refactor: skip scroll to index when virtualizer has no items #1971
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tomivirkki
commented
May 20, 2021
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| scrollToIndex(index) { | ||
| if (typeof index !== 'number' || isNaN(index) || !this.scrollTarget.offsetHeight) { | ||
| if (typeof index !== 'number' || isNaN(index) || this.size === 0 || !this.scrollTarget.offsetHeight) { |
tomivirkki
commented
May 20, 2021
Comment on lines
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| if (el.style.minHeight) { | ||
| el.style.minHeight = ''; | ||
| } |
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Performance improvement, only reset min-height if it has a value beforehand
tomivirkki
commented
May 20, 2021
Comment on lines
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| let fvi = this.firstVisibleIndex + this._vidxOffset; | ||
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| const fviOffsetBefore = this.__getIndexScrollOffset(fvi); | ||
| // Record the scroll position before changing the size | ||
| let fvi; // first visible index | ||
| let fviOffsetBefore; // scroll offset of the first visible index | ||
| if (size > 0) { | ||
| fvi = this.firstVisibleIndex + this._vidxOffset; | ||
| fviOffsetBefore = this.__getIndexScrollOffset(fvi); | ||
| } | ||
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| // Change the size | ||
| this.__size = size; | ||
| this._itemsChanged({ | ||
| path: 'items' | ||
| }); | ||
| flush(); | ||
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| fvi = Math.min(fvi, size - 1); | ||
| this.scrollToIndex(fvi); | ||
| // Try to restore the scroll position if the new size is larger than 0 | ||
| if (size > 0) { | ||
| fvi = Math.min(fvi, size - 1); | ||
| this.scrollToIndex(fvi); | ||
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| const fviOffsetAfter = this.__getIndexScrollOffset(fvi); | ||
| if (fviOffsetBefore !== undefined && fviOffsetAfter !== undefined) { | ||
| this._scrollTop += fviOffsetBefore - fviOffsetAfter; | ||
| const fviOffsetAfter = this.__getIndexScrollOffset(fvi); | ||
| if (fviOffsetBefore !== undefined && fviOffsetAfter !== undefined) { | ||
| this._scrollTop += fviOffsetBefore - fviOffsetAfter; | ||
| } |
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Reorganize and document the code better.
tomivirkki
commented
May 20, 2021
| this._itemsChanged({ | ||
| path: 'items' | ||
| }); | ||
| flush(); |
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The additional flush() is now required after not invoking super.scrollToIndex (which in turn flushed) when the size is 0 (the issue was caught by tests)
web-padawan
approved these changes
May 20, 2021
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Prevent scroll to index when the virtualizer has 0 size.
Reorganize and document code in the iron-list-adapter.