Change generated image resolution Fabric.js

Question

I'm creating a Fabric.js based image editor, but I have a problem with final image resolution. I need generated image in high resolution but dimension for my editor are in pixel in low resolution.

For example: canvas has 800px x 600px and I need an final image with 100 cm x 400 cm, in other words, in real size.

Answer 1

Let me put some idea from my experience here -

1. if the final resolution is large, but not extreme large, you can do zoom canvas to its size before generate image data (toDataURL, for instance)
2. if the final resolution is extreme large, I suggest you can deal with it from PHP directly

For the first one -

    var originWidth = canvas.getWidth();

    function zoom (width)
        {
            var scale = width / canvas.getWidth();
            height = scale * canvas.getHeight();

            canvas.setDimensions({
                "width": width,
                "height": height
            });

            canvas.calcOffset();
            var objects = canvas.getObjects();
            for (var i in objects) {
                var scaleX = objects[i].scaleX;
                var scaleY = objects[i].scaleY;
                var left = objects[i].left;
                var top = objects[i].top;

                objects[i].scaleX = scaleX * scale;
                objects[i].scaleY = scaleY * scale;
                objects[i].left = left * scale;
                objects[i].top = top * scale;

                objects[i].setCoords();
            }
            canvas.renderAll();
    }

    zoom (2000);

    // here you got width = 2000 image
    var imageData = canvas.toDataURL({
            format: 'jpeg',
            quality: 1
        });
    zoom (originWidth);

I never tried it on 100cm x 400cm, because it's really large, so if you can't do it from fabric.js, do it in PHP or else, this link may be help Convert SVG image to PNG with PHP

100cm = 39.3inch and 400cm = 39.3 * 4inch, if you have 300dpi image for final output. You will need width = 39.3 * 300 and height 39.3 * 4 * 300 size, if browser can handle it or not, I am not sure.