remove the "textbox grows the 'wrong' way" behavior, replace it with more

conditions to scroll to bottom
This commit is contained in:
Henry Jameson 2019-10-08 20:53:55 +03:00
parent 6511a744a2
commit 37b8490c01

View File

@ -301,9 +301,6 @@ const PostStatusForm = {
const bottomPadding = Number(bottomPaddingStr.substring(0, bottomPaddingStr.length - 2))
const vertPadding = topPadding + bottomPadding
const oldHeightStr = target.style.height || ''
const oldHeight = Number(oldHeightStr.substring(0, oldHeightStr.length - 2))
/* Explanation:
*
* https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollHeight
@ -340,12 +337,17 @@ const PostStatusForm = {
// to find offset relative to scrollable container (scroller)
const rootBottomBorder = rootRef.offsetHeight + findOffset(rootRef, scrollerRef).top
const textareaSizeChangeDelta = newHeight - oldHeight || 0
const isBottomObstructed = scrollerBottomBorder < rootBottomBorder
const isRootBiggerThanScroller = scrollerHeight < rootRef.offsetHeight
const rootChangeDelta = rootBottomBorder - scrollerBottomBorder
const totalDelta = textareaSizeChangeDelta +
(isBottomObstructed ? rootChangeDelta : 0)
// The intention is basically this;
// Keep bottom side always visible so that submit button is in view EXCEPT
// if root element bigger than scroller and caret isn't at the end, so that
// if you scroll up and edit middle of text you won't get scrolled back to bottom
const shouldScrollToBottom = isBottomObstructed &&
!(isRootBiggerThanScroller &&
this.$refs.textarea.selectionStart !== this.$refs.textarea.value.length)
const totalDelta = shouldScrollToBottom ? rootChangeDelta : 0
const targetScroll = currentScroll + totalDelta
if (scrollerRef === window) {