英文:
Konva/react-konva - restore canvas elements from JSON
问题
我正在创建一个使用React和react-konva以及Konva的绘图板应用程序。目前，当用户单击“保存”按钮时，它会获取绘图板的“截图”（使用toDataUrl方法）。问题是，我想在用户稍后想要继续时还原绘图板（基本上，我想保留矢量图形绘图板）。我发现可以通过ref.current.toJson()方法来实现这一点，因为它将绘图板元素保存为JSON格式。如果我知道最后的JSON状态，我如何还原绘图板？
英文:
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?
答案1
得分: 1
以下是已翻译的内容：
自从你有了棋盘的JSON表示，使用JSON.parse()方法解析JSON字符串，然后将其转换为JavaScript对象，接着使用setState()方法更新棋盘的状态为解析后的数据，最后使用解析后的数据渲染棋盘。
试试这样做：
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>
);
}
在这段代码中，请注意boardData对象包含了一个元素数组，每个元素都以Shape组件的形式呈现。
这应该为您提供了恢复棋盘的基本结构和外观的良好思路和合理的起点，您可以根据特定的数据格式和渲染逻辑调整代码。
请注意，从JSON还原棋盘可能不会在所有情况下完美运行，因为某些属性（如事件处理程序或动画）可能无法在JSON格式中保留。
英文:
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.
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