaves like canva.com?

edit 2016, Oct 24
I've an idea about this feature by using 'pattern' which seems to be a good idea.
I tried to prove my thoughts with this pen, its still buggy but at least we can set the image(pattern) position and keep the original image when double click.
I'am not very good at javascript, So if you are interest in this please help to make this more useable, any discussions/thoughts or code correction is welcome.
http://codepen.io/wushan/pen/LRrQEL?editors=1010
// Create Canvas
var canvas = this.__canvas = new fabric.CanvasEx('c', {
preserveObjectStacking: true
});
fabric.Object.prototype.transparentCorners = false;
// Global Settings
var url = "http://fabricjs.com/assets/pug.jpg";
//Make the Pattern by url
function createMaskedImage(url) {
//Load Image
fabric.Image.fromURL(url, function(img) {
img.scaleToWidth(300);
//Make a Pattern
var patternSourceCanvas = new fabric.StaticCanvas();
patternSourceCanvas.add(img);
var pattern = new fabric.Pattern({
source: function() {
patternSourceCanvas.setDimensions({
width: img.getWidth(),
height: img.getHeight()
});
return patternSourceCanvas.getElement();
},
repeat: 'no-repeat'
});
console.log(pattern.offsetX)
console.log(pattern.offsetY)
console.log(img.getWidth()) // 縮小後 (*scale)
console.log(img.width) // 原尺寸
//Mask (can be any shape ex: Polygon, Circles....)
var rect = new fabric.Rect({
width: 200,
height: 200,
left: 150,
top: 100,
fill: pattern
})
//Bind Double Click Event from fabric.ext
//https://github.com/mazong1123/fabric.ext
rect.on('object:dblclick', function (options) {
//Pass pattern out
enterEditMode(rect, img);
});
canvas.add(rect);
canvas.setActiveObject(rect);
});
}
function enterEditMode(mask, image) {
image.left = mask.left;
image.top = mask.top;
// New Image
// Fake Crop Area (fixed)
var rect = new fabric.Rect({
width: mask.width,
height: mask.height,
left: mask.left,
top: mask.top,
fill: '#000000',
opacity: 0.8,
selectable: false
})
canvas.remove(mask);
canvas.add(image);
image.on('object:dblclick', function (options) {
//Flatten
flatten(rect, image);
});
canvas.add(rect);
// console.log(JSON.stringify(canvas));
}
function flatten(mask, image) {
//Make a Pattern
var patternSourceCanvas = new fabric.StaticCanvas();
patternSourceCanvas.add(image);
var pattern = new fabric.Pattern({
source: function() {
patternSourceCanvas.setDimensions({
width: image.getWidth(),
height: image.getHeight()
});
return patternSourceCanvas.getElement();
},
repeat: 'no-repeat'
});
//Offsets
pattern.offsetX = image.left - mask.left - image.left;
pattern.offsetY = image.top - mask.top - image.top;
var rect = new fabric.Rect({
width: mask.width,
height: mask.height,
left: mask.left,
top: mask.top,
fill: pattern
})
//Bind Double Click Event from fabric.ext
//https://github.com/mazong1123/fabric.ext
rect.on('object:dblclick', function (options) {
//Pass pattern out
enterEditMode(rect, image);
});
canvas.remove(mask);
canvas.remove(image);
canvas.add(rect);
canvas.setActiveObject(rect);
canvas.renderAll();
}
//Button Events
//Create
document.getElementById('createMaskedImage').addEventListener('click', function () {
createMaskedImage(url);
});
Test this :
click 'create'
double click on the image object
move/scale the image
double click the image to flatten the obejct.
Know issue:
when cutting the image without scale, the image position looks correct but there is a wired transparent space.
It generates a lot duplicate objects on the scene...
Original Post
I've been working with fabric.js for a few month, haven't seen any example or discussions about a mask/crop system which is behaves like canva.com ( which is way easy to understand for users. )
the object looks like this:
when double clicked on a group/mask, it shows the original image with an unselectable mask, you can move/scale the image whatever you need and click 'OK' to made the change without modifying the original image.
I'd like to know if there is any possible solutions about making this in fabricjs, or maybe some thoughts about this issue is welcome.
Thank you a lot !

