How to create undo-redo in kineticjs?

@elisha_langworth 

To create undo-redo functionality in a KineticJS canvas, you can follow these steps:

1. Create a stack to store actions: You will need two stacks, one for storing actions that have been performed (undo stack) and one for storing actions that have been undone (redo stack).

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var undoStack = [];
var redoStack = [];

1. Push actions to the undo stack: Whenever a user performs an action on the canvas, such as drawing a shape or moving an object, push that action to the undo stack.

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// For example, if you draw a shape
var shape = new Kinetic.Rect({...});
layer.add(shape);
stage.draw();
undoStack.push(function() {
  shape.remove();
  layer.draw();
});

1. Implement undo functionality: When the user wants to undo an action, pop the last action from the undo stack, perform the reverse action, and push it onto the redo stack.

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function undo() {
  if (undoStack.length > 0) {
    var action = undoStack.pop();
    action();
    redoStack.push(action);
  }
}

1. Implement redo functionality: When the user wants to redo an action, pop the last action from the redo stack, perform the action, and push it onto the undo stack.

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function redo() {
  if (redoStack.length > 0) {
    var action = redoStack.pop();
    action();
    undoStack.push(action);
  }
}

1. Call undo and redo functions when needed: You can bind undo and redo functions to keyboard shortcuts, buttons, or any other user interface element.

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document.addEventListener('keydown', function(event) {
  if (event.ctrlKey && event.key === 'z') {
    undo();
  } else if (event.ctrlKey && event.key === 'y') {
    redo();
  }
});

By following these steps, you can implement an undo-redo functionality in your KineticJS canvas.