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I am creating a React application that uses react-konva and Konva for a drawing board. Currently, when the user clicks on the Save button it takes a "screenshot" (using the toDataUrl) of the board. The problem with this is that I would like to restore the board if the user want to continue later (so basically I would like to keep the vector graphic board). I found that this can be done though ref.current.toJson() method because it saves the board elements in a JSON format. How can I restore the board if I know the last state in JSON?

Andy
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Matteo Robert
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  • Do you mean `Konva.js` and `react-konva`? Here's the documentation for Konva on [how to load JSON](https://konvajs.org/docs/data_and_serialization/Simple_Load.html) which may help. – Andy Mar 03 '23 at 14:06
  • Yes, this is what I meant – Matteo Robert Mar 03 '23 at 14:09

1 Answers1

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Since you have the JSON representation of the board, Parse the JSON by using the JSON.parse() method to parse the JSON string then convert it into a JavaScript object, then Update the board's state by using the setState() method to update the board's state with the parsed data and finally you Render the board using the parsed data.

Try this:

const boardData = JSON.parse(jsonData);
this.setState({ boardData });

render() {
  return (
    <Stage width={500} height={500}>
      <Layer>
        <Group>
          {this.state.boardData.elements.map((element, index) => (
            <Shape key={index} {...element} />
          ))}
        </Group>
      </Layer>
    </Stage>
  );
}

In this code, take note that the boardData object contains an array of elements and each is rendered as a Shape component.

This should give you a good idea and provide a reasonable starting point for restoring the board's basic structure and appearance, you can adjust code to render the board based on your specific data format and rendering logic.

Note that restoring the board from JSON may not work perfectly in all cases, since some properties (such as event handlers or animations) may not be preserved in the JSON format.

Smarton
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