FabricJS adding Image to Group causes odd control behavior

I'm attempting to add a loaded image into a fabric Group object. Everything looks ok, but the selection controls aren't selectable and I can't drag the object around. The top left control works though and after clicking it everything is fine.
Here is a jsfiddle that demonstrates the behavior.
var canvas = new fabric.Canvas('canvas', {
width: 200,
height: 200
});
var group = new fabric.Group();
canvas.add(group);
fabric.Image.fromURL('https://placehold.it/100x100', function(img) {
group.addWithUpdate(img);
canvas.setActiveObject(group);
canvas.renderAll();
});
Is this a bug or am I doing something wrong?

For some performance reason, fabricjs does not call setCoords automatically after adding objects to a group ( in case of many object added you can call setCoords just once ).
So after doing addWithUpdate, just call group.setCoords();
var canvas = new fabric.Canvas('canvas', {
width: 200,
height: 200
});
var group = new fabric.Group();
canvas.add(group);
fabric.Image.fromURL('https://placehold.it/100x100', function(img) {
group.addWithUpdate(img);
group.setCoords();
canvas.setActiveObject(group);
canvas.renderAll();
});

I came across this post because I was having trouble getting the positioning of images to work properly. I ended up finding that it's easier to just create create an image element using document.createElement and set the src, then feed that into fabric.Image with all the options you need (instead of using fabric.Image.fromURL which was too much of a headache to use), before adding it to the group.
var oImg = document.createElement("img");
oImg.setAttribute('src', 'https://upload.wikimedia.org/wikipedia/commons/thumb/9/92/Cog_font_awesome.svg/512px-Cog_font_awesome.svg.png');
var i = new fabric.Image(oImg, {
originX: 'center',
originY: 'center',
left: left+35,
top: top-30,
scaleX:.05,
scaleY:.05,
});
g = new fabric.Group([r, t, i]); // where r and t are other fabric objects

Let user delete a selected fabric js object

I have a simple fabric js based application where I will let users add shapes connect them and animate them.
Following is my JS
var canvas;
window.newAnimation = function(){
canvas = new fabric.Canvas('canvas');
}
window.addRect = function(){
var rect = new fabric.Rect({
left: 100,
top: 100,
fill: 'red',
width: 20,
height: 20,
});
canvas.add(rect);
}
window.addCircle = function(){
var circle = new fabric.Circle({
radius: 20, fill: 'green', left: 100, top: 100
});
canvas.add(circle);
}
This is my Fiddle. You can click on new animation and then add objects as of now.
I want the user to select some object and then also be able to delete it I am not sure how. I found this Delete multiple Objects at once on a fabric.js canvas in html5 But i was not able to implement it successfully. I basically want users to be able to select an object and delete it.

Since new version of fabric.js was released - you should use:
canvas.remove(canvas.getActiveObject());

Edit: This is for older versions now.
You can use the remove() method, eg.
window.deleteObject = function() {
canvas.getActiveObject().remove();
}
jsfiddle

Delete all selected objects:
canvas.getActiveObjects().forEach((obj) => {
canvas.remove(obj)
});
canvas.discardActiveObject().renderAll()

I am using Fabric JS 2.3.6.
I wanted to allow the user to select one or more objects on the canvas and delete them by clicking the delete button.
Removed methods from old versions
The following methods are no longer available since the introduction of ActiveSelection:
setActiveGroup(group);
getActiveGroup();
deactivateAll();
discardActiveGroup();
deactivateAllWithDispatch();
Here is my code that works great for me and hopefully you as well.
$('html').keyup(function(e){
if(e.keyCode == 46) {
deleteSelectedObjectsFromCanvas();
}
});
function deleteSelectedObjectsFromCanvas(){
var selection = canvas.getActiveObject();
if (selection.type === 'activeSelection') {
selection.forEachObject(function(element) {
console.log(element);
canvas.remove(element);
});
}
else{
canvas.remove(selection);
}
canvas.discardActiveObject();
canvas.requestRenderAll();
}

