My fabric.js sclaing methods don't work after object rotation

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I have a scaling method for my Fabric.js objects, so they don't scale outside of the borders. But when I rotate the objects, the scaling method does not work correctly. My guess is that the scaling method does not take in account that the old top is now the right side of the object. Does someone know how to make it take the rotation in account when scaling?

let scalingProperties = {
    'left': 0,
    'top': 0,
    'scaleX': 0,
    'scaleY': 0
}

export function scaling(e) {
    const shape = e.target;
    const maxWidth = shape.canvas.width;
    const maxHeight = shape.canvas.height;

    //left border
    if(shape.left < 0) {
        shape.left = scalingProperties.left = 0;
        shape.scaleX = scalingProperties.scaleX;
    } else {
        scalingProperties.left = shape.left;
        scalingProperties.scaleX = shape.scaleX;
    }

    //right border
    if((shape.scaleX * shape.width) + shape.left > maxWidth) {
        shape.scaleX = (maxWidth - scalingProperties.left) / shape.width;
    } else {
        scalingProperties.scaleX = shape.scaleX;
    }

    //top border
    if(shape.top < 0) {
        shape.top = scalingProperties.top = 0;
        shape.scaleY = scalingProperties.scaleY;
    } else {
        scalingProperties.top = shape.top;
        scalingProperties.scaleY = shape.scaleY;
    }

    //bottom border
    if((shape.scaleY * shape.height) + shape.top > maxHeight) {
        shape.scaleY = (maxHeight - scalingProperties.top) / shape.height;
    } else {
        scalingProperties.scaleY = shape.scaleY;
    }
}
1 Answers

Let's visualize your problem:

enter image description here

A simple approach for this would be to enlarge the container you use, so its bounds would not be overflown even if the content rotates. The worst-case-senario is when the rotation's amount is (n + 1) * pi / 4, where n is a natural number.

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