40 lines
2.4 KiB
JavaScript
40 lines
2.4 KiB
JavaScript
import ScalingCellSizeAndPositionManager from './ScalingCellSizeAndPositionManager.js';
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/**
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* Helper function that determines when to update scroll offsets to ensure that a scroll-to-index remains visible.
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* This function also ensures that the scroll ofset isn't past the last column/row of cells.
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*/
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export default function updateScrollIndexHelper(_ref) {
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var cellSize = _ref.cellSize,
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cellSizeAndPositionManager = _ref.cellSizeAndPositionManager,
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previousCellsCount = _ref.previousCellsCount,
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previousCellSize = _ref.previousCellSize,
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previousScrollToAlignment = _ref.previousScrollToAlignment,
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previousScrollToIndex = _ref.previousScrollToIndex,
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previousSize = _ref.previousSize,
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scrollOffset = _ref.scrollOffset,
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scrollToAlignment = _ref.scrollToAlignment,
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scrollToIndex = _ref.scrollToIndex,
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size = _ref.size,
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sizeJustIncreasedFromZero = _ref.sizeJustIncreasedFromZero,
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updateScrollIndexCallback = _ref.updateScrollIndexCallback;
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var cellCount = cellSizeAndPositionManager.getCellCount();
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var hasScrollToIndex = scrollToIndex >= 0 && scrollToIndex < cellCount;
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var sizeHasChanged = size !== previousSize || sizeJustIncreasedFromZero || !previousCellSize || typeof cellSize === 'number' && cellSize !== previousCellSize; // If we have a new scroll target OR if height/row-height has changed,
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// We should ensure that the scroll target is visible.
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if (hasScrollToIndex && (sizeHasChanged || scrollToAlignment !== previousScrollToAlignment || scrollToIndex !== previousScrollToIndex)) {
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updateScrollIndexCallback(scrollToIndex); // If we don't have a selected item but list size or number of children have decreased,
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// Make sure we aren't scrolled too far past the current content.
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} else if (!hasScrollToIndex && cellCount > 0 && (size < previousSize || cellCount < previousCellsCount)) {
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// We need to ensure that the current scroll offset is still within the collection's range.
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// To do this, we don't need to measure everything; CellMeasurer would perform poorly.
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// Just check to make sure we're still okay.
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// Only adjust the scroll position if we've scrolled below the last set of rows.
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if (scrollOffset > cellSizeAndPositionManager.getTotalSize() - size) {
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updateScrollIndexCallback(cellCount - 1);
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}
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}
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}
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import { bpfrpt_proptype_Alignment } from "../types";
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import { bpfrpt_proptype_CellSize } from "../types"; |