A question I see sometimes is how can we know when the layer gets redrawn. Firstly I recommend that you don't sweat about this - Konva does a perfectly good job without you interfering. But if you absolutely have to there is a way. Let's take a look...
There's more to writing code than simply, well, writing code! With anything graphical there is always the potential for runaway development that doesn't plan for the scale ahead. This article is about why you need to consider a model. Take a look...
So you need undo-redo for your project. The uniqueness of your app means there's no perfect out-of-the-box solution. But the good news is that you're here and this blog describes an overall approach that you can adapt to meet your needs.
One of the features that Konva provides is the dragBoundFunc which lets us confine a shape within a rect. But how to make that work for a group where things can get a bit more tricky? Lets take a look...
Whether you need just a small section of a shape or the entire width and height of the view, getting snapshot images is quite straightforward once you know a couple of tricks - lets take a look at them...
So there you are with a shiny new group - with a couple of shapes added to it. Now you want to drag the group. Click-dragging the shapes will move the Group, but click-dragging the empty space doesn't - what gives?
The Konva group is a bit hard to pin-down, almost a normal shape but not quite. Its super-powers can be a bit challenging though once you understand a few fundamentals its got your back. Lets dive in...
The Konva transformer is brilliant at handling what would otherwise take a whole bunch of work to copy. But people either overthink it or don't know its full power and tunability. So lets investigate...