Display settings zoom and browser zoom

[TP-Harry-Phillips]

I have a 32" monitor and if I do not want the text to be microscopic the scale is set to 150%

This makes the window.devicePixelRatio a value of 1.5

I set the canvas height and width to specific values:

When I ask for the SVG data it divides the width and height by the ratio

This results in an image that is not the specified values:

To get the image created to be the values I want I have to multiply them by the ratio, this does not sit well on the page with the layout I have, the canvas area ends up larger than I want it the rest of the form.

Is there a way of differentiating between the display setting zoom and the browser zoom?