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construct/share/webapp/js/scroll.js
2018-09-13 21:17:08 -07:00

107 lines
2.5 KiB
JavaScript

/*
// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
*/
'use strict';
/**************************************
* Scrolling & Viewport utils
*
*/
mc.scroll = {};
mc.scroll.at = function(e)
{
return $(e).prop("scrollTop");
};
mc.scroll.at.top = function(e)
{
return mc.scroll.at(e) == 0;
};
mc.scroll.at.bottom = function(e)
{
let st = $(e).prop("scrollTop");
let sh = $(e).prop("scrollHeight");
let ch = $(e).prop("clientHeight");
return sh - ch <= st + 1;
};
mc.scroll.to = function(e, pos, speed = "slow")
{
return $(e).animate({ scrollTop: pos }, speed);
};
mc.scroll.to.top = function(e, speed = "slow")
{
return mc.scroll.to(e, 0, speed);
};
mc.scroll.to.bottom = function(e, speed = "slow")
{
return mc.scroll.to(e, $(e).prop("scrollHeight"), speed);
};
/**
* top: the percentage of area invisible above the viewport.
* view: the percentage of the area in the viewport.
* bottom: the percentage of the area invisible below the viewport.
*/
mc.scroll.pct = function(e)
{
let st = $(e).prop("scrollTop");
let sh = $(e).prop("scrollHeight");
let ch = $(e).prop("clientHeight");
return {
top: st / sh,
view: ch / sh,
bottom: (sh - (st + ch)) / sh,
}
};
/**
* Given a DOM element, this function tests if the user can see the element,
* (and for now it returns true only if the *whole* element is in the viewport).
* Originally intended to figure out which events in the Matrix room timeline have
* fallen into the scrollback and can be removed.
*/
function isElementInViewport(e)
{
if(typeof jQuery === "function" && e instanceof jQuery)
e = e[0];
let rect = e.getBoundingClientRect();
return (
rect.top >= 0 &&
rect.left >= 0 &&
rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
rect.right <= (window.innerWidth || document.documentElement.clientWidth)
);
}
mc.get_rect = function(e)
{
if(typeof jQuery === "function" && e instanceof jQuery)
e = e[0];
if(e === undefined)
return undefined;
let rect = e.getBoundingClientRect();
return {
top: rect.top,
right: rect.right,
bottom: rect.bottom,
left: rect.left,
};
};