/** @module fontScale */
/**
* Scale an element's font size so that it doesn't overflow the viewport.
* Note that some css may be required for this to work,
* for example setting `display: flex;` on the parent element,
* and this function relies on the element being visible.
* If you want to keep your element invisible until font scaling finishes,
* use `opacity: 0;`
* @param {HTMLElement} element the element to be scaled
* @param {Number} maxHeight maximum font size (which is equivalent to pixel hight)
* @returns {Number} the resulting font size
*/
export function fontScale(element,maxHeight=innerHeight){
return new Promise(function(resolve){
function scaleup(){
let size=parseInt(getComputedStyle(element).fontSize)
let bounds=element.getBoundingClientRect()
if(bounds.right<innerWidth && size<maxHeight){
element.style.fontSize=size+1+'px'
setTimeout(scaleup)
}else{
setTimeout(scaledown)
}
}
function scaledown(){
let size=parseInt(getComputedStyle(element).fontSize)
let bounds=element.getBoundingClientRect()
if(bounds.right>innerWidth || size>maxHeight){
element.style.fontSize=size-1+'px'
setTimeout(scaledown)
}else{
resolve(size)
}
}
setTimeout(scaleup)
})
}
export default fontScale