It's pretty simple actually.
Just use Fabric's event handling to manage the object selection, and then fire the delete function for whatever object is selected.
I'm using the canvas selection events to cover all the objects of the canvas. The idea is to add a delete button, keeping it hidden unless needed, and then handling its display on canvas selection events.
Deletion is made easy with the help of remove property of the Fabric library, which obviously triggers when the delete button is clicked.
Here is some sample code to demo what I said above.
// Grab the required elements
var canvas = new fabric.Canvas('c'),
delBtn = document.getElementById('delete')
// Hide the delete button until needed
delBtn.style.display = 'none'
// Initialize a rectangle object
var rect = new fabric.Rect({
left: 100,
top: 100,
fill: 'red',
width: 100,
height: 50
})
// Initialize a circle object
var circle = new fabric.Circle({
left: 250,
top: 100,
radius: 20,
fill: 'purple'
})
// Add objects to the canvas
canvas.add(rect)
canvas.add(circle)
// When a selection is being made
canvas.on({
'selection:created': () => {
delBtn.style.display = 'inline-block'
}
})
// When a selection is cleared
canvas.on({
'selection:cleared': () => {
delBtn.style.display = 'none'
}
})
// Rmove the active object on clicking the delete button
delBtn.addEventListener('click', e => {
canvas.remove(canvas.getActiveObject())
})
body {
background-color: #eee;
color: #333;
}
#c {
background-color: #fff;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/4.4.0/fabric.min.js"></script>
<h4>Select an object</h4>
<canvas id="c" width="600" height="200"></canvas>
<input type="button" id="delete" value="Delete selection">
Easy, wasn't it? Cheers!

On further improving #Rahul answer, we can also support deletion of selected object using key events like 'Delete', 'Backscape'.
// Grab the required elements
var canvas = new fabric.Canvas('c'),
delBtn = document.getElementById('delete'),
wrapper= document.getElementById('canvasWrapper')
// Hide the delete button until needed
delBtn.style.display = 'none'
// Initialize a rectangle object
var rect = new fabric.Rect({
left: 100,
top: 100,
fill: 'red',
width: 100,
height: 50
})
// Initialize a circle object
var circle = new fabric.Circle({
left: 250,
top: 100,
radius: 20,
fill: 'purple'
})
// Add objects to the canvas
canvas.add(rect)
canvas.add(circle)
// When a selection is being made
canvas.on({
'selection:created': () => {
delBtn.style.display = 'inline-block'
}
})
// When a selection is cleared
canvas.on({
'selection:cleared': () => {
delBtn.style.display = 'none'
}
})
// Rmove the active object on clicking the delete button
delBtn.addEventListener('click', e => {
canvas.remove(canvas.getActiveObject())
})
//Remove using keyboard events
wrapper.addEventListener('keyup', e => {
if (
e.keyCode == 46 ||
e.key == 'Delete' ||
e.code == 'Delete' ||
e.key == 'Backspace'
) {
if (canvas.getActiveObject()) {
if (canvas.getActiveObject().isEditing) {
return
}
canvas.remove(canvas.getActiveObject())
}
}
})
body {
background-color: #eee;
color: #333;
}
#c {
background-color: #fff;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/4.4.0/fabric.min.js"></script>
<h4>Select an object</h4>
<div tabIndex="1000"id="canvasWrapper" #keyup="checkDelete($event)" >
<canvas id="c" width="600" height="200"></canvas>
</div>
<input type="button" id="delete" value="Delete selection">

Delete object in Fabricjs. This works completely fine.
this.canvas.getActiveObjects().forEach((o) => {
this.canvas.remove(o);
});

you can delete active object by using backspace key
$(document).keydown(function(event){
if (event.which == 8) {
if (canvas.getActiveObject()) {
canvas.getActiveObject().remove();
}
}
});