Deep clone transformMatrix, strokeDashArray and styles properties

[asturur]

This will be hardly noticed by anyone.
But still is a bug.

closes #2396.

[asturur]

Added clone for the iText style.
@kangax what do you think?

[asturur]

Added failing tests for the modified properties.
ready to merge for me.

[kangax]

newStyle → clonedStyles

[asturur]

if it happens with styles it will happen with array also.

[kangax]

But styles has objects, array has primitives; can't modify primitives' references

[asturur]

I do not understand what you mean, but the bug is there.
Go to kitchensink, execute this code:

// clear canvas
canvas.clear();

// remove currently selected object
canvas.remove(canvas.getActiveObject());

var transform = [2,0,0,2,4,4];
var strokedash = [3, 3];
// add red rectangle
var rect = new fabric.Rect({
  width: 50,
  height: 50,
  left: 50,
  top: 50,
  fill: 'rgb(255,0,0)',
  transformMatrix: transform,
  strokeDashArray: strokedash,
  stroke: 'black',
  strokeWidth: 2
});

// add green, half-transparent circle
canvas.add(rect);
canvas.add(rect.clone().setFill('blue'));
canvas.add(rect.clone().setFill('green'));

obtain this

then run this code

canvas.getActiveObject().transformMatrix[0] = 1;
canvas.getActiveObject().strokeDashArray[1] = 8;
canvas.renderAll();

and you get this: ( all object get modified )

[kangax]

@asturur not sure I understand the bug here... in your last example, you're changing values of transformMatrix and seeing result rendered, no? Isn't this expected behavior?

[asturur]

i m changing the transformatrix of one rect, and all three are changing.
because in transformMatrix we have reference of the cloned object instead of a new array.

[kangax]

Oh, I didn't realize it's cloned. Of course, you're right.

[kangax]

One last thing — we don't want to use extend for arrays since it does for..in iteration and that kind of iteration doesn't just iterate over indices (0..n) but also anything in Array.prototype, etc. Just do transformMatrix.concat() to create a clone of array.

[asturur]

@kangax done.

[kangax]

+changelog