如何通过拖动角来调整 html5 画布元素的大小并应保持纵横比？

问题描述

这非常适合调整大小，但我还必须在从 TopLeft、TopRight、BottomLeft、Bottomright 拖动时保持纵横比 [应按角点调整大小并保持纵横比][1]

    const canvas = CanvasData.canvas.getBoundingClientRect();
    if (selectedShape === "TopLeft") {
        mousePos = point(e.pageX - canvas.left,e.pageY - canvas.top);
        CanvasData.activeObject.width = CanvasData.activeObject.width + CanvasData.activeObject.x - mousePos.x
        CanvasData.activeObject.height = CanvasData.activeObject.height + CanvasData.activeObject.y - mousePos.y
        CanvasData.activeObject.x = mousePos.x;
        CanvasData.activeObject.y = mousePos.y;
    } else if (selectedShape === "TopCenter") {
        mousePos = point(e.pageX - canvas.left,e.pageY - canvas.top);
        CanvasData.activeObject.height += CanvasData.activeObject.y - mousePos.y;
        CanvasData.activeObject.y = mousePos.y;
    } else if (selectedShape === "TopRight") {
        CanvasData.activeObject.width = mousePos.x - CanvasData.activeObject.x;
        CanvasData.activeObject.height += CanvasData.activeObject.y - mousePos.y;
        CanvasData.activeObject.y = mousePos.y;
    } else if (selectedShape === "LeftCenter") {
        mousePos = point(e.pageX - canvas.left,e.pageY - canvas.top);
        CanvasData.activeObject.width += CanvasData.activeObject.x - mousePos.x;
        CanvasData.activeObject.x = mousePos.x;
    } else if (selectedShape === "BottomLeft") {
        mousePos = point(e.pageX - canvas.left,e.pageY - canvas.top);
        CanvasData.activeObject.width += CanvasData.activeObject.x - mousePos.x;
        CanvasData.activeObject.x = mousePos.x;
        CanvasData.activeObject.height = mousePos.y - CanvasData.activeObject.y;
    } else if (selectedShape === "BottomCenter") {
        mousePos = point(e.pageX - canvas.left,e.pageY - canvas.top);
        CanvasData.activeObject.height = mousePos.y - CanvasData.activeObject.y;
    } else if (selectedShape === "Bottomright") {
        mousePos = point(e.pageX - canvas.left,e.pageY - canvas.top);
        CanvasData.activeObject.width = mousePos.x - CanvasData.activeObject.x;
        CanvasData.activeObject.height = mousePos.y - CanvasData.activeObject.y;
    } else if (selectedShape === "RightCenter") {
        mousePos = point(e.pageX - canvas.left,e.pageY - canvas.top);
        CanvasData.activeObject.width = mousePos.x - CanvasData.activeObject.x;
    }
}```


  [1]: https://i.stack.imgur.com/kP9pP.png

解决方法

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