How to keep aspect ratio when scaling an image on HTML5 canvas?

Question

In my project, I use HTML5 Canvas and FabricJS. I have a script to maintain aspect ratio for an image object that I placed in the canvas. when adjusting the angles or scaling the image, I have to update the width or height to maintain the aspect ratio of the image.

The above image will clearly show my problem. I need an algorithm or formula to preserve the aspect of the image.

The image should match the following,

• If I shrink by adjusting the width or height of the image from the actual size, it will crop and display the image in the same format.
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Answer 1

, :

lockUniScaling: true

, , , :

centeredScaling: true

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- , - (, , , ..), clipTo . : Fabric.js

- JS

Answer 2

HTML5, CSS3 :

canvas {
    -ff-transform: scale(2); 
    -ms-transform: scale(2); 
    -webkit-transform: scale(2); 
}

CSS3 .

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CSS3 : https://developer.mozilla.org/en-US/docs/Web/CSS/transform