We Keep Coding

outline and border in fabricjs

I am using fabric.js for canvas shapes. but now i have to add border with outline on these shapes like below. How it is possible in fabricjs??. Or do we have any other js library to get same output?
I want below output:

Why not create a group out of two rectangles? Like so:
var canvas = this.__canvas = new fabric.StaticCanvas('c');
var rectBack = new fabric.Rect({
width: 170,
height: 170,
top: 0,
left: 0,
fill: 'rgba(0,0,255,1.0)',
rx: 2,
ry: 2
});
var outerMargin = 10
var innerOutlineWidth = 4
var innerOutline = new fabric.Rect({
width: 170 - outerMargin - innerOutlineWidth/2,
height: 170 - outerMargin - innerOutlineWidth/2,
top: outerMargin/2,
left: outerMargin/2,
stroke: 'rgba(255,255,255,1.0)',
fill: 'rgba(0,0,0,0.0)',
strokeWidth: innerOutlineWidth,
rx: 10,
ry: 10
});
var group = new fabric.Group([rectBack, innerOutline], {
left: 0,
top: 0,
angle: 0
});
canvas.add(group);
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/2.7.0/fabric.min.js"></script>
<canvas id="c" width="200" height="200"></canvas>
Any framework you use is going to have some fundamental building blocks you have to piece together to get what you want. So I would not recommend jumping to another one.

unchange the object order

We put the object1 first,then put the object2,and put the object3 finally on the canvas.
It's mean that object1 is on the bottom,and object3 is on the top.
When we want to change the object2 url or do sth on it,we remove it and add the new object2 after.
But now object2 is on the top.
I know some method like sendToBack(),moveTo(),....etc,can change the order of the object2.
There is no clue about fix the object order.
Is there some method already existed or other statement can apply?
If not,is the only way that we change their order again and again by applying method as above after change the object layer?
Thank you.

Use insertAt() to insert the object at given index.
DEMO
var canvas = new fabric.Canvas('c');
var rect1 = new fabric.Rect({
width: 100,
height: 100,
left: 10,
top: 10,
fill: 'red',
});
var rect2 = new fabric.Rect({
width: 100,
height: 100,
left: 30,
top: 30,
fill: 'green',
});
var rect3 = new fabric.Rect({
width: 100,
height: 100,
left: 50,
top: 50,
fill: 'black',
});
var rect4 = new fabric.Rect({
width: 100,
height: 100,
left: 30,
top: 30,
fill: 'yellow',
});
canvas.add(rect1,rect2,rect3);
function alter(){
var index = canvas.getObjects().indexOf(rect2);
//canvas.remove(rect2);
canvas.insertAt(rect4, index,true);
}
<script src="https://rawgit.com/kangax/fabric.js/master/dist/fabric.js"></script>
<button onclick="alter()">Alter</button>
<canvas id="c" width="600" height="600"></canvas>

Fabric.js: Assigning background color to group

I am trying to set a background color for a group without affecting its contained objects.
So far my code looks like this:
var canvas = new fabric.Canvas('canvas');
var helloText = new fabric.Text('hello', {
fontSize: 30,
top: 10, left: 10,
originX: 0, originY: 0
});
var worldText = new fabric.Text('world!', {
fontSize: 40,
top: 50, left: 100,
originX: 0, originY: 0
});
var group = new fabric.Group([helloText, worldText], {
selectionBackgroundColor: 'red',
backgroundColor: 'blue'
});
canvas.add(group);
A jsFiddle version can be found here.
As you can see from my code, I already tried the attribute backgroundColor yet it only affects contained objects. I would like to achieve an effect similar to selectionBackgroundColor.

Slight tweak, but this should do it for you (relevant code):
var text = new fabric.Group([helloText, worldText], {});
var textBoundingRect = text.getBoundingRect();
var background = new fabric.Rect({
top: textBoundingRect.top,
left: textBoundingRect.left,
width: textBoundingRect.width,
height: textBoundingRect.height,
fill: 'blue'
});
var group = new fabric.Group([background, text], {});
Your JSFiddle updated, https://jsfiddle.net/rekrah/92ss3d86/.

I need to create object group on undo function with fabricjs

I have two canvas objects (Rectungle and Triangle) in group.
Then i need to delete them, then return one of objects to is past position.
Here is two objects and group
var rect1 = new fabric.Rect(
{
id: 1, left: 10, top: 10, width: 100, height: 50, angle: 45, fill: 'red'
});
var tria1 = new fabric.Triangle({
id: 2, left: 200, top: 200, width: 100, height: 50, angle: 20, fill: 'yellow'
});
var objsGroup = new fabric.Group([rect1, tria1], {left: 100, top: 100});
And the whole fiddle here. I separate all steps by alerts https://jsfiddle.net/5js60oec/
UPDATE
Have the next problem. Lets assume that existing object group making some move and rotating before deleting. Then i have to restore it to point before rotating and moving. Thats, i think the main problem.
Actions
objsGroup.top = 200;
objsGroup.left = 200;
canvas.renderAll();
alert('4');
history.push(canvas.getActiveGroup());
objsGroup.setAngle(45);
canvas.renderAll();
Here the full fiddler: https://jsfiddle.net/nppaLetn/1/

For example I am deleting the last added path in my canvas like below
var lastItemIndex = (fabricCanvas.getObjects().length - 1);
var item = fabricCanvas.item(lastItemIndex);
if(item.get('type') === 'path') {
fabricCanvas.remove(item);
fabricCanvas.renderAll();
}
This may help you to accomplish your probs!!! I think so .

How to put canvas within canvas?

I just want to know what is the best way to use multiple canvas in a single page. These canvas can be overlapped on each other.
I tried to search this issue on different form, but wasn't able to find any helpful material. This is what we actually want to do(in the following image). There are 5 canvases, and we want all of them to be fully functional. We can add images, text and draw different things on selected canvas.
We are currently using fabricjs.
If that`s not possible, what is the best solution for achieving something like that ?
Thanks in advance!

Simply use CSS for that.
<div class="wrapper">
<canvas id="background_layer" class="canvas-layer" width="100" height="100"></canvas>
<canvas id="other_layer" class="canvas-layer" width="100" height="100"></canvas>
</div>
<style>
.wrapper { position: relative }
.canvas-layer {
position: absolute; left: 0; top: 0;
}
</style>

I am not sure what you are trying to achieve but you can refer to this Fiddle http://jsfiddle.net/PromInc/ZxYCP/
var img01URL = 'https://www.google.com/images/srpr/logo4w.png';
var img02URL = 'http://fabricjs.com/lib/pug.jpg';
var canvas = new fabric.Canvas('c');
// Note the use of the `originX` and `originY` properties, which we set
// to 'left' and 'top', respectively. This makes the math in the `clipTo`
// functions a little bit more straight-forward.
var clipRect1 = new fabric.Rect({
originX: 'left',
originY: 'top',
left: 180,
top: 10,
width: 200,
height: 200,
fill: '#DDD', /* use transparent for no fill */
strokeWidth: 0,
selectable: false
});
// We give these `Rect` objects a name property so the `clipTo` functions can
// find the one by which they want to be clipped.
clipRect1.set({
clipFor: 'pug'
});
canvas.add(clipRect1);
var clipRect2 = new fabric.Rect({
originX: 'left',
originY: 'top',
left: 10,
top: 10,
width: 150,
height: 150,
fill: '#DDD', /* use transparent for no fill */
strokeWidth: 0,
selectable: false
});
// We give these `Rect` objects a name property so the `clipTo` functions can
// find the one by which they want to be clipped.
clipRect2.set({
clipFor: 'logo'
});
canvas.add(clipRect2);
function findByClipName(name) {
return _(canvas.getObjects()).where({
clipFor: name
}).first()
}
// Since the `angle` property of the Image object is stored
// in degrees, we'll use this to convert it to radians.
function degToRad(degrees) {
return degrees * (Math.PI / 180);
}
var clipByName = function (ctx) {
this.setCoords();
var clipRect = findByClipName(this.clipName);
var scaleXTo1 = (1 / this.scaleX);
var scaleYTo1 = (1 / this.scaleY);
ctx.save();
var ctxLeft = -( this.width / 2 ) + clipRect.strokeWidth;
var ctxTop = -( this.height / 2 ) + clipRect.strokeWidth;
var ctxWidth = clipRect.width - clipRect.strokeWidth;
var ctxHeight = clipRect.height - clipRect.strokeWidth;
ctx.translate( ctxLeft, ctxTop );
ctx.rotate(degToRad(this.angle * -1));
ctx.scale(scaleXTo1, scaleYTo1);
ctx.beginPath();
ctx.rect(
clipRect.left - this.oCoords.tl.x,
clipRect.top - this.oCoords.tl.y,
clipRect.width,
clipRect.height
);
ctx.closePath();
ctx.restore();
}
var pugImg = new Image();
pugImg.onload = function (img) {
var pug = new fabric.Image(pugImg, {
angle: 45,
width: 500,
height: 500,
left: 230,
top: 50,
scaleX: 0.3,
scaleY: 0.3,
clipName: 'pug',
clipTo: function(ctx) {
return _.bind(clipByName, pug)(ctx)
}
});
canvas.add(pug);
};
pugImg.src = img02URL;
var logoImg = new Image();
logoImg.onload = function (img) {
var logo = new fabric.Image(logoImg, {
angle: 0,
width: 550,
height: 190,
left: 50,
top: 50,
scaleX: 0.25,
scaleY: 0.25,
clipName: 'logo',
clipTo: function(ctx) {
return _.bind(clipByName, logo)(ctx)
}
});
canvas.add(logo);
};
logoImg.src = img01URL;
I hope this might help.