Move object within canvas boundary limit

canvas.on('object:moving', function (e) {
  var obj = e.target;
  // if object is too big ignore
  if(obj.currentHeight > obj.canvas.height || obj.currentWidth > obj.canvas.width){
    return;
  }
  obj.setCoords();
  // top-left  corner
  if(obj.getBoundingRect().top < 0 || obj.getBoundingRect().left < 0){
    obj.top = Math.max(obj.top, obj.top-obj.getBoundingRect().top);
    obj.left = Math.max(obj.left, obj.left-obj.getBoundingRect().left);
  }
  // bot-right corner
  if(obj.getBoundingRect().top+obj.getBoundingRect().height  > obj.canvas.height || obj.getBoundingRect().left+obj.getBoundingRect().width  > obj.canvas.width){
    obj.top = Math.min(obj.top, obj.canvas.height-obj.getBoundingRect().height+obj.top-obj.getBoundingRect().top);
    obj.left = Math.min(obj.left, obj.canvas.width-obj.getBoundingRect().width+obj.left-obj.getBoundingRect().left);
  }
});

Here you can find solution:-

var canvas = window._canvas = new fabric.Canvas('c');
canvas.selection = false;

fabric.Object.prototype.set({
    transparentCorners: false,
    cornerColor: 'red',
    cornerSize: 12,
    padding: 0
});
text = new fabric.Text('Sample',{
    top: canvas.height/2,
    left: canvas.width/2,
    fill: '#000000'
});

canvas.add(text);
canvas.setActiveObject(text);

canvas.observe('object:scaling', function (e) {
    var obj = e.target;
  if(obj.getHeight() > obj.canvas.height || obj.getWidth() > obj.canvas.width){
    obj.setScaleY(obj.originalState.scaleY);
    obj.setScaleX(obj.originalState.scaleX);        
  }
  obj.setCoords();
  if(obj.getBoundingRect().top - (obj.cornerSize / 2) < 0 || 
     obj.getBoundingRect().left -  (obj.cornerSize / 2) < 0) {
    obj.top = Math.max(obj.top, obj.top-obj.getBoundingRect().top + (obj.cornerSize / 2));
    obj.left = Math.max(obj.left, obj.left-obj.getBoundingRect().left + (obj.cornerSize / 2));    
  }
  if(obj.getBoundingRect().top+obj.getBoundingRect().height + obj.cornerSize  > obj.canvas.height || obj.getBoundingRect().left+obj.getBoundingRect().width + obj.cornerSize  > obj.canvas.width) {

    obj.top = Math.min(obj.top, obj.canvas.height-obj.getBoundingRect().height+obj.top-obj.getBoundingRect().top - obj.cornerSize / 2);
    obj.left = Math.min(obj.left, obj.canvas.width-obj.getBoundingRect().width+obj.left-obj.getBoundingRect().left - obj.cornerSize /2);    
  }
});

canvas.observe('object:moving', function (e) {
    var obj = e.target;
  if(obj.getHeight() > obj.canvas.height || obj.getWidth() > obj.canvas.width){
    obj.setScaleY(obj.originalState.scaleY);
    obj.setScaleX(obj.originalState.scaleX);        
  }
  obj.setCoords();
  if(obj.getBoundingRect().top - (obj.cornerSize / 2) < 0 || 
     obj.getBoundingRect().left -  (obj.cornerSize / 2) < 0) {
    obj.top = Math.max(obj.top, obj.top-obj.getBoundingRect().top + (obj.cornerSize / 2));
    obj.left = Math.max(obj.left, obj.left-obj.getBoundingRect().left + (obj.cornerSize / 2));    
  }
  if(obj.getBoundingRect().top+obj.getBoundingRect().height + obj.cornerSize  > obj.canvas.height || obj.getBoundingRect().left+obj.getBoundingRect().width + obj.cornerSize  > obj.canvas.width) {

    obj.top = Math.min(obj.top, obj.canvas.height-obj.getBoundingRect().height+obj.top-obj.getBoundingRect().top - obj.cornerSize / 2);
    obj.left = Math.min(obj.left, obj.canvas.width-obj.getBoundingRect().width+obj.left-obj.getBoundingRect().left - obj.cornerSize /2);    
  }
});

http://jsfiddle.net/jw1827fm/1/