Изменения

"By «By default, the grid will display rows at 25px. You can change this for each row individually to give each row a different height."» * Use reasonable fixed minimum row height* Always render (screen/minHeight) last rows* Find maximum possible viewport start (in units of item number + % of item)* Measure average height of last rows* avgHeight = max(minHeight, lastRowAvgHeight)* targetHeight = avgHeight*rowCount + headerHeight* Set sizer to targetHeight* scrollPos = targetHeight > offsetHeight ? min(1, scrollTop / (targetHeight — offsetHeight)) : 0* First visible item will be Math.floor(scrollPos*maxPossibleViewportStart)* Additional scroll offset will be itemOffset = scrollPos*maxPossibleViewportStart-Math.floor(scrollPos*maxPossibleViewportStart)*firstVisibleItemHeight* First (top) placeholder height will be scrollTop-firstVisibleItemHeight+itemOffset* Second (middle) placeholder height will be avgHeight*nodeCount — sum(heights of all rendered rows) — (first placeholder height)