impress/app/assets/stylesheets/application/magic-magnifier.sass
Emi Matchu b2a23b3e7b Add magnification when editing pet appearance
I couldn't find a library for this functionality that didn't require
jQuery, and I don't want to be adding *more* jQuery requirements. So, I
decided to throw together my own!

The `<magic-magnifier>` component copies its contents into a "lens"
element, then uses basic JS to track mouse position, then uses CSS to
move the lens and its contents into a helpful position.

One thing I noticed here is that the zoom is a bit crunchy because
we're using PNG images, and it's hard to zoom in even further than we
already are. I might try switching this UI to use the SVG images by
default instead?
2024-12-07 11:39:37 -08:00

40 lines
1.6 KiB
Sass

magic-magnifier
position: relative
&:not(:hover)
magic-magnifier-lens
display: none
magic-magnifier-lens
width: var(--magic-magnifier-lens-width, 100px)
height: var(--magic-magnifier-lens-height, 100px)
overflow: hidden
border-radius: 100%
background: white
border: 2px solid black
box-shadow: 3px 3px 3px rgba(0, 0, 0, .5)
position: absolute
left: var(--magic-magnifier-x, 0px)
top: var(--magic-magnifier-y, 0px)
> *
// Translations are applied in the opposite of the order they're specified.
// So, here's what we're doing:
//
// 1. Translate the content left by --magic-magnifier-x and up by
// --magic-magnifier-y, to align the target location with the lens's
// top-right corner.
// 2. Zoom in by --magic-magnifier-scale.
// 3. Translate the content right by half of --magic-magnifier-lens-width,
// and down by half of --magic-magnifier-lens-height, to align the
// target location with the lens's center.
//
// Note that it *is* possible to specify transforms relative to the center,
// rather than the top-left cornerthis is in fact the default!but that
// gets confusing fast with scale in play. I think this is easier to reason
// about with the top-left corner in terms of math, and center it after the
// fact.
transform: translateX(calc(var(--magic-magnifier-lens-width, 100px) / 2)) translateY(calc(var(--magic-magnifier-lens-height, 100px) / 2)) scale(var(--magic-magnifier-scale, 2)) translateX(calc(-1 * var(--magic-magnifier-x, 0px))) translateY(calc(-1 * var(--magic-magnifier-y, 0px)))
transform-origin: left top