49 lines
2.0 KiB
JavaScript
49 lines
2.0 KiB
JavaScript
class WdeScrollBar{
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/**
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* @param {HTMLElement} handler
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* @param {HTMLElement} content
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*/
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constructor(handler, content){
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let nonNativeScroll = false
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handler.style.height = (content.clientHeight /content.scrollHeight)* handler.parentElement.clientHeight + 'px'
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let max = handler.parentElement.clientHeight - handler.clientHeight
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let yPosInit = 0
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handler.addEventListener('mousedown', (event) => {
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nonNativeScroll = true
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yPosInit = event.clientY - Number(handler.style.top.replace('px','' ))
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document.addEventListener('mousemove', drag);
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document.addEventListener('mouseup', stop)
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})
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content.addEventListener('scroll', (event) =>{
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if (!this.nonNativeScroll){
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let handlerPathLength = handler.parentElement.clientHeight - handler.clientHeight //TODO recalculate only on resize event
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let coefficient = (content.scrollHeight - content.clientHeight) /handlerPathLength
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handler.style.top = content.scrollTop/coefficient + 'px'
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}
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})
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function drag() {
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// console.log(event.clientY - yPosInit, Number(handler.style.top.replace('px','' )))
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let pos = event.clientY - yPosInit
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let clampPos = Math.min(Math.max(pos, 0), max)
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handler.style.top = clampPos + "px";
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let handlerPathLength = handler.parentElement.clientHeight - handler.clientHeight //TODO recalculate only on resize event
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let coefficient = (content.scrollHeight - content.clientHeight) /handlerPathLength
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// console.log(clampPos, coefficient, content.clientHeight, clampPos* coefficient)
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content.scrollTop = clampPos* coefficient
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}
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function stop() {
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// console.log("stop")
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document.removeEventListener('mousemove', drag);
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document.removeEventListener('mouseup', stop)
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nonNativeScroll = false
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}
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}
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